COMMONWEALTH OF AUSTRALIA

Department of Health

SERVICE PUBLICATION No. 28

Report on a Campaign against Diphtheria

at Bendigo, Victoria,


1923—1924


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(By


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KEITH R. MOORE, M.B., B.S. (Melb.),

' Medical Officer, Division of Laboratories, Commonwealth Department of Health.

UNDER THE AUTHORITY OF THE MINISTER FOR HEALTH

1925

By Authority:

H. J. Green, Government Printer, Melbourne.

H


COMMONWEALTH OF AUSTRALIA

Department of Health

SERVICE PUBLICATION No. 28

Report on a Campaign against Diphtheria

at Bendigo, Victoria,

1923—1924

fBy

KEITH R. MOORE, M.B., B.S. (Mdb.),

Medical Officer, Division of Laboratories,

Commonwealth Department of Health.

UNDER THE AUTHORITY OF THE MINISTER FOR HEALTH

1925

By Authority :

H. J. Green, Government Printer, Melbourne.

PREFACE.

Much has been written in other countries on various aspects of the immunity or susceptibility of the individual to diphtheria; and many claims have been made as to the value of immunization against diphtheria by the use of toxin-antitoxin mixture. No attempt has been previously made on any large scale to test the value of these measures under Australian conditions until I)r. Moore undertook the campaign at Bendigo, the results of which are herein recorded.

J. H. L. CUMPSTON, M.D., D.P.H.,

Director-General of Health.

25th June, 1925.

TABLE OF CONTENTS.

T.—Introduction—

Preliminary arrangements and organization for the campaign

II. —Swabbing Campaign, 1923—

Procedure and Results

Method of swabbing    .,    ..    ..    ..    ..

Examination of swabs    ..    ..    . .    ..    ..

Method of examination    ..    ..    ..    ..    ..

Isolation of carriers    ..    ..    ..    ..    ..

Number of swabs examined    ..    ..    ..    ..

Age and sex incidence of carriers    ..    ..    ..    ..

Period of carrier condition    ..    . .    ..    ..

Location of bacilli    ..    ..    ..    ..    ..

Distribution of carriers by schools    ..    ..    .    .

Relation of floor space to number of carriers    ..    ..

Influence of proximity in school    ..    ..    ..    ..

Throat conditions in carriers ..    .    .    .    .    ..

Review of work and results obtained    .    .    ..    ..

Virulence Tests

Method of test    ..    ..    ..    ..    ..

Preparation of suspension    . .    ..    ..    ..

Preparation of animals    ..    ..    ..    ..    ..

Technique of test    ..    ..    ..    ..    ..

Reading of results    ..    ..    ..    ..    ..

Masked reactions    ..    ..    ..    ..    ..

Description of lesions    ..    ..    ..    ..    ..

Modified methods adopted    ..    ..    ..    ..

Results of tests    ..    ..    ..    ..    ..

Age incidence    ..    ..    ..    ..    ..

Conclusions    ..    . .    ..    ..    ..

III. —The Schick Test—

Development of the test    ..    ..    ..    ..    ..

Natural immunity    ..    ..    . .    ..    ..

Publicity methods    ..    ..    ..    ..    ..

Preparation of the toxin    ..    ..    ..    ..    ..

Importance of fresh dilution    ..    ..    ..    ..

Technique of test    ..    ..    ..    . •    ..

Reading results    ..    ..    ..    ..    ..

Nature of reactions    ..    ..    ..    . .    . •

Pseudo-reactions    ..    .    .    ..    ..    . .

Statistics of tests performed    ..    ..    ..    ..

Age incidence    ..    ..    ..    ..    ..    ..

Sex variation    ..    ..    ..    ..    ..    . •

Influence of consanguinity    ..    ..    ..    • •

Previous history of diphtheria    ..    . .    ..    ..

Reactions of carriers    ..    ..    ..    ..    ..

Pseudo-reactions    ..    ..    ..    ..    ..

Age and sex incidence    ..    ..    ..    ..    ..

Sex incidence    ..    ..    ..    ..    ..    . •

A doubtful case of diphtheria in a recorded Schick negative reactor

PACK

I V.—A( TI V K IMM l' NIZATION—

Development of methods    ..    ..    ..    ..    ..    45

Procedure adopted    ..    ..    ..    ..    . .    .    .    47

Methods    ..    ..    ..    ..    ..    ..    ..    47

Reactions    ..    ..    ..    ..    ..    ..    .    47

Testing the effect of immunizing injections ..    ..    . .    ..    49

Age incidence of reactions after injections    ..    ..    ..    ..    52

V.—Review of the Campaign in    1923    ..    ..    ..    ..    ..    54

YJ.—Schick Test and Active Immu nization, 1924—

Procedure and methods ..    ..    ..    ..    ..    .    .    56

Table of results    ..    ..    ..    ..    ..    ..    57

Statistics    ..    ..    ..    ..    ..    ..    . .    57

Age and sex incidence    . .    ..    ..    .    . .    .    .    58

Previous history of diphtheria    ..    ..    ..    . .    .    .    58

Pseudo-reactions    ..    ..    ..    ..    ..    .    .    59

Age incidence    ..    ..    ..    ..    ..    ..    . .    59

Active immunization    ..    ..    ..    ..    . .    ..    59

Reactions    ..    ..    ..    ..    . .    . .    .    59

Testing of immunity    ..    ..    ..    ..    . .    ..    59

Age incidence of reactions after injections    ..    ..    . .    . .    60

Summary    ..    ..    ..    ..    .    .    . .    .    61

Vlf.—Review of the Campaign, 1923-1924    ..    ..    ..    ..    62

REPORT ON CAMPAIGN AGAINST DlPTHTHERIA, BENDIGO,
VICTORIA, 1923 1524.

I.—INTRODUCTION.

Preliminary Arrangements and Organization for the Campaign.

In December. 1922. I was requested to attend a meeting in the Bendigo Town Hall, convened by Dr. J. Mcl. Eadie, Medical Officer of Health for Bendigo, and consisting of the Health Officers of Eaglehawk and the Shires of Marong, Strathfieldsaye, and Elmore (Huntley Shire), as well as the newly-appointed State Health Officer for the District, Dr. P. Rowan, the (then) Medical Superintendent of the Bendigo Hospital, Dr. M. Jacobs, and the Health Inspector of Bendigo, Mr. Paynter.

The purpose of this meeting was to consider the advisability of conducting a diphtheria swabbing campaign among the school-children early in 1923, in order to anticipate the diphtheria season. This had been done in 1922 with the help of Dr. Featonby, of the State Health Commission, and the low incidence of diphtheria since then was considered sufficiently encouraging to warrant a similar campaign in 1923.

At the meeting it was decided to recommend to the various councils that a campaign be conducted on similar lines to the one already mentioned, and that the Commonwealth Health Laboratory, Bendigo, be asked to undertake the examination of the swabs.

On learning this I communicated with the Director-General of Health and, in return, received instructions to undertake the following programme of work in relation to the campaign :—

1.    Culturing and examination of swabs ;

2.    Virulence testing and isolation of positive strains ; and

3.    Trial of the Schick test and active immunization process.

At a conference of representatives from the various councils and health officers of the district, presided over by the Mayor of Bendigo, Cr. M. G. G indice, and held in the Town Hall, Bendigo, on 9th February, 1923, this information was communicated, and it was decided that swabbing should commence on 14th February in Bendigo.

The staff of the Health Laboratory, consisting of the late Technical Assistant B. G. Walker and myself, was augmented by temporary services of Dr. R. E. Butchart and Technical Assistant Barrett, from the Commonwealth Serum Laboratories, for the purpose of swab examination and assisting in the Schick tests, and of Technical Assistant D. A. Grant, also of Commonwealth Serum Laboratories, who was responsible for performing the virulence tests and isolating the pure strains.

The various health officers of the municipalities were responsible for the taking of the swabs and for forwarding them to the Laboratory for examination, and also for the isolation and reswabbing of carriers.

Ii.—SWABBING CAMPAIGN, 1923.

Procedure and Results.

The schools were worked systematically, and the children were swabbed at the rate of about 200 per diem, (’are was taken to round up all absentees and newcomers.

Method of Swabbing.

Nose and throat swabs were taken from every child and teacher ; but it was not considered necessary, in the first instance, to inoculate two separate tubes from nose and throat swabs in each case, as that would not. only increase the amount of material used, but also would waste a considerable amount of time in preparation and microscopic examination.

In inoculating, the tube was held in the left hand, the nasal swab inoculated in a streak along the outer edge of the culture surface, and the oral swab along the inner area, that is, towards the body. Inspissated serum was used as the culture medium, and was supplied from the Commonwealth Serum Laboratories.

The tubes were inoculated direct from the swabs at the schools, and were numbered serially. Careful records were kept, showing school, name, age, and sex.

The result of each day's swabbing was delivered to the Laboratory bv the health officer or inspector during the afternoon.

The tubes were then incubated at 37° C. overnight.

Examination of Swabs.

in actual working it was found that incubation overnight formed a profuse growth all over the surface of the medium in most cases ; accordingly, after the first day or two, the separate examination of oral and nasal cultures of the children was given up and one smear made from the whole surface of the tube for examination.

J he subsequent nose and throat swabs of all classed as carriers at the first examination were inoculated in separate tubes throughout, and separate smears made and examined.

*

Method of Examination.

The tubes were taken from the incubator the following morning, after about eighteen hours’ incubation, and smears were made from the cultures. The smears were stained for 2-5 minutes with Loeffler's methylene blue and examined under the 1—12 oil-immersion lens. These cultures in almost all instances revealed a confused mass of germs of various kinds. In a few instances almost pure cultures of diphtheria bacilli were found. Hoffmann's pseudo-diphtheria bacilli were especially numerous. All cases in which bacilli morphologically resembling B. diphtheria? were found, were notified as carriers.

Isolation of Carriers.

The carriers were re-swabbed at intervals of a week or less, and were kept away from their schools until two consecutive swabs were found to be free from B. dephtherue, or until the strain was proved to be avirulent. Printed instructions were issued by the municipality to each family in which a carrier existed, dhese instructions contained advice concerning general hygienic matters, as well as recommendations concerning the douching of the nose and gargling.

Y%

As the number of carriers increased from week to week, the total number of microscopic examinations averaged 300 per diem.

in cases where the second swabs were found to contain bacilli morphologically resembling B. diphtheriap, virulence tests were performed, and, if the strain were proved to be avirulent, the municipal authorities were notified and the child released from isolation.

When a typical virulent strain was noted it was isolated, if possible, and forwarded to Commonwealth Serum Laboratories.

Number of Swabs Examined, dec.

The total number of individuals swabbed was 7,174. This number represents the children and teachers of 58 schools in Bendigo, Eaglehawk, and the shires of Marong, Strathfieldsaye, and Elmore.

The actual number of teachers is not ascertainable, as in certain schools the records did not specify the age or sex, or distinguish in any way between scholars and teachers. Among those that did, the aggregate of teachers was 103.

The average age of the children was 8 *9 years.

Of the total (including teachers) 3,322 were males and 3,342 females, and in 510 instances the sex was not ascertainable from the records.

The total number of carriers detected was 696, giving a percentage of 9 *69. The average age of carriers was 8*7 years.

Of 3,322 males 353, or 10*62 per cent., were found to be carriers ; while among 3,342 females only 280, or 8*38 per cent., were carriers.

In the case of 103 teachers 15 carriers, equivalent to 14*5 per cent., were detected.

Of 510 cases in which the sex was not ascertained 63 were found to be carriers, equal to 12*35 per cent. This somewhat high relative percentage is probably accounted for by the fact that the number includes the remainder of the teachers.

The higher percentage of carriers among boys than among girls is difficult to explain satisfactorily.

The age and sex incidence table shows that the difference between the sexes becomes evident from the eleventh year onwards, the percentages of girlcarriers declining much more sharply than that of the boys from that time. This fact would seem to indicate that girls are more diligent in matters of hygiene, especially nasal and oral hygiene, than boys, and at an earlier age.

The high figure for teachers is noteworthy, particularly in view of the fact that the percentage curve of the children comes to zero at sixteen years. It would appear that the constant close contact with children of all ages renders teachers markedly liable to become carriers.

pr *

Sex.

Years.

Not

Stated.

rot.ii*.

Sex

Not

Stated.

Total.

3.

4.

5.

a.

7.

8.

9.

10.

n.

12.

13.

14.

15.

16.

17.

18.

19.

Number of swabs

/ M.

26

150

217

281

305

299

290

272

283

245

105

56

24

2

767

3,322

IF.

1

19

139

232

267

269

248

297

273

252

209

116

58

29

8

3

1

922

3,342

• •

Total

• •

1

45

289

449

548

574

547

587

545

535

454

220

114

53

10

3

1

1,689

6,664

510

7,174

Number of car-

f M.

15

19

24

34

31

20

36

23

18

5

2

126

353

riers

1 F.

• •

10

22

23

26

18

27

27

17

7

2

• •

• •

• •

101

280

• •

* •

Total

• •

• •

25

41

47

60

49

47

63

40

25

7

2

• •

• •

227

633

63

696

Percentage of

f M.

10*0

8*70

8*55

11*1

10*3

6*89

13*6

8*12

7*34

4*76

3*57

10*62

carriers

1 F.

• •

• •

7*1

9*48

8*61

9*7

7*2

9*09

9*9

6*74

3*34

1 *74

• •

• •

• •

• •

• •

8*38

• •

Total

• ♦

• •

• •

8*65

9*11

8-58

10*4

8*9

8*00

11 *5

7*47

5*50

3*18

1 *75

• •

• •

• •

9*49

12 35

9*69

A graph (Graph I.) has been plotted, showing the percentages of carriers— male, female, and total—against years of age.

Graph I. Age- and Sex - Incidence of Carriers.


Ages of Carriers. -* Year


A study of this shows us that the carrier-percentage remains fairly constantly at 8-10 per cent, for each year up to ten, and for both sexes. At the

age of eleven the boys’ curve shows a sharp peak to nearly 14 per cent., while that of the girls remains below 10 per cent. From that age onwards the percentages decrease, till at fifteen years only 3*5 per cent, of boys and no girls were found to be carriers.

The girls' curve is lower than that of the boys throughout this descent, as was mentioned in previous discussion. As the high percentage of male carriers at eleven years is preceded by an exceptionally low figure at ten years, it is not thought to be of any special significance.

Period of Carrier Condition.

Of the 696 carriers—

292 showed 1 positive swab only,

151

2

>>

swabs,

70

5 i

3

5 >

40

J >

4

? J

5 »

11

>5

5

CO

Î >

6

J J

,,

3

> J

7

>>

1

> »

CO

J »

55

while in 120 cases the incomplete records rendered it impossible to estimate the number of positive swabs.

The re-swabbing of carriers was conducted approximately on a weekly basis, and carriers were released after returning two consecutive negative swabs, or in the event of the strain of bacilli being proved avirulent. Hence it is seen that the great majority were released within a period of three or four weeks after being isolated.

Copeland, in the Report on Diphtheria, published by the Ministry of Health (Report No. 10), mentions the instance of nine carriers detected from 427 children at the Down end schools near Bristol at the end of March, 1921. He states that the carrier condition among these children had cleared up by the 25th April, a period of about four weeks.

Three American investigators—Guthrie, Golien, and Moss (Bull. Johns Hopkins Hosp., Baltimore, 1920, No. XXXI., pp. 388-403)—swabbed each of 50 carriers once a fortnight for three months. At the end of that period six were still found to be carriers.

Tt will be noted that, in the series quoted above, only one carrier from 576 showed eight positive swabs, and three only showed seven. Thus the maximum period in this series did not exceed three months.

Ijocation of Bacilli.

The relative frequency of detection of diphtheria bacilli in the* nose and throat swabs of carriers is shown in the following table :—

Table 2.—Showing Location of Bacilli.

Aiie.

Location.

Sex.

5.

6.

7•

8.

0.

10.

11.

12.

18.

14.

15.

Not Stat evi.

Total*.

M.

3

7

7

9

11

4

7

2

2

8

CO

Nose

f

•\

F.

3

10

6

2

4

0

4

3

• •

1

• •

6

45

Total

• .

• •

6

17

13

11

15

10

11

5

2

1

• •

14

105

I

M.

l

1

9

1

4

1

6

2

2

1

9

23

Throat

• i

*-•

2

4

2

5

2

3

4

3

2

• •

1

28

Total

• •

• •

3

5

4

0

4

3

9

6

5

3

• •

3

51

1

M.

6

3

4

8

7

5

0

2

1

l

43

Both

"\

F.

1

1

4

2

1

5

3

5

3

1

• •

2

28

Total

• •

1

7

7

0

9

12

8

11

5

2

3

71

f

M.

4

14

12

14

23

12

18

10

0

2

11

120

J. UuHlS

" \

F.

6

15

12

9

5

13

10

12

6

4

• •

9

101

Total

• •

-

10

29

24

23

28

25

28

22

12

6

• •

20

227

This table is compiled from a series of 227 cases, each of whom returned at least two positive swabs, as it was found impracticable to discriminate in all carriers, owing to the pressure of work.

The figures indicate that 46 per cent, of carriers showed bacilli only in the nose after one week of isolation, accompanied by daily gargling and douching, and following out the general hygienic instructions issued by the Municipal Health Officers.

Of the remainder, 22 per cent, showed bacilli in the throat only, while in 32-33 per cent, of cases, bacilli wTere found in the swabs from both nose and throat.

These figures appear to show that gargling was more thoroughly carried out than nasal douching by carriers, or, alternatively, that it is very much more difficult to rid the nose of bacilli than the throat.

They also point out very clearly the strong advisability of taking both nose and throat swabs in diphtheria work. Unless both are taken, not only will a great number of carriers be overlooked, some of whom will prove to harbour virulent bacilli, but also a large number will be released from isolation at a period at which they are still infective.

The following table shows the percentage of carriers in the various districts and in

the schools of each district also:


Table 3.—Distribution of Carriers by Districts and Schools.

No.

School.

Average

Age.

No. of

-

No. of

Averagc

Percent-

Number of Positive

Swa I*.

Teachers

Viru

lent

Tests.

Posi-

N ega -

Percen

tage

Posit i Vr.

Swabs.

Carriers.

A tie.

a'.*e.

1.

2

8.

4.

5.

ti.

i .

8.

( ,'arriers.

l ivo.

tive

Bendigo School*.

1

15

8

46 * 6

1

Gravel Hill S.S.

7*0

536

48

8*2

9-0

21

11

8

4

3

. •

7

2

Central School ..

9*4

G87

88

9*7

12*7

43

20

13

7

3

2

. .

27

15

12

55 ’ 5

3

Quarry Hill S.S.

8-0

290

24

7*9

7 *5

12

3

5

4

..

..

2

10

5

5

50*0

4

Golden Square S.S.

8-0

476

47

8*8

9*8

19

13

7

6

2

3

18

6

12

33 *3

5

Violet-street S.S.

8*4

53G

121

8*1

22*2

49

40

13

13

1

3

1

1

3

39

17

22

-4 1 *0

6

Rae’s Hill S.S. ..

11*9

149

15

11*7

10’0

10

2

3

. .

1

..

l

7

Specimen Hill S.S.

8*2

96

21

8*8

21*8

14

5

..

1

1

1

4

1

3

25*0

8

Long Gully S.S.

8-4

168

7

8*6

4-1

6

1

..

9

Bendigo North S.S.

8*4

240

14

8*8

5*8

9

3

2

..

10

Bendigo East S.S.

8*2

87

5

8*7

5*7

3

1

..

1

11

Miss Jackson’s School

N.S.

3

v .

. •

• .

• .

..

..

12

St. Killian’s School

8*1

348

26

8*6

7 *5

10

5

6

2

1

1

1

13

Marist Brothers’ School ..

11*3

242

17

10*8

7*0

9

5

2

1

14

St. Joseph’s School

8-0

148

3

7-3

2 * 1

3

..

..

15

Girton C.E.G.G.S.

11 *7

63

4

7 *5

6*4

4

10

Convent of Mercy ..

10*2

174

10

12*0

5*7

5

5

..

17

Bendigo High School

14-2

283

15

14*4

5*3

8

5

2

18

Technical School

14-0

211

22

12*5

10-4

16

4

2

19

Domestic Arts ..

12*6

175

12

12-3

6*8

5

6

1

20

Not stated, taken at Town

Hall..

N.S.

31

9

N.S.

» ,

2

5

l

1

4

4

21

White Hills S.S.

8*1

101

8

8*3

8*0

5

3

..

• •

22

White Hills R.C. School ..

8 *4

43

2

10*5

4*6

1

1

Totals

5,087

518

10*1

254

137

66

40

10

7

3

1

9

118

51

67

13-2

School.

\ verace

No. of

No. of

A vc rage Ago.

Percen-

Number of Positive Swabs.

Teachers

Viru

lent

Tests.

Posi-

Neun-

Perce n-taue

Posit ire.

No.

Age.

Swabs.

Carriers.

tage.

1.

O

3.

4.

5.

0.

7.

8.

Carriers.

tiVQ.

tive

Eaglehawk Schools.

1

1

1

23

Eaglehawk Central School

N.S.

487

47

N.S.

9*6

3

• •

24

St. Liborius’ School

ty

100

12

yy

12*0

• •

1

• •

• •

25

California Gullv

7 *7

120

5

8*6

4*1

• •

• •

• •

• •

• •

26

Eaglehawk North S.S.

8*4

76

11

7*4

14*5

Not available.

J

• •

• •

• •

• •

27

Absentees, &c., school not

stated

N.S.

49

19

N.S.

• •

• •

♦ •

* *

* 4

* *

Totals

..

832

94

• •

11*3

>

-1-

3

2

• *

2

• •

Marong Shire Schools.

7

1

1

28

Kangaroo Flat S.S.

N.S.

145

9

N.S.

6*2

1

• •

• •

29

St. Monica’s R.C. School . .

yy

44

3

yy

7*0

2

• •

• •

30

St. Sebastian S.S.

9*8

53

2

4*5

4*0

2

• •

31

Diamond Hill S.S.

10-8

14

• .

..

..

• •

32

Big Hill S.S. ..

N.S.

39

3

N.S.

7*6

3

• •

• •

• •

• ♦

• •

Totals

..

295

17

• •

5*7

14

1

1

• •

1

• •

• •

33

Strathfieldsaye Schools. Spring Gully S.S.

9*4

51

8*6

9-0

9*9

3

1

1

D

3

1

34

Kennington S.S.

7 *5

54

4

7*4

• •

1

1

• •

35

Sedgewick S.S. ..

10-2

18

2

..

11*1

• •

2

• •

36

Mandurang S.S.

9*3

39

2

10 ’5

5*1

2

• *

• •

37

Emu Creek S.S.

9*3

22

..

..

..

• •

• •

• •

38

39

Eppalock S.S. Strathfieldsaye S.S.

8*2 8'6

25

28

3

li *6

10*7

2

1

..

40

Junortoun S.S. ..

8*6

26

1

6.0

3 ’ 7

. •

1

1

41

Axedale S.S.

8*6

50

2

..

4*0

2

• •

42

Longlea S.S.

9*4

26

• •

• •

• •

• •

...

• •

*•

• •

• •

* *

»

___i;__

Totals

339

19

• •

5*6

12

5

L

• •

• •

1

1

!

1 « «

3

l

• •

••

No.

School.

Average

Age.

No. of

No. of

A verage Age.

He i cem-

Number ot Positive

Swai

is.

Teachers

Viru

lent

Tests.

l*osi-

Neva-

Percen

tage

Posit i ve.

Swabs.

Carriers.

tage.

1.

o

O

V*»

4.

5,

c.

1,

s.

Carriers.

t Ivc.

tive

Elmore School

43

Elmore S.S.

N.S.

127

9

N.S.

7*1

0

3

• •

44

Elmore K.C. School

72

8

99

11 -l

0

1

1

45

May Reef S.S. ..

99

14

♦ ♦

99

. .

..

. .

46

Kamarooka E.S.S.

99

18

2

9 9

11-1

2

• •

47

Eosterville S.S. ..

18

99

..

• *

• .

48

Kamarooka S.S.

99

24

1

99

4*2

• .

1

49

Drumarton S.S...

99

10

2

99

12*5

2

• •

50

Avonmore S.S. ..

99

20

3

99

11*5

r

51

Barnedown S.S.

99

45

6

99

13*3

52

Ellesmere S.S. • •

99

20

3

99

15*0

Not av

aila ble.

4

53

Huntly S.S.

99

59

0

99

10-1

54

Huntly North S.S.

99

14

2

99

14*3

j

l

55

Hunter S.S.

99

15

• •

99

..

•• !

• • i

••

• •

• •

.. | ..

50

57

Bagshot S.S. Diggora S.S.

99

99

28

20

4

2

99 9 9

14*3 7 *7

\

\

Not available.

{

58

Not stated

99

99

• •

99

Totals

• -

021

48

• •

7 *7

12

8

2

• •

• •

Grand totals (average)

8-9

7,174

090

8*7

9-09

292

151

70

40

11

8

3

1

15

120

51

09

42*5

This table shows the percentage of carriers found in the various districts, and in the schools in each district also.

In Bendigo the percentage of carriers among 5,087 children was 10*1. The percentage of carriers in single schools ranged as high as 22*2 in Violet-street State School, one of the largest of the schools swabbed. The lowest figure which can be accepted is that of St. Joseph’s School, with 2*1 per cent, carriers. The case of Miss Jackson's School, with only three pupils and no carriers, is not worth including.

In the Eaglehawk district 832 children gave 11 *3 per cent, carriers, a figuro comparable to that of Bendigo. In this borough the Eaglehawk North State School, with 76 pupils, showed the highest percentage of carriers, viz., 14*5 per cent., while California Gully State School, with 120 scholars and 4*1 per cent, carriers, gave the lowest.

Marong Shire, with 295 school children, showed only 5*7 per cent, carriers. Very slight variations occurred between the schools, Big Hill State School, with 39 children and 7 6 per cent, carriers, giving the highest figure. The schools of this shire are still situated in thinly-populated areas.

The schools of the other two shires, Elmore and Strathfieldsaye, are, for the most part, very small, the majority having rolls of from 14 to 30 pupils. Consequently, it is useless to consider the individual percentages of carriers. Six schools out of the total of 25 in these two shires were free of carriers.

These figures show that in the more congested areas, Bendigo and Eaglehawk, from 10 per cent, to 11 per cent, of carriers were found ; while in the outlying rural districts 5 7 per cent, only were detected.

The geographical distribution of the schools in eacli district further evidences the influence of congestion on the carrier rate. With the exception of Specimen Hill State School (218 per cent.), which is situated in an open area, all schools approaching 10 per cent or over of carriers, and of whose pupils the average age is under ten years, are situated in the most congested parts. The case of Specimen Hill, with 21 '8 per cent, carriers, is partly explained by its proximity to Violet-street (22-2 per cent). It is probable that a number of its pupils come from the Violet-street district, which is thickly populated.

Tlae’s Hill State School, although situated very close to Violet-street, and being an adjunct to that school, shows only 10 per cent, of carriers. This is explained by the average age of the scholars, 11 *9 years, which is much higher than the average for most schools, and at which age, according to the Graph I., the incidence of carriers is already falling.

Among schools showing a relatively low percentage of carriers in the Bendigo district, two classes are to be identified. Firstly, those with a high age average, such as the High School (average age 14 *2 years, 5 *3 per cent, carriers), Domestic Art Centre (average age 12*6 years, 6*8 per cent, carriers), and Girton C.E.G.G. School (11-7 years, 6*4 per cent, carriers). Secondly, those situated in less congested areas, such as White Hills State School (8 per cent.), Bendigo North State School (5*8 per cent.), and Bendigo East (5*7 per cent.).

C.5745.—2

Relation of floor Space to Number of Carriers.

With a view to ascertaining the relationship, if any. which floor space per child bears to the percentage of carriers in any school, the floor areas of a few of the schools, representing high and low carrier percentages, were ascertained. The following table demonstrates the results :—

Table 4.—Relation of Floor Space to Percentage of Carriers.

Name of School.

Number

of

Pupils.

Floor Area in Square Feet, per Child.

Percentages

of

Co rriers.

Violet-street S.S. ., .. ..

536

13*4

22*2

Eaglehawk North S.S. .. .. Rae’s Hill S.S. .. .. ..

76

27*0

14*5

149

19*0

10*0

(av. age 11*9)

Gravel Hill S.S. .. .. ..

536

13*2

9*0

Long Gully S.S. .. .. ..

16S

18*0

4*1

Bendigo East S.S. .. .. ..

87

17*2

5*7

From this table it does not appear that the influence exercised by floor area is very marked, although Violet-street possesses a small floor area per pupil compared with that of most other schools, and the percentage of carriers is relatively very high. At the same time, the liberal allowance of 27 square feet per child at Eaglehawk North is associated with the high carrier percentage of 14*5, and at Gravel Hill the low floor area of 13*2 square feet accompanies a relatively low carrier percentage of nine. At Pae’s Hill School, where 19 square feet are allotted per child, 10 per cent, of carriers were found among children whose average age was 11*9 years. This, like Eaglehawk North, indicates a relatively high carrier rate with a liberal floor area pei child.

Influence of Proximity in School.

It was remarked, during the examination of the swabs, that several positives were frequently observed in close succession. Thirty or 40 successive swabs might yield no carriers, and then, in the following dozen, perhaps six would be positive.

This leads one to inquire into the matter of the routine taking of the swabs. The children were swabbed, in the majority of instances, and especially in the larger schools, by classes. The tubes were numbered serially, and the names and numbers serially inscribed in the record book at the Laboratory. The tubes, after incubation, were arranged in the same serial fashion, and the smears were made and examined in numerical order. Thus it is evident that the carrier con- * dition existing in one child shows a decided tendency to be communicated to his or her school contacts, and that continued proximity in a closed room can cause the carrier condition to spread.

The tendency for several members of one family to become carriers was also noticed during examination, and it is regretted that an opportunity was not available to inquire into the home conditions of these carrier families. At the same time the fact presents additional evidence to support the previous argument.

Throat Conditions in Carriers.

An examination was made of the throats of carriers. This was not done at the time the carrier condition was detected, as arrangements were impracticable just then, but some three months later. Consequently the full series was not obtained. The examination was purely superficial, in order to ascertain the presence of gross pathological conditions, especially with regard to the tonsils.

In reports to the Minister of Education by Dr. Jane S. Greig, School Medical Officer of that Department, it is stated that about 12 per cent, to 15 per cent, of children in elementary schools are found to be suffering from enlarged tonsils and other throat and nose defects.

The percentage is said to be falling, and this fact is stated to be due to the number of children who undergo operation, as a result of recommendation by the medical officers of the Department.

Examination of a series of 214 children who had been carriers in 1923 in Bendigo revealed the fact that 48, or 22.4 per cent., were suffering from markedly enlarged tonsils ; while in 101 cases, representing 48.6 per cent., slight enlargement was noticed. Of the remainder, 33 children, or 15.4 per cent., showed minor lesions, such as engorgement of the fauces, enlarged uvula, and chronic pharyngitis. Only 29 children possessed throats that were classed as free from defects.

• In many cases in which the tonsils were very much enlarged there was observed pitting and, frequently, follicular spots of exuding pus, indicating the grossly diseased nature of the tonsils. These cases were usually associated with furred tongue and foul breath.

The percentage of carriers with throat defects is, thus, very high, compared with that normally found among school children, and this fact indicates clearly that a diseased throat forms a suitable nidus for the growth of Klebs-Loeiller bacillus and kindred organisms.

Review of the Swabbing Campaign and Results Obtained.

Residts Obtained.—In reviewing the figures obtained in the swabbing section of this campaign, the following facts are evident:—

1.    That the highest percentage of carriers among school children occurs

up to the age of eleven years, and about equally in both sexes up to that age.

2.    That, after the age of eleven years, the percentage of carriers at each

year of age declines sharply, till, at sixteen years, no carriers were detected in our series.

3.    That the percentage of female carriers is definitely less than that of

males, and that this decrease occurs after the age of ten years.

4.    That teachers are especially liable to become carriers, probably on

account of their close association with the younger children.

5.    That, in the great majority, the carrier condition clears up within four

weeks, but that it may exist for two or three months in certain instances.

6.    That the percentage of carriers in congested districts is nearly double

that in rural districts.

7.    That, while the carrier condition is very liable to be communicated

from one child to another by prolonged close contact during school hours, or in the home, the floor area allotted to each child in school does not govern this percentage, provided it is greater than the minimum allowance recognized by the Education Department.

8.    That the carrier condition is, in the majority of cases, associated with

pathological conditions of the throat and nose. In this connexion it is noteworthy that very few of the children examined were pronounced mouth-breathers. Only one or two instances were noted in the whole series.•

Apparently the factors named in paragraphs 6, 7, and 8, namely, congestion of district, floor area allowance per child in school, proximity of position in class, together with contact at home, and, finally, the state of health of the throat and nose, all exert their influence in determining the carrier percentage in any school or district.

Of these factors undoubtedly the most potent is the last named, and a vigorous effort, directed at the inducement of parents to having these defects remedied in their children, should be productive of surprisingly good results in the reduction of the diphtheria rate in the community. The low diphtheria rate which is the result of a campaign such as this, is at least partly due to the fact that the douching and gargling ordered for carriers ameliorates catarrhal conditions of the naso-pharynx, and consequently a certain percentage of the child population is more fitted to resist the disease.

Regarding the relation exercised by the floor area provided in any school per pupil, the results tabulated of the figures obtained are, as beforementioned, inconclusive. All the floor areas mentioned are well above the minimum allowance prescribed by the Education Department, which is 10 square feet per child in old schools, i.e., schools built prior to the enforcement of the regulations, and 12*5 square feet per child in the more modern schools.

Consequently, it. is not to be expected that the floor area allowance under these conditions could be shown to influence the carrier rate. Therefore, the question of the influence of proximity rests on the factors of position in the class-room and contact in the home.

The class-room factor has been shown to be of importance in this connexion, and the family incidence of carriers proves that home contact is in some measure responsible for the spreading of the condition. Unfortunately, time has not permitted one to inquire into the home conditions of the carriers.

Influence on the Diphtheria Incidence.

Below are appended the figures of incidence of diphtheria in Bendigo for each month from January, 1919, to date. Only notifications of clinical diphtheria have been taken into account:—

Table 5.—Monthly Notifications of Cases of Diphtheria in Bendigo, 1919 to August, 1923.

Year.

Jan.

Feb.

Mar.

April.

May.

June.

July.

Aim.

Sept.

Oct.

Nov.

Dec.

Total

1919 ..

16

6

5

9

5

9

5

9

12

5

6

5

92

1920 ..

7

18

71

58

48

29

37

16

22

21

6

17

350

1921 ..

8

10

48

67

133

77

39

25

19

12

11

20

469

1922 ..

16

24

53

43

18

17

13

6

5

1

1

1

198

1923 ..

3

4

10

10

16

13

10

NJ

It will be noted that the years 1920 and 1921 were marked by epidemics of the disease, and that, after the commencement of last year's swabbing campaign in March, 1922, the incidence fell considerably, and has remained low ever since.

It was thought that the dryness of the season might have borne some relation to the incidence of diphtheria, consequently the monthly rainfall from January, 1919, was ascertained.

Table 6.—Monthly Rainfall at Bendigo, 1919 to August, 1923.

Year.

Jan.

Feb.

Mar.

April.

May.

June.

.lu!y.

Aug.

Sept.

Oct.

Nov.

Dec.

Total.

1919 (pts.)

7

257

180

68

236

136

58

104

146

81

50

237

1,560

1920 „

27

5

39

62

178

282

212

491

505

393

275

44

2,513

1921 „

308

75

239

20

289

370

165

215

463

144

206

85

2,149

1922 „

16

118

13

87

222

150

102

145

195

242

14

92

1,396

1923 „

25

1

9

o

L*

278

474

525

148

• •

• *

• •

• •

• •

Graph Xo. II. shows the rainfall and diphtheria incidence plotted together.

Graph II. Monthly Diphtheria .Incidence and Monthly Rainfall. 1919-23.


euoq^dig jo JsquinN

An examination of this graph makes it clear that a high diphtheria incidence neither coincides with nor necessarily follows a wet season.

In 1919 the months of February, March, and May all produced over 2 inches of rain, and the diphtheria incidence was low throughout the year. Again, the high diphtheria rate in March, April, and May, 1920. followed a dry January and February, and coincided with a dry March and April. The exceedingly wet months of June to September of that year were marked by a progressive falling in the diphtheria rate.

Similarly, in 1921 the diphtheria epidemic preceded the wetter months of the year, and in 1922, likewise, the highest diphtheria incidence occurred during the dryer months.

Accordingly, it cannot be held that the low incidence of diphtheria since April, 1922, is due to the exceptionally dry weather experienced in the district.

Quarterly returns for corresponding years from Ballarat show that, while the diphtheria incidence in that city is usually much smaller than that in Bendigo, that for the present year is in excess of the Bendigo figure.

Table 7.—Quarterly Notifications of Diphtheria in Bendigo and Ballarat, 1919 to June, 1923.

Place.

1910.

1920.

1921.

1922.

19

23.

1st.

2nd.

3rd.

4th.

1st.

2nd.

3rd.

4th.

1st.

2nd.

3rd.

4th.

1st.

2nd.

3rd.

4th.

1st.

2nd.

Ben(11 no ..

27

23

20

10

00

135

75

44

00

277

83

43

93

78

24

3

17

33

28

Ballarat ..

13

7

25

18

40

100

72

52

09

174

41

23

31

40

23

11

23

Taking the first six months in each city for the last five years, the Bendigo notifications read as follows :—50, 231, 343, 171, and 50 ; while those of Ballarat read as follows 20, 206, 243, 77, and 51. These figures show that, while the number of cases in Ballarat is smaller for 1923 than in the two previous years, it is relatively considerably larger than the Bendigo quota.

From this one deduces that some other factor than the natural epidemic curve has affected the Bendigo district and reduced the diphtheria incidence, namely, in all probability, the swabbing campaign.

It has been stated that no proof exists that carriers, even of proved virulent bacilli, are capable of causing clinical diphtheria in contacts.    .

Granted that this is so, it is not to be denied that circumstantial evidence of the strongest nature exists to refute this statement.

Consequent on the inauguration of the swabbing campaign in Bendigo in March, 1922, the diphtheria incidence fell to a lower rate than had been experienced for years, and remained low throughout the rest of the year.

Further, the institution of this second campaign in February, 1923, has been marked by the cutting down of the number of cases reported during March, April, May, and June of this year to less than one-third of the average for the four preceding years.

It has already been shown by comparison with the Ballarat notifications that, while the number of clinical cases for this year is decreased in that city, the number in Bendigo shows proportionately a far greater decrease for the same time period.

It is assumed, therefore, that the isolation and treatment of carriers bears a definite relation to the incidence of clinical diphtheria.

In further support of this supposition is the fact that, during the past month of August, no cases of diphtheria were notified in Bendigo or Eaglehawk, and also that the diphtheria ward in the Bendigo Hospital has now been empty for nearly three weeks. At no other time in the history of the hospital has it remained empty for more than two hours.

Virulence Tests.

Method of Tests.

This part of the programme presented by far the greatest number of difficulties in execution, and it is regretted that it was not found possible to keep pace with the continuous stream of fresh carriers in this matter. At the outset one realized that it would not be practicable to attempt virulence tests on all strains classed as B. diphtherias, especially as the first tests were performed after isolation of a pure culture. Moreover, the identity of the bacilli, in many cases, was doubtful at the first swabbing, all suspicious bacilli were classed as B. diphtherias, and, in the interest of public safety, the hosts notified as carriers. At the second swabbing of carriers, where separate tubes were inoculated from nose and throat, not only was it easier to distinguish between morphological characteristics of bacilli, but also an opportunity was afforded of confirming the previous diagnosis, or otherwise.

Accordingly it was decided to test the virulence only of those cultures which were classed as positive at the second swabbing.

When it was found that this measure even did not enable 11s to keep pace with the swabbing, it was found necessary to alter the method of procedure, and to adopt one in which a preliminary isolation of a pure strain was not necessary.

The method adopted was, in essence, that of Force and Beattie, as outlined in the American Journal of Hygiene (Vol II., No. 5, Sept., 1922). These workers made use of the idea of intracutaneous inoculation with a suspension of bacilli made direct from throat or nose cultures, and without preliminary isolation of the diphtheria bacillus.

The method of intracutaneous testing was originally described by Neisser and modified by Zingher and Soletsky (Journal of Infectious Disesases, Vol. 17, No. 3, 1915), and is closely parallel to the Schick test on humans in technique and character of reaction.

Modifications have been introduced by various workers, including Eagleton and Baxter, of England, who advocated the giving of a following injection of 500 units diphtheria antitoxin to save the lives of the animals.

The method of Force and Beattie introduces still further changes, includili the most important one of omitting the isolation of B. diphtherice and inoculatili with suspension made direct from throat cultures. Their method, in detail, is as follows :—

to to


After 17 to 21 hours incubation smears are made from the cultures and examined. Cultures showing positive results are kept at room temperature until the afternoon, when the tests are made.

Preparation of Suspension.—After preparing a check smear from the culture, 2*5 cc. of normal saline are added to the tube and the growth scraped oft' the surface of the medium with a platinum wire. The suspension is then decanted into a sterile test tube and compared with a standard suspension for turbidity. Normal saline is added until the turbidity is the same as the standard. The suspension is then transferred to a sterile Petri dish to enable easy withdrawal by a syringe.

Preparation of Animals.—The long hairs are plucked from the sides of two white guinea-pigs and the residual short hairs shaved.

One animal, used as a control, is given 500 units diphtheria antitoxin a few moments before the test is performed.

i his modification of the method advised by Eagleton and Baxter was made after some experiments by Schick and Novotny, which showed that it was quite unnecessary to inoculate the control animals on the preceding day. rhe advantage gained is the saving of the inoculation of unnecessary animals, as it is impossible to anticipate the number of positive cultures which will require testing.

Technique of Test.—Enough of the above mentioned suspension is inoculated into each animal intracutaneously to produce a bleb, approximately 10 mm. in diameter—this amount varies between 0* 15—0* 2 cc.

Two to four different suspensions may be tested on each animal.

The inoculations arc made at least an inch apart, to avoid confluence of the reactions.

Readinq of Results.

The inoculated animals are observed daily for four or five days and measurements made of all lesions. Animals dying are examined for signs of the toxic action of B. diphthence, and, in the absence of these, cultures are made from the heart’s blood.

Masked Reactions. —Difficulty was experienced by Force and Beattie in reading results when field cultures,” or suspensions made direct from throat cultures, were used, owing 'to concurrent infections by other organisms than B. diphtherice obscuring the typical reaction. These reactions are described later. Once the difficulty of the masked reactions was overcome, the reading of results was easier.

Description of Lesions.—The typical lesion of a virulent diphtheria strain, when inoculated intracutaneously, lias been described by several writers, but it will be as well to detail it again here.

It may be paralleled in experiment by administering 0* 1 M.L.D. of diphtheria toxin intradermally to a guinea-pig.

Within 24 hours from the time of inoculation a slightly elevated reddened area, about 20 mm. in diameter, appears at the inoculation site, with some induration. The redness and induration reach their maximum within 48 hours, measuring 25 to 30 mm. in diameter, and during the second day, in the centre of the area appears a white patch, about 10—15 mm. in diameter. As this in turn increases in diameter, its centre becomes dark and purplish. During the third day the redness and induration decrease somewhat and the white area remains. During the third and fourth days the white area diminishes in size, and the purple centre becomes darker, with flakes of epithelium peeling away, showing necrosis. On the fourth or fifth day this necrotic area forms a brownish crust.

Injections of B. diphtheria? show the same target-like reaction as that just described, but in a milder form.

The control animals in each instance show nothing beyond a slight blush, which disappears in 24 hours, and the needle track.

When mixed cultures from throat swabs are used, the reaction proceeds in a similar manner, provided the animals are protected against infection by foreign organisms.

In our experience many reactions were found to be more or less obscured, in spite of the prophylactic measures instituted to protect them against foreign organisms, and, of course, the masking infection occurred in control animals as well as the normal.

This masking rendered it very difficult at first to read the typical reaction, and it was found that considerable experience was necessary to obtain accurate readings.

Modified Methods Adopted.

It was found necessary in our work to introduce further modifications of the original method in performing the tests, to combat with different circumstances which presented themselves, and also for the-purpose of time saving.

At first tests were done at the rate of two strains per animal; but this was later increased to four or more, enabling 20 to 25 strains to be tested per diem.

Experiment 1, conducted by Technical Asst. Grant, for the purpose of instituting a comparison between lesions caused by emulsions of known content.

Since 15 to 20 per cent, of emulsions inoculated appeared to give masked reactions, due to infection hy other organisms, and occurring in both control and normal animals, it was decided to mix suspensions of a pure K.L.B. strain and a typical non-positive emulsion, or rather, one that gave no typical reaction when tested.

This mixture was inoculated into the same side of a guinea-pig as the field-culture emulsion, enabling a comparison to be made more easily.

0* 2 c.c. of a suspension of a field-culture (A) was inoculated intracutaneously on the left side of a shaven animal anteriorly. To the same suspension was added 2 to 3 c.c. of a pure laboratory culture of B. diphtheria, and 0* 2 c.c. of the mixture (B) was inoculated posteriorly on the same side of the animal.

In 24 hours both inoculations had caused redness around the puncture, with a raised area -X) x 15 mm. in each instance. The centre of the raised area was whit'', with a purplish patch in its centre. These appearances were somewhat smaller in the case of suspension B than in A. The measurements of the white areas were approximately 8 x 6-5 mm. and of the purple centres 5 x 4—3 mm.

In 48 hours the redness and induration had decreased to 25 x 15 mm. in the case of A and 20 x 15 mm. in the case of B. On the other hand, the white area had increased in A to 10 x 6 and also slightly in B.

In 72 hours the redness had diminished still further around both inoculation sites and was only faint.

In A the white area had increased to 15 x 15 mm. and was raised up, while the purple centre measured 10x5 mm. and a scab had formed, which was folding and separating at the edges. In B the central area measured 15 x 15 mm. and was a flat scab, 7 x 4 mm. in extent, and surrounded by a white annulus.

In 96 hours the site of inoculation with A presented still some redness and induration, the whole area measuring 20 x 15 mm. The purple area, measuring 7x6 ram., was sunken throughout its extent to a depth of 2 mm., and the epithelium was peeling around the edges.

In B the redness and induration measured 15 x 15 mm., and closely resembled that of A in appearance. The central area measured 7x7 mm., with a brownish scab, peeling and sunken, and showing greyish epithelial flakes.

This experiment shows that the presence of a small proportion only of B. diphtheria* was not productive of a reaction easily distinguished from that of the ordinary “ field-culture,” containing organisms producing “ masking ” reactions.

Masked Reactions.—Masked reactions as described, occurring in both normal and control subjects from the very beginning of the tests, made clear the fact that definite measures were needed to prevent these infections by foreign organisms. Accordingly a second experiment was undertaken by Mr. Grant, as follows :—

Experiment 2.—Two white-sided guinea-pigs were taken and prepared for inoculation. To each animal was given 0 *75 c.c. of C.S.L. antistreptococcal serum, subcutaneously, about ten minutes before inoculation with the suspension. To one animal 0 *8 c.c. of diphtheria antitoxin (500 units) was also given subcutaneously. The animals were then inoculated intradermally with 0 *2 c.c. each of emulsions of four field-cultures, and also, posteriorly to those inoculations, with 0 *2 c.c. of a known pure strain of K.L.B.

At the end of 24 hours the lesions were observed, and were found to be very »lightly modified in the ease of two out of the four emulsions tested in the control animal.    .

The animals were observed at the end of 48, 72, and 96 hours and results recorded.

It was found that, in two cases out of the four, the obscuring reactions were sensibly diminished, and also, very slightly, in the third. In all cases, however, the diminution was not sufficiently marked to render the reading of results much easier to an inexperienced worker. This is not to be wondered at, when one takes into account the number of pus-forming and infective organisms present in the normal throat swab.

As in nearly every culture there were found rapidly-growing staphylococci, and as many skin lesions sliow’ed the presence of pus-forming organisms of a similar type, it was decided to give anti-staphylococcal serum in conjunction with the anti-streptococcal serum to the animals. Accordingly, all animals used were given 1 c.c. of mixed anti-staphylococcal and anti-streptococcal serum (C.S.L.), subcutaneously, two hours before the intracutaneous test was performed. Later these injections were given intra-peritoneally to ensure more rapid action. The control animals received, in addition, 500 units diphtheria antitoxin (C.S.L.), equivalent to 0 *8 c.c., as before mentioned.

The eflect of this measure was much more marked and a large number of the tests were considerably modified, the proportion of doubtful result« being accordingly reduced.

In some cases, however, large lesions persisted in both normal and control animals, and were not unlike diphtheritic lesions in appearance. Smears from these lesions, when cultured and examined, revealed a Grain-positive organism resembling Pfeiffer's bacillus.

Some animals died from spreading sepsis, and in others larger necrotic areas appeared, which showed a tendency to spread. In other animals again, an intense and wide-spread hyperaemia with oedema infiltrated the tissues even beyond the shaven area. This was especially intense towards the abdomen, as the tendency was for the oedema to gravitate.

In many instances, however, the true “ target ” lesion was observed, as described, uncomplicated.

In the majority of cases, nevertheless, the reaction proved to be mixed, with an inflammatory centre and a white marginal zone, which later became purple with sloughing of the epithelium. This marginal zone was absent from the control animals, and hence a result could be read fairly easily.

In order to keep a check on the lesions, and also to render diagnosis more easy by providing a standard of comparison, occasionally an animal was inoculated with a field-culture reported negative, to which had been added in suspension a pure B. diphtherias strain, known to be virulent, as in Experiment 1. The animal was, of course, protected against staphylococcal and streptococcal infection, but received no diphtheria antitoxin.

Smaller modifications, especially in technique, were made from time to time, necessitated by the large number of daily tests required and the need for timesaving involved in keeping pace with the swabbing.

The emulsions used were not compared with a standard emulsion, but a less accurate method was employed. Amounts of saline, varying from 1 «5 to 2 •5 c.c., were added to the culture tubes, the quantity varying according to the luxuriance of growth, and in some cases the proportion of diphtheria-like organisms roughly known to be present. The surface growth was then scraped off and emulsified as before, and the strength of the emulsion estimated b}T the eye.

The “ follow-up " injection of 500 units diphtheria antitoxin recommended by Eagleton and Baxter, to be given four or five hours after the test, was omitted. These authors claimed for the injection the saving of the lives of the animals; but, in our experience, very few animals, if any, were killed by the action of diphtheria toxin, but rather by intercurrent toxaemias from massive spreading infections. When protected against these foreign organisms they rarely died.

According to our experience the success of virulence tests, when done in large numbers of cultures and against time, is mainly dependent on two factors. Firstly, the proper immunization of animals against infection by interfering organisms ; and, secondly, experience in reading the tests.

Practical Application of Results of Test.

In the event of a strain being proved avirulent the municipal authorities were notified to that effect, and the subject was released from quarantine and was permitted to reattend school, no further swabs being taken.

The wisdom of this measure depends, of course, on the constancy of virulence or avirulence of any given strain of bacilli.

The vast majority of modern workers in diphtheria are of the same opinion on this matter, namely, that a strain proved avirulent will remain so under all conditions of environment.

Only two writers of recent years, Meader and Ladendorif, have laid claim to having changed the virulence of diphtheria bacilli. Accordingly, it is considered that carriers of proved avirulent germs are not in any way a menace to public health, and may safely mix with their neighbours.

Results of Tests.

In all 158 tests were made during the campaign by this method. Of these 120 were completed, of which 51 indicated positive virulence and 69 negative, showing a percentage of 42 *5 positive.

The figures for separate schools are shown in the following table :—

Table 8.—Results of Virulence Tests by Schools.

School.

Number of Completed 1 este.

Positive.

Negative.

Percentage

Positive.

Gravel Hill S.S. .. .. ..

15

7

8

46-6

Golden Square S.S. .. .. ..

18

6

12

33 3

Violet-street S.S. .. .. ..

39

17

22

410

Quarry Hill S.S. .. .. ..

10

5

5

50 0

Town Hall, Bendigo .. .. ..

4

m #

4

Central School .. .. ..

27

15

12

55*5

Eaglehawk S.S. .. .. ..

1

# #

1

Specimen Hill S.S. .. .. ..

4

1

3

25*0

Kae’s Hill S.S. .. .. ..

1

1

St. Li bonus’ School .. .. ..

1

• •

1

• •

Total .. .. ..

120

51

G9

42*5

In 101 instances the emulsions were made from a mixture of cultures from both nose and throat, the bacilli having been found in both. In 40 cases the emulsions were made from the nose cultures only, and in 17 cases from the throat only.

Of the total, 120 definite readings were ultimately obtained, although in many instances two or more tests were required to arrive at a conclusion.

In the 38 instances in which a definite reading was not obtained fresh positive cultures were not obtainable, owing to the carrier condition clearing up in the meantime.

In the case of 14 strains the guinea-pigs died in 48 hours or less, necessitating fresh tests being done.

In 24 cases masked reactions occurred to a sufficiently serious extent to prevent readings being made.

Of the 40 nasal strains tested only 3 were found virulent, while in 9 cases it was not possible to obtain a result. This gives a virulence percentage of 11 *5.

Of 17 throat strains 6 were found virlent and 4 avirulent. In 7 the tests were uncompleted. Thus 60 per cent, of the throat strains were found virulent.

In 101 cases, where both nose and throat strains were tested together, 42 were virulent and 39 avirulent, while 20 were not completed. The percentage of virulent strains in this series is 51 *9.

These results are shown in tabular form as follows :—

Table 9.—Location of Virulent Strains of Bacilli.

Strain.

N umber Tested.

Incomplete.

Virulent.

Avirulent.

Percentage

Virulent.

Nose .. .. ..

40

11

3

26

11 «6

Throat .. .. ..

17

7

0

4

60*0

N080 and throat .. ..

101

20

42

39

51*9

This table is interesting, in view of the figures quoted earlier, showing that after the first swabbing a very large percentage of children were nasal carriers only.

It was noted during the examination of the swabs that Hoffmann’s pseudo-diph. bacillus was especially frequently observed in the nasal swabs, and, on that account, it seems likely that a great number of diphtheroid bacilli, closely resembling the Klebs-Loeifier bacillus morphologically, must frequent the nose.

Age Incidence.    ‘

The following table shows the age and sex distribution of carriers in which the virulence of strain was tested :—

Table 10.—Age and Sex Incidence of Carriers Tested for

Virulence of Strain.

Sex.

Aiie in Years.

5.

0.

7.

8.

0.

10.

n.

12.

13.

14.

Not

Stated.

Total.

Virulent .. ..

M.

3

3

5

3

2

1

3

1

1

1

23

F.

2

2

3

4

2

G

5

3

1

• •

• •

28

Total ..

• •

5

5

8

7

4

7

S

4

1

1

1

51

A virulent ..

M.

2

4

4

5

3

3

3

2

2

G

34

F.

3

G

4

4

2

6

G

2

1

• •

1

35

Total ..

• •

5

10

8

9

5

9

9

4

3

• •

7

G9

Total .. .. .

• •

10

15

1G

16

9

16

17

8

4

1

8

120

Percentage virulent

• •

50

33

50

43

44

43

47

50

25

100

12*5

42-5

It will be observed that neither age nor sex of carriers has any apparent influence in determining the likelihood of strains being virulent, as the percentage of virulent strains remains fairly uniform up to the age of thirteen, and in both sexes, and the figures for the ages beyond that are too small to permit of conclusions being drawn.

As it will be seen from the percentage curve of carriers the likelihood of a child being a carrier after the age of twelve or thirteen is small, and diminishes rapidly with each added year of age.    .

It is, therefore, presumable that the age of the host does not in any way influence the virulence of the bacilli.

Conclusions.

From these tests one gathers that, of the germs morphologically classed as B. diphtheria cultured from the throats and noses of school children of the Bendigo district, only 42 *5 per cent, are to be classed as virulent, and therefore capable of causing clinical diphtheria.

It also appears that the bulk of virulent germs inhabit the throat rather than

the nose.

This is interesting, in view of the great frequency with which the bacilli are found in nasal cultures, or rather the regularity with which they persist in the noses of carriers, as mentioned earlier.

The third fact gleaned from these figures is that age of the host bears no relation to the likelihood of virulence of strain.

Regarding the method of testing, once the problem of immunizing the test animals against extraneous infections is solved, the intracutaneous method used is very satisfactory ; experience is necessary in reading the tests, as in any technical procedure of similar nature.

The giving of intradcrmal injections is not difficult when care is taken and if a fine needle is used. The gauge should be about No. 26 (American) or finer, if obtainable. An all-glass I c.c. syringe is the best type to use ; those used for these experiments being of the “ Vim ” manufacture, and having proved quite satisfactory.

it is regrettable that the amount of work to be done in this section, and the necessity for the saving of time, prevented a fuller investigation being made into the question of extraneous sepsis and toxaemia in the animals used.

The value of virulence testing is, of course, unquestioned, but in campaign work where large numbers of individuals are to be swabbed, it is especially valuable.

The carrier of a virulent organisms, in the absence of this test, may be kept away from school or occupation needlessly for a period of months.

In dealing with large numbers the question of saving of time and staff comes into play, and therefore a method of virulence-testing which eliminates the necessity for a preliminary isolation of a pure strain of bacilli is of extra value, as it bears a relation to both these factors.

III.—SCTIICK TESTS.

Development of the Test.

Prior to the introduction of the intradcrmal test for susceptibility to diphtheria by Schick in 1913, experiments had been in progress for some time on the question of active immunization against that disease by means of a mixture of toxin and antitoxin, but no satisfactory method of testing the alleged immunity produced had been forthcoming.

In Schick’s test we have not only the means required for testing the degree of active immunity produced by any measure taken, but also, if applied before immunization, the means of discrimination between those already naturally immune from and those susceptible to diphtheria, and therefore requiring immunization by artificial means.

In an article published in the Munch. Med. Wochenschrift (ix., 1913, pp. 2608-10), Schick stated that newly-born infants, when tested, were shown to be immune against diphtheria in the vast majority of instances. The immunity probably diminishes, however, until the age of three or four years, at which period the child is most likely to be susceptible. From that point susceptibility gradually diminishes as age progresses, and. among adults, the majority are immune.

Schick’s own figures are tabulated as follows

From 6-12 months . .    . .    43 per cent, are susceptible.

1-5 years    . .    . .    60    ,,    ,,

,,    5 15 years    . .    . .    50    ,,    ..

W. H. Park, of New York, gives a more elaborate set of figures as a result of his tests, which bear out Schick s statement, t hat children under three or four years are less susceptible than children between the ages of four and ten.

Park's table is as follows :

Under 3 months . .

. . 15 per cent. susceptible

From 3 6 months . .

• • 30 „ „

., 6-12 months ..

. . 60 ,, ,,

., 1-2 years ..

.. 70 „ „

., 2-3 years . .

.. 60 „

.. 3-5 years . .

• • 40 „

,, 5-10 years . .

. • 30 „ „

„ 10-20 years . .

• • 20 ., „

Over 20 years . .

• . 15 ., „

Park urges, therefore, that children under three years should be retested at intervals.

McClelland, in the Ohio State Mediad Journal (Yoi. xix., No. 5, May, 1923), publishes a report on a series of 6,893 tests in Cleveland, Ohio, on school children, of whom a very large percentage were in the kindergarten stage.

He found that 4,307, or 62 *5 per cent., of the whole were Schick-positive, while in the younger children the positive percentage ran as high as 85 per cent, in certain areas.

Phis worker also investigated the statement by Schick that, in congested districts, a smaller percentage of positives was observed, and obtained results in support of Schick's contention.

N ATUHAL I MM UNIT Y.

Natural immunity to diphtheria is due to the presence of natural diphtheria antitoxin in the blood. According to Schick, at least one-thirtieth unit DAT in each cubic centimetre of the blood supply is necessary to prevent the reaction occurring. Von Behring states that one-hundredth unit is sufficient.

Publicity Methods for Initiating the Campaign.

W hen it was proposed to conduct a trial of the Schick test and active immunizing process on the Bendigo school children, one realized that the greatest difficulty would lie in the direction of overcoming not only public apathy, but also a certain measure of antagonism to any new inoculation test. r.5745.—3

Accordingly, a series of articles was published in both the local daily papers over a period of some weeks before it was proposed to commence the tests. The local medical men were asked to give their support to the campaign by advising parents to have their children tested, and two different meetings of schoolmasters were addressed, and were given a more or less detailed description of the process and its advantages.

It is considered now that this measure was very largely responsible for the good percentage of volunteers. The headmasters were undoubtedly responsible for the decision of a large number of the parents.

In order to check the numbers and at the same time to gain a written consent from the parents, a form was drawn up (Form II.) at the Health Laboratory and printed by the municipality of Bendigo over the signatures of the Town Clerk and the Medical Officer of Health for that city, setting out simply, but clearly, the method of the test and the immunization process, and urging the parent, in the interests of public health, to give consent to the process being carried out on his or her child.

The lower portion of the form, which was detachable, contained a formal consent for signature.

Every child at school was given a form, and was expected to return the detached portion, signed or not, to his or her teacher by a certain date.

Out of 5,761 children, which is approximately the total school attendance for Bendigo and Laglehawk, 1,616 consents were obtained, equalling 28*05 per cent.

In actual performance 35 tests were not completed, due to absence of the child from school for some reason or another.

Twenty-five schools were visited within a radius of about 4 miles in each direction.

Preparation of the Toxin.

The material used for the test was Commonwealth Serum Laboratories diphtheria toxin, prepared from the known toxin strain, Park No. 8.

One c.c. of this toxin contained 35 M.L.D., and, as it would not keep in diluted form, it was necessary to dilute a fresh supply over night and keep it on ice for use on the following day.

The dilution was made in the ratio of 1 M.L.D. to 10 c.c. of sterile normal saline solution, 50 to 200 doses, as required, being made up at a time. The dose for one injection was 0*2 c.c., equal to one-fiftieth of an M.L.D. for a 250 gramme guinea-pig,

A control was used, in the shape of the same toxin, heated to 75° C. for ten minutes, and diluted in the same ratio. The heating destroys the toxic action and readers the detection of pseudo-reactions easy. The control dose used was the same as that of the normal, viz., 0 *2 c.c.

Both control and toxin were put in sterile 50 c.c. serum bottles, fitted with special rubber corks, through which the fluid could be withdrawn by hypodermic syringe without the bottle being opened or the contents being exposed to contamination.

Importance of Fresh Dilutions.

In order to secure uniformity in reading results, it is most important that the toxin and control should be freshly diluted preparatory to making each day s tests. It is not considered reliable to use toxin which has been diluted for more than 24 hours, even if it has been kept on ice when not in use.

In certain schools in which toxin diluted for more than 24 hours was used, the percentage of total positive readings was somewhat lower than the average. At the same time it is considered that, even using toxin diluted for as long as 48 hours, a reading will be obtained in the great majority of susceptible cases, as the percentage of readings indicating the mildest grade of reaction was considerably higher in the case of these schools than in others.

Technique of Tests.

The tests were performed by Dr. ii. E. Butchart and myself. Dr. Butchart used the toxin on the right arms throughout, while I used the control on the left arm throughout.

Preparatory to the tests an outfit was collected, which comprised—

Two 1 c.c. “ Vim ” all-glass syringes, sterilized, contained in sterile test tubes with cotton-wool plugs.

One glass jar, with ground-glass stopper, containing two dozen No. 2G (American) gauge hypodermic needles in absolute alcohol. These needles were chosen with a short bevel.

One bottle diluted toxin (labelled in black).

One bottle control toxin (labelled in red).

One spirit lamp.

One pair sterile forceps.

One bottle ether, with quantity of cotton-wool for preparing arms.

Two assistants were requisitioned at each school, one to clean the arms of the children and the other to act as clerk and checker.

The first was instructed to rub the flexor surfaces of both forearms of the children with cotton-wool soaked in ether.

The second wrote the names in the note-book, after checking from the consent slips, and took particulars of age, sex, and also previous history of having had diphtheria or of having been a carrier.

The children were marched past our table, and the tests were performed at the rate of 100 to 150 per hour.

The actual inoculation is accomplished by keeping the needle almost parallel to the skin, with the bevel upwards. The skin is put slightly on the stretch, and the needle inserted slowly until the proximal edge of the bevel disappears under the surface. The plunger of the syringe is then pressed steadily and, if the position of the needle is correctly intradermal, a white bleb appears, very often pitted by the hair-follicles in such a manner to resemble a white orange skin. The dose of 0*2 c.c. usuallv forms a bleb of about 10 mm. in diameter, or less. This varies according to the nature of the skin of the patient. The inoculations are painless, and in no case in our series did I see a child crying nfler the test had been performed.

The needles are sterilized by dipping in alcohol and flaming in between each inoculation. Xo septic needle-tracks occurred.

No dressing is required for the arms, and the child may be instructed that no special care need b<* taken, beyond abstention from scratching.

Rkadi xo Results.

The arms were inspected on the fourth day, and again on the tenth or eleventh day.

As we were dealing with school children over a large area, it was not practicable to observe them at any other places than at the schools : consequently only five da vs per week were available for work of this nature, this precluded the possibility of observing tin* arms daily for the first three or four days, as advised by some writers.

Positive reactions were arbitrarily divided into three grades, according to severity. These were recorded as . and + . Dr. Butchartand I examined all the arms together at each time, and agreed as to the result before recording.

The second reading was taken as the correct one, on account of the tendency of the four days' reading to be obscured by pseudo-reactions.

Nature of Reactions.

in the case of a full positive ( r) reaction at the end of four days, the lesion presents itself as a raised circular area, 20 to 40 mm. in diameter, or even larger in some cases. It is bright red in colour or reddish-brown, and both the intensity of the colour and the raising are more marked at the edges, the centre being somewhat paler, and more nearly approaching to normal skin in appearance.

In one or two instances of very marked reactions blebs were observed in the central area, filled with clear yellowish serum, but no pus was seen in any reaction. Many opportunities presented themselves for observation of lesions on all days after the fourth, owing to the difficulty of making a time-table which allowed a visit on the tenth day to each school.

From the fourth day onwards the lesion lessens in intensity and the colour changes towards a purple. The epithelium forms white powdery flakes, which can be rubbed off, leaving a dark purplish pigmented area beneath. This change takes place during the fifth to the twelfth day, and usually, at the twelfth day, all that remains is the widening ring of epithelial flakes with the deep purple patch in the centre.

This pigmentation was observed in some cases as long as two months later, very much less in intensity.

No reaction should appear on the control arm.

These lesions are painless, but a certain irritability of the skin is present during the first week. Consequently certain of them were artificially modified by scratching.

The second grade of reactioii (4-) presents very similar characteristics in a milder degree. The colouration is not so marked, the area of reaction is not so wide, and the lesion is not raised up to the same extent. In this grade the annular border is not very distinct; at the end of ten days, however, the reaction is very similar in appearance to the full positive at that period. The desquamation and purple discoloration are quite well marked, and the latter seems to persist for the same length of time.

In the least-marked reactions ( + ) very slight redness and induration over a small area, 10 to 20 mm., are present at the first reading, almost indistinguishable at times from the needle-track on the control arm. At the end of ten to twelve days, however, these reactions are easily distinguished by the presence of definite desquamation and some purple pigmentation, which are not present in the control test.

The distinction between these grades of reactions is purely arbitrary, but its usefulness will be seen later on in the statistics. It is considered that the severity of reaction bears a distinct relationship to the degree of susceptibility to diphtheria in the host.

All cases showing any degree of positive reaction were classed as susceptible, and were advised to undergo the immunizing process.

Pseudo-r e actio xs.

Reactions occurring in both arms are frequently met with and, in many cases, mask a positive reaction for some days. The incidence of these will be discussed later. They occur as a diffused blush around the site of inoculation, and vary greatly in size and intensity.

it may be said, in general, that pseudo-reactions are more extensive than the true toxin reactions, as, in the case of their masking a positive, the out line of the latter can sometimes be traced well within the outer limit of the false reaction.

Pseudo-reactions do not present a definite edge, the hyperaemic condition merging gradually into the normal skin, and, moreover, they do not present a uniformly circular shape, but are usually more oblong, the long sides corresponding with the direction of the needle-track.

There is usually a certain amount of tumefaction in the centre.

These reactions usually disappear in four or five days, but sometimes persist a day or two longer. They never interfere with the ten-day reading of the test. Their presence is attributed to a local anaphylaxis caused by the protein substance of the destroyed bodies of the bacilli in the toxin and by proteins from the broth used in culturing. This is entirely distinct from the action of liberated toxin.

Pseudo-reactions must not be confused with a third type of reaction, which occurs in some cases and is urticarial in nature.

This reaction takes the typical urticarial form of a wheal or raised area, and occurs within a few hours of the inoculation. It disappears within 30 or 48 hours.

Statistics.

In our series of 1,616 children 35 tests were not completed, leaving 1,581 completed tests.

No. of Scholars.

No. of

Percen

tage.

No. of Incomplete Tests.

Positive Reactions.

Negative.

Pseudo-reactions.

Aver

age

Age.

No.

School.

Volun

teers.

Total.

Percen

tage,

Total.

Percen

tage.

Posi

tive.

Nega

tive.

Total.

Percen

tage.

1

Camp Hill Central

684

255

37*3

10

93

31

16

140

57-0

105

430

23

9

32

13 * 1

9*5

2

Gravel Hill S.S.

512

144

28*1

2

57

14

8

79

57 *6

63

42-4

7

8

15

10-5

7*9

3

Violet-street S.S.

535

166

31 0

3

51

14

17

82

50 3

81

19*7

6

14

20

12-2

8 *5

4

Rae’s Hill S.S.

149

40

26*9

2

11

3

6

20

52-7

18

47-3

1

4

6

13*2

11-8

5

Specimen Hill School

96

4

4*2

• •

• •

• •

1

1

25 0

3

75-0

..

..

..

..

8-2

6

St. Killian’s School

330

60

18*1

1

19

4

2

25

42-4

34

57-6

0

# *

o

éu

3-4

8*5

6

Bendigo North S.S.

221

56

25-3

, #

10

3

5

18

32-2

38

67-8

2

2

4

7-1

8*3

8

Quarry Hill S.S.

290

80

27*6

v *

13

11

12

36

45 0

44

55-0

3

2

5

6*2

8-1

9

Domestic Art Centre

133

23

17*3

, ,

2

3

2

7

30-4

16

59*6

2

1

3

13-0

12*5

10

Long Gully S.S.

168

62

36*9

2

11

4

9

24

400

36

60-0

1

6

7

11-6

8*4

11

Bendigo East School

81

47

58'0

1

6

8

4

18

39-1

28

60-9

1

2

3

6 5

9*2

12

Golden Square School ..

476

136

28-6

2

19

16

20

55

41-0

79

59-0

5

6

11

8-3

9-0

13

White Hills S.S.

99

47

47*6

1

8

14

o

¿4

24

52*2

22

47-8

..

• •

..

..

8-3

14

White Hills R.C. School

38

8

21 *6

, ,

, ,

1

4

5

62-5

3

37-5

..

• •

» •

..

7-7

15

Convent of Mercy

90

18

20-0

* #

5

3

1

9

50-0

9

50-0

1

• •

• •

5*5

9*8

16

Girton C.E.G.G. School ..

60

21

35-0

2

1

3

6

10

52-6

9

47-4

1

1

2

10-5

10-8

17

Eaglehawk North School

76

27

36-8

1

8

1

2

11

42-3

15

57-7

l

2

3

11-6

8-7

18

St. Liborius’ R.C. School

100

7

7*0

1

1

• •

2

28-6

5

71-4

..

1

1

14*3

9*1

19

California Gully

120

26

22*5

# ,

9

1

3

13

50-0

13

50 0

• .

1

1

3*8

8-4

20

Eaglehawk Central School

487

132

27*5

7

38

13

14

65

520

60

48*0

3

6

9

7*2

10-5

21

Marist Brothers School ..

245

35

14*2

1

7

5

0

é*

14

41-2

20

58-8

« •

1

1

30

11-5

22

St. Joseph’s School

156

28

17*9

1

6

2

5

13

46*4

15

53*6

1

..

1

3*4

8 4

23

Bendigo High School

306

50

16*0

#

2

2

7

11

22-0

39

78-0

3

1

4

8-0

15-4

24

25

Bendigo Technical School

St. Aidan’s Orpkange (not pre-

194

29

14*9

• •

• •

5

5

10

34-4

19

65*6

4

• •

4

13*8

12-7

viously tested)

26

26

100 *0

•.

6

1

1

8

30-7

18

69-3

2

2

4

15-4

7*2

• •

Unattached

• •

1

• •

• •

• •

1

• •

• •

• •

• •

• •

• •

• •

• •

3*5

26

Totals (not previously tested) St. Aidan’s (previously tested and

5,673

1,528

26-9

35

383

164

154

701

47-1

792

52-9

69

69

138

9-0

9*1

partly immunized)

88

88

100-0

• •

7

13

4

24

27-3

64

72-7

16

7

23

26-0

10-8

!

Grand totals

5,761

1,616

28*0

35

390

177

158

725

45-9

856

54-1

85

76

161

9-9

9*3

Positive reactions were recorded as follows :—

+

. * . .

..

.. 390

±

- * . .

• •

.. 177

±

.. ..

• •

.. 158

Total positives

.. 725

Negative reactions, 856.

Thus the percentage of positive reactions was 45 #92 per cent.

Of the total, 88 children from St. Aidan's Orphanage had been tested during 1922, and had, where positive, received some amount of toxin-antitoxin immunizing mixture.

Some of the children received one injection only, and some two ; but in no case was the complete series of three injections given. The statistics of the work are, unfortunately, not available, and consequently definite conclusions on this point may not be drawn. This series of 88 cases will be treated separately from the bulk.

Their average age was 10 *8 years. Among them positive reactions occurred

as follows :—

+    ..    ..    ..    7

±    ........13

+    ..    ..    ..    ..    4

Total positives    ..    ..    24

. Negative reactions, 64.

Percentage of positive reactions, 27 *3 per cent.

This shows a marked decrease from the average of children who had not

been treated. Also, it may be pointed out that the percentage of full positives

(+) is very much less than in the normal series.

The average age is higher,

but not sufficiently

so to account for the drop.

Among 1,493 completed tests on the remainder, the positives were read as

follows :—

+

• • 00 00

.. 383

it

m* 00 00

.. 164

+

0 0 0 0 0 0

.. 154

Total positives ..

.. 701

Negative reactions, 792.

Percentage of positive reactions, 46 *96 per cent.

Average age, 9 *375 years.

This percentage agrees fairly closely with Schick's estimate (5-15 years, 50 per cent.), and is higher than Park's (5-10 years, 30 per cent.).

The average age of the children rather precludes comparison with McClelland's high general percentage of 62 *5 per cent., as he states that the large majority of his tests were performed on children of the kindergarten age.

Table 12.—Age and Sex-Incidence.

Grade of Reaction.

Sex.

Age.

Under

4.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14

Over

14.

Not

Stated.

TotaO.

Positive -r j

Positive i { Positive + | Negative — j

Totals

Grand totals

M.

F.

M.

F.

M.

F.

M.

F.

1

3

1

1 1

2 I

4

2

1

3

(5

9

11

10

7

6

3

15

8

20

33

12

4

4

10

35

23

18

30

10

10

4

6

46

42

29

25

8

8

5

8

58

39

35

25

11

7

12

14

43

39

13

19

8

7 6

8 45 42

23

20

8

13

14 7

58

59

14

19

7

5

13

4

53

42

9

7 11

8 9 9

45

20

3

2

1

3

3

11

12

1

2

2

3

12

19

2

6

1

3

9

5

203 J ***

73J 104

7y' 154 75 J 04

4o51 „qn

357/

.M.

F.

5

5

8

8

-10

29

71

70

78

88

100

80

101

85

72

76

103

99

87

70

74

44

18

17

16

23

12

14

~65\ | iQq

708j

• •

10

16

69

141

166

180

186

148

202

157

118

35

39

26

1,493

The age-incidence per cent, has been plotted on Graph III., and shows a curve corresponding fairly closely with the figures of Schick and Park for all positives.

At under four years, in a series of ten cases only, the total percentage of positives is 70 per cent. The number of cases is larger from that point on to fourteen years. Over fourteen the cases are grouped together again.

From 70 per cent, the curve drops to 20 per cent.

The curves of the three arbitary grades of positive reaction have also been plotted and show some interesting points.

Starting with the full positive (+) at under four years of age 40 per cent, is registered, and from there the curve follows fairly accurately the curve of the total positives, about 20 per cent, below it, till, at over fourteen, only 2 *5 per cent, show a full positive reaction.

The curve of the second grade of reaction (i) starts at 20 per cent., and remains fairly even throughout, at over fourteen 5 per cent, being shown.

The + curve, on the other hand, shows an up-grade from nil at four to 12 *5 per cent, at over fourteen.

This shows that, as age advances the likelihood of a positive reaction definitely diminishes, and also that as age advances the severity of reaction is likely to be less.

Graph III. Percentage of Positive Reactions and Pseudo-Reactions with Age Incidence.

Sex Variation.


The sex variation is shown in Graph IV., compared with the total incidence of positives and the positive incidence of the 88 partially immunized children mentioned previously.

Of 785 male children 350, or 44 *6 per cent., were Schick-positive, and of 708 female children 351, or 49 -6 per cent., were Schick-positive. The average of the boys, viz., 9 *49 years, as compared with that of the girls, 9 *21, is not sufficient to account for the variation.

Influence of Consanguinity.

A strong tendency for children of the same family to be classed in the same group was noticed during the tests. Definite statistics on this subject were not obtained, owing to lack of time, but in many instances it was noticed that three or four children of the same family were all either Schick-positive or negative.

On the other hand, out of three sets of twins who were subjected to the test, in two instances one turned out to be Schick-positive, while the other was Schick-negative.

Previous History of Diphtheria.

Of 302 children who gave a previous history of having had diphtheria 130, or 43 per cent., were Schick-positive, showing a small decrease from the average. It would appear from this that the immunizing effect of one or more attacks of diphtheria is small.

Reactions of Carriers.

Of 147 children who gave a history of having been carriers during 1922 or 1923 63, or 42 *8 per cent., were Schick-positive. This also would lead us to infer that the fact of being a carrier does not indicate the likelihood of being immune from diphtheria.

A search through the records of the campaign revealed that, in two instances, Schick-positive children were proved to be carriers of virulent diphtheria bacilli.

In all other instances where carriers were submitted to the Schick test, and where a virulence test was performed on their bacilli, in the event of the child being Schick-positive the bacilli were avirulent; conversely, if the bacilli were proved virulent, the carrier was Schick-negative.

At the same time these two atypical instances prove that it is possible for a susceptible child to harbour virulent bacilli in the throat or naso-pharynx. In neither case did the child develop diphtheria, although in one case the child gave a history of having had diphtheria in 1922. In both cases the reaction was =[=. Further reference will be made to these cases.

Pseudo-reactions.

Altogether 161 instances of the occurrence of pseudo-reactions were recorded, ecpialling slightly over 10 per cent, throughout.

Of these, however, 23 occurred among the 88 children who had been previously tested, giving a percentage of 26 *1.

Of this series of 23, sixteen occurred in those showing a positive reaction, while the remaining seven were found in those giving negative reactions.

Of the remaining 138, an incidence of 9 *03 per cent, of the 1,493 tests, 76 masked positive reactions and 62 were associated with no other reaction.

-Comparing the first number 76, with the 45 per cent, of total positives, it would appear that a pseudo-reaction is somewhat more likely to occur in a Schick-positive than in a Schick-negative.

This is much more easily realized by looking at the figures in the previous series of the 88 previously tested and partially immunized children, with 26 per cent, of pseudo-reactions, of which two-thirds masked positive reactions. It would appear in this series that the giving of immunizing injections heightened the anaphylactic tendency to produce pseudo-reactions.

Age- and Sex-Incidence of Pseudo-reactions. rI he age-incidence table of pseudo-reactions shows that these reactions are rare up to the age of six or seven years. From then on the curve rises till the age of nine years, and then remains fairly constantly at 10 per cent.

Table 13.—Age-incidence Table of Pseudo-reactions.

A .re.

Grade of Rent-non.

Under

4.

4.

7.

8.

51.

10.

11.

12.

IT

14.

Over

14.

Not

Stilted.

f<*i ,lN.

Positive + ..

3

2

4

3

4

4

1

21

Positive dl • •

. .

. .

..

. .

l

1

7

2

6

2

5

1

I

26

Positive i ..

. .

. .

..

1

3

4

4

4

5

4

3

, ,

1

29

Negative —

• •

• •

1

5

3

10

4

12

8

G

6

3

3

I

62

Totals ..

• •

• •

1

0

10

lo

17

22

22

16

18

4

5

2

138

Sex Incidence.

Seventy-two pseudo-reactions were observed in males and 66 in females. Allowing for the fact that 785 males and 708 females were tested, this shows a remarkably even sex distribution, the girls being slightly more prone than the boys. The percentage of the boys is 9 *01, as against 9 -3 per cent, in the case of the girls.

A Doubtful Case of Diphtheria in a Boy Recorded as

Schick-negative.

An interesting case may be mentioned here which occurred during the progress of the campaign.

A boy, aged fourteen, was tested in April and was found to be Schicknegative. On the 1st June he was taken ill and sent to hospital as a doubtful case of diphtheria.

The Medical Superintendent of the hospital states that the case did not closely resemble a true diphtheria, and the first swab when examined did not reveal the presence of K.L.B.

The second and third swabs, however, were positive, and his condition rapidly improved after the administration of D.A.T.

The fourth and fifth swabs were negative, and he was discharged from hospital on 17th June, after an uneventful recovery.

The points of interest regarding this case are, firstly, the doubt as to the true clinical nature of the malady.

The boy was Schick-negative, and the first swab did not show B. diphtheria . although the second and third swabs did. It is my opinion that, if the case had been true diphtheria, there would have been no difficulty in detecting characteristic bacilli in the first swab.

On the other hand, these bacilli were plentiful in the second and third swabs, and the patient improved rapidly after the administration of diphtheria antitoxin.

It is regretted that an opportunity was not afforded for conducting a virulence test on the strain, but the case only came under my notice on the day of his discharge from hospital.

A second point of interest in connexion with this case is brought under notice by a summarized article in the British Medical Journal of 19th May, 1923, p. 73 (No. 3255), in which P. II. Kramer reports the cases of two Schick-negatives who both subsequently underwent severe attacks of diphtheria, in one instance complicated by paralysis of the palate.

Both these cases were those of sisters in a diphtheria ward at the Rotterdam Municipal Hospital, and were, on that account, exposed to a more massive infection than the average person.

Comparison between the latter cases and the one quoted above shows several divergent factors, the ages of the patients and the atypical nature of the first case being chief among these.

The first-mentioned case was that of a pupil at the Bendigo Technical School, at which place 29 tests were performed. Ten of these were positive (34 per cent.), which is not a very low percentage when the average of the boys, 12 *7 years, is taken into consideration. Five of the tests were and the remaining five +, none showing the full reaction. rJ he toxin used in this school had been diluted over 24 hours, but for less than 48 hours at the time of making the tests, and it is not considered likely that susceptibles were overlooked.

IV.—ACTIVE IMMUNIZATION.

The Development of Methods.

Park, Schroeder, and Zingher in 1913 first began a systematic immunization of susceptibles with a toxin-antitoxin mixture, checking their results by the Schick test. This was done in New York.

They found that, after two injections of 1 c.c. each, 50 per cent, of susceptibles were rendered immune from diphtheria, and that, after three injections of the same amount, over 80 per cent, developed immunity.

They were ultimately able to immunize all Schick-positives, and the immunity, with very few exceptions, has endured for six and a half years, according to their statement, made to the American Public Health Association at Cleveland in October, 1922.

This period is sufficient to carry the child of average school age. up to the age when natural immunity is a probability, and, moreover, in all probability, the artificially induced immunity will prove to be permanent.

Passive immunity, produced by simply inoculating with diphtheria antitoxin, is not lasting, the average duration being less than five weeks. This is due to the fact that the antitoxin is the product of the cells of the horse, and is quickly eliminated by the human body. If subsequent injections are given, the immunity disappears twice as quickly.

In searching for a more permanent method of inducing artificial immunity, the idea of mixing toxin with antitoxin was evolved, following out Ehrlich's theory of immunity.

The toxin is the active agent producing immunity, while the antitoxin is the agent which protects the body against toxic action.

i he toxin and antitoxin enter into a chemical combination of such a nature as to permit the immunizing action of the former, while not interfering with the protective action of the latter.

Thus the presence of antitoxin enables the body to bear a larger amount of toxin than would otherwise be possible. (Heineman and Hixson, Jl. of Infectious Diseases, Yol. xxx., No. 5, p. 508, May, 1922.)

The toxin and antitoxin are mixed in proportions, which give a slight excess of free toxin. This proportion is found to yield better results than an equally-balanced mixture, and still better than one in which an excess of antitoxin exists.

The occurrence of disagreeable reactions, both local and general, is governed by the amount of foreign protein present, i.e., bacillary substance, broth proteins, &c. Thus the more potent the toxin used the smaller the quantity required in an immunizing dose, hence the less foreign protein an 1 the less reaction.

Park and his co-workers, experimenting with different amounts of toxin, but always neutralized with antitoxin to the degree that 1 c.c. of each mixture produced tlie same toxic effect on guinea-pigs, found that the best immunizing results, accompanied by the least local reactions, were obtained by the mixture containing four fatal doses (M.L.D.) of toxin.

With this mixture no marked local reactions occurred.

The toxin-antitoxin mixture was first used on human beings on 8th May, 1913, by Behring, but the immunity index as assessed by the Schick test was not used by him then. This mixture was known to be effective in immunizing animals some time before this.

r\ he reasons for delay in its use on humans were, firstly, the fact that the immunity took several weeks to develop in animals ; secondly, that in animals immunity lasted only two years ; and, finally, that the Schick test had not been published to determine susceptibility and to measure the immunizing effect produced.

Now that Park's figures show that the immunity produced is, in all probability, permanent, and although this immunity takes from three to six months to develop, this method, controlled by Schick’s test, is being widely used all over the world, and American figures show that the incidence of diphtheria is falling in the big cities in which work of this description is being carried out on a large scale.

V—

Procedure Adopted.

In the Bendigo campaign toxin-antitoxin mixture manufactured at the Commonwealth Serum Laboratories was used, and three doses were recommended to produce immunity, viz., J c.c., I c.c., and 1 c.c.

Accordingly, at the conclusion of the Schick testing, lists of positive reactors were drawn up, and each school's quota was forwarded to the respective headmaster, with a note intimating that visits would be made at certain dates for the purpose of inoculating, at the same time asking the master to secure the attendance of as many as possible of the subjects on those days. The inoculations were made at weekly intervals. •

Out of 725 positives there were nine children whose parents refused to allow them to undergo the course of inoculations, and one adult, a school-teacher, decided not to continue.

Of the remaining 715, 42 children were absent on the occasions of all visits through sickness or other causes.

Of the remaining 673, 579, or 87 per cent., of the total received the full course of three injections; 63, or 8 *7 per cent., received two injections; and 31, or 4 -3 per cent., received one injection only. In a number of these last-mentioned cases, the parents refused to allow the children to continue with the course.

Method.

The inoculations were made subcutaneously into the flexor surface of the left fore-arm. The ]eft arm was deliberately chosen to prevent interference with writing lessons.

The skin was cleansed with ether and the needles sterilized by alcohol and flaming, as in performing the Schick test.

The syringes used were as follows :—For the J c.c. injection, a 1 c.c. “ Vim all-glass syringe ; for the l c.c. and 1 c.c. injections, 5 c.c. and 10 c.c. “ Record ” metal and glass syringes. No. 26 American gauge needles were used.

The children, in a large 1 ulk of cases, made no objection to the inoculations, and did not complain of pain.

Reactions.

No serious reactions follow d the injections, although, in a few cases, moderately severe local reactions were observed.

In one instance only was there any marked reaction following the first injection of the seiies (£ c.c.) This was the instance of a boy aged twe.ve, who had experienced a very marked pseudo-reaction from his Schick test. In his case there was an area of swelling and hyperaemia covering about one-half of the fore-arm. and a circular area of small blebs around the inoculation site, about 1 inch in diameter.

The reaction had subsided in 48 hours and desquamation followed in the central area, as in the later reading of the Schick tests.

The second and third inoculations were followed by similar results in this

case, but no general reaction was manifest at any time.

The second inoculation of J c.c. appeared to be responsible for the majority of the more marked reactions.

Slight swelling and redness, accompanied by “ stiffness ” of the arm, all disappearing in 24 to 48 hours were complained of in 15 to 20 per cent of cases.

In a very small percentage of cases, cer ainly less than 3 per cent., moderate to severe reactions, accompanied by an extensive area of swelling and hyperaemia, occurred, with a small central area of blebs, like that mentioned previously.

In only two cases was any general malaise complained of, and in one case the subject complained of feeing “shivery” on the night of the injection All reactions had disappeared within 48 hours.

One case was observed on the day following the second njection, in which the arm showed very marked swelling and hyperaemia, with a centra area of 2 inches in diameter, occupied almost entirely by one large bleb, exactly resembling a bad scald.

At the time for the next injection the arm was normal, except for an extensive area of desquamation and some purple pigmentation around the needle puncture. The child voluntarily submitted to the third injection in this instance, and no reactio « followed.

In one case in which no reaction had followed the first injection, malaise and pain n the left side, toge her with local reaction in the inoculated arm, were complained of on the day following the second inoculation. The trouble eventually turned out to be Herpes zoster, and it is not considered that this is attributable to the T.A.T. mixture.

The final injection of the immunizing mixture was accompanied by no notable effects, only one or two children complaining of moderate reactions.

Eight through the series it was noted that reactions were entirely absent in the case of the younger children; the only reactions noted were in the cases of children over ten years of age.

One notable instance is the case of a headmaster of a school, aged 54, who volunteered for the Schick test and was found to exhibit a ^ reaction. He volunteered to undergo the immunizing process, and did so without showing the slightest reaction after any of the injections.

Those children who complained of severe local reactions were advised to loment the arms, and this measure was sufficient to allay the pain, although, aa mentioned before, no reactions occurred which were painful for more than 18 hours.

No sepsis occurred during the series.

Testing the Effect of Immunizing Injections.

At an interval of two months following the giving of the final toxin-antitoxin in ections, a further Schick test was performed on al available children who had received either two or the full course of three injections.

Immunity is stated to develop as a result of these injections, in from two to six months,-the time varv’ng in different individuals.

j o

As a delay of six months would have caused a clash with the Christmas vacation of the schools, and as the system of reading reactions in three grades used in the preliminary tests affords an opportunity of measuring a decrease in severity of re ction, presumably denoting a relative increase of immunity, the minimum period of two months was chosen in the interests of expedition. An added reason was the desire to keep the matter in view of the parents and to thus reduce the number of “ objectors ” to a minimum.

The tests were performed under the same conditions as previously. Children who had only received one immunizing injection were not re-tested, but all those a ailable who had received two or three injections were subjected to the test.

Of the 642 children in this class, 61 were either absent through sickness and other causes, or possessed parents who objected to hem receiving further inoculations.

Of the remaining 581, 533 had received the full immunizing course and 48 had received the first two injections only.

Two readings of the tests were taken, as nearly as practicable, on the fourth and tenth days.

No case of a full-grade (-f) reaction was noted in the whole series, and, altogether, nearly 90 per cent, of the children showed either no reaction or a very faint one. The faintest reactions detected were classed as +.

Tabulated results are as follows :—

Those receiving three i

injections-

Absentees, Objectors, &c.

+

rb

4-

304

176

53

Nil ..

.. 46

Those receiving two injections—

+

db

+

30

Totals—

12

6

Nil ..

.. 15

-f*

zb

4

1

334

188

59

Nil ..

.. 61

To get the full significance of these figures, it is necessary to hark back to the original tests, which comprise a series of 1,581 children, including 88 who had been previously tested and partially immunized.

Their reactions were recorded as

follows :—

4- .. ..

390 ..

24 '74 per cent.

± .. ..

177 ..

1119 „

158 ..

9 -99 „

Total positive ..

725 ..

45 92 „

Negative ..

856 ..

54 08 „

Of this total 144 were lost through absence, objection, &c., in the course of the procedure.

The reactions of the remaining 1,437, two months after the course of injections, reads as follows :—

4- ..

.. Nil ..

Nil

it * •

.. 59 ..

4 T per cent,

+ , #

GO

GO

r—1

13 1 „

Total positive

.. 247 ..

17 2 „

Negative

.. 1,190 ..

82 *8 „

This table shows that 82 8 per cent, of the 1,437 children on whom the full course of procedure was carried out are presumably now immune from diph-thcri . This figure represents over 25 per cent, of the school children of Bendigo and Eaglehawk.

A graph (No. V.) has been prepared comparing the results recently obtained v th the original test in 1,493 children.

Regarding the reactions classed as +, many o them were exceedingly faint, and it is thought probable that if tested at the end of a further four months, the great ma oritv both of that grade and also of the higher grade would yield negative results.

In that aspect, the index of immunity obtained would approach those obtained by American observers.

The following table shows the alterations in reactions following the injections :—

Table 14.—Alterations in Schick Reactions following

Immunizing Injections.

Reactions.

Receiving three injections.

Keeeiving two injections.

+to ±........

40

4

4- to + .. .. .. ..

129

7

4- to — .. .. .. ..

127

16

no change .. .. ..

13

2

4~ to 4~ ». .. .. ..

35

1

db t° — • • .. .. ..

81

6

+ no change .. .. ..

12

4

Hh to — .. .. .. ..

96

8

Totals .. .. ..

533

48

Graph V. Reduction in Number of Schick-PosiNvr' Two Months afrer Giving Immunizing Injections.

Negative.


53 05 %


1.    Read ions of 1483 Children Not Previously Tested.

2.    Reactions of 1437 Children (including 6d previously tested and partially immunized) Two Months after

Course oP Toxin-Antitoxin Injections Hod Been Administered to Positive Reactors.

NOTE: This senes indudes 46 children tv/io received only 2. instead oT 3 injections; but; necessarily, does not include the Reactions oP 144 children who, through absence, $c, received one or no injections.

An inspection of this table reveals the fact that, out of 533 children receiving the full course, only 25, or 4 *7 per cent., failed to show a reduction in the strength of reaction. Also, out of 48 children who only received two injections, all but six or 12 5 per cent., showed a noticeable diminution of reaction.

Age-incidence of Reactions after Immunizing Injections.

The table of age-incidence of reactions after attempted immunization is given as follows :—

Table 15.—Age and Sex Incidence of Reactions after Immunizing

Injections.

No. of

Grade of Reaction.

Acre.

Injec

tions.

Under

4.

**.

5.

6.

1,

8.

9.

10.

11.

12.

13.

14.

Over

14.

Not

Stated

Total.

3

. _

1

1

15

24

26

27

48

30

50

35

28

6

9

4

304

± • * • •

. .

3

14

21

19

28

24

16

16

15

12

3

2

3

176

i " ‘ *

1

1

2

8

11

7

7

5

6

3

1

• •

• •

1

53

Total ..

2

5

31

53

56

62

79

51

72

53

41

9

11

8

533

2

— .. ..

1

4 #

m #

4

o

3

9

4

3

1

1

1

1

30

+ .. ..

• •

1

3

2

1

2

• •

9

, •

..

1

• .

• •

• *

12

±-- ••

2

• •

9

• •

1

• •

• •

1

• •

• •

• •

6

Total ..

1

1

3

8

/

7

9

7

3

1

O

o

1

1

*• •

48

Grand totals

3

0

34

61

59

69

88

58

75

54

44

10

12

8

581

The percentage of reactions for each year of age has been plotted on Graph VI., and shows an interesting contrast to the curves on Graph III.

The full positive ( + ) curve is absent, and its place is taken by the mildest form of reaction (+).

The d: curve comes to zero at fourteen years, and shows a low percentage throughout.

The high percentage of reactions up to the age of four, and the absence of drop in the curve which continues up to the age of eight years, indicate that the older children are more readily immunized than the younger ones.

One feature of this series of tests which is worthy of emphasis is the large number of reactions which, although graded as +, consisted actually of nothing more than a slight local blush visible at the first inspection, occasionally attended by very faint pigmentation at the period of the second inspection. As, in these cases, the control showed no sign beyond the needle-track, these residual reactions were classed as positives (+), and are taken to indicate the least possible degree of susceptibility, and, largely on account of the number of these observed, one estimates that if a further test were performed in four months’ time, the bulk of those children classed as positive would fail to react.

Graph VI. Percentage of Children at Each Year of Age Remaining Schick Positive after Three Immunizing Injections.

V— REVIEW OF THE CAMPAIGN IN 1923.

That this campaign has justified its inception and undertaking from the point of view of actual results is already being evidenced. As previously stated, t he Bendigo Hospital diphtheria ward remained empty for the last three weeks of the month of August, practically the only time in the history of the hospital that it has been empty.

Also during that month no cases of diphtheria were notified in the municipalities of Bendigo and Eaglehawk, an event which has not occurred since September, 1917.

These facts are undoubtedly due, in large measure, to the isolation and treatment of carriers in the campaigns of 1922 and 1923, whatever other factors may have contributed in the way of low State incidence, &c. At the same time, some measure of credit must be given to the testing and immunization of nearly 30 per cent, of school children susceptible to the disease.

Details have been obtained from all cases of diphtheria in Bendigo since the commencement of the immunizing process, and, with one exception, no child receiving the full course of treatment has contracted the disease. This case occurred within ten days of receiving the final injection, and, consequently, immunity could not have been expected to have developed. The case was mild and uncomplicated.

One case has already been discussed of a suspicious throat occurring in a Schick-negative. No other cases have occurred in children tested and found Schick-negative.

An interesting incident occurred in a family of four children, all of whom were Schick-positive.

Two of these children had received the full course of treatment, one had received two injections, and the fourth only one.

The child who had received two injections contracted a mild diphtheria and was taken to hospital. Two days later the brother who had only one followed him with a mild attack. The other two children escaped infection.

It is probable that the two children who escaped and who must have been subjected to the same mass of infection in their home, would have contracted the disease had they not received the full immunizing dose.

In another family of two girls, one was found to be Schick-positive and one Schick-negative. The former was unable, through sickness, to attend school to receive the immunizing injections, and later contracted a mild diphtheria. The other escaped with a mild sore throat, without fever or malaise, although a swab-culture revealed the presence of K.L.B.

The cases have already been mentioned of two Schick-positive children who were found to be carriers of virulent bacilli. These cases are of added interest, in view of the Medical Research Council's recent publication, No. 75 (The Schick Test), in which Surgeon-Commander S. F. Dudley, R.N., states that no case, of a Schick-positive carrier of virulent bacilli had come under his notice.

Both these cases received the full immunizing course, and failed to react two months later.

it is interesting, also, to note that in one ease the throat and nose were normal, while in the other a slight enlargement of the tonsils only was noted.

Two outstanding points in connexion with the swabbing section of the campaign are—firstly, the very high percentage of teachers who were found to be carriers ; and, secondly, the extremely high percentage of carriers who were found to be suffering from nose and throat complaints.

In connexion with the first point, special advice to teachers in matters of nasal and oral hygiene would be attended with advantage.

The second point concerning nose and throat defects in school children brings more vividly before the public eye the necessity for the treatment ui diseased tonsils, adenoids, &c.

There can be no doubt that the effect of instructing carriers to douche and gargle regularly has had beneficial results, apart from the immediate effect ot clearing up the carrier condition in improving the health of the air-passages.

The virulence testing has provided very useful information, more particularly in connexion with the technique of the test itself. The knowledge gained in the combating of ** masking infections " in the animal subjects will prove4 of great value in future tests.

The Schick test and trial of active immunity met with an excellent response on the part of the parents, and it is expected that the full benefits of this section of the work will manifest themselves from this time onwards.

It is thought likely that if this programme is repeated in following years an even larger percentage of children will be submitted, and that ultimately even practically the whole of the children of the district will be immunized against diphtheria. The dread of this complaint is in every home in this part ol the State, on account of past experience, and the good results secured this year should have a marked effect in inducing the doubtful in the future.

This work could, with advantage, be commenced in other parts of the Commonwealth where diphtheria is prevalent. By this means, particularly, the incidence of diphtheria in Australia could be reduced to a minimum.

The work of the campaign in the Commonwealth Health Laboratory was completed on 28th August with the final inspection of the last Schick test .

In all about 12,(XX) swabs were examined and upwards of 200 virulence tests performed. The Schick test and active immunization process entailed t ho administration of between 6,000 and 7,000 inoculations and the paying of over 250 visits to various schools in a radius of about 4 miles.

Although the campaign arose under the aegis of the municipalities, their original programme was greatly expanded by the Commonwealth Department of Health.

Apart from the actual taking of the swabs, practically the whole of the work was done by the Health Department officers.

Thanks are due to the mayors of Bendigo and Eaglehawk for the active interest and help given to the progress of the Schick test, and are also due to the various municipal councils, as well as to the health officers, of each municipality.

Especially valuable assistance was rendered by Mr. J. E. Paynt-er, Health Inspector for Bendigo, and by Sister Turnbull, the Municipal Nurse, for the efficient manner in which the swabs were taken and delivered daily to the laboratory, and in which records were kept.

I am personally indebted to Mr. Paynter for his kindness on various occasions and help in the matter of transport to the more outlying schools. Without that it would have been an exceedingly difficult matter to have visited them all on scheduled time.

I also wish to extend thanks to Dr. J. S. Greig, School Medical Officer of Victoria, and to Dr. K. C. Purnell, Medical Officer of Health for Geelong, for their kindness in supplying me with records, and to Dr. J. C. Ross, Medical Superintendent of the Bendigo Hospital, for keeping me in touch with the few cases of diphtheria that arose this winter.

VI.—SCHICK TEST AND ACTIVE IMMUNIZATION PROCESS, 1921.

Procedure and Methods Adopted.

The campaign against diphtheria for 1924 in Bendigo and district was limited, for various reasons, to the use of the Schick test and active immunization process.

An early start in the school year was made, and the preliminary publicity campaign in the newspapers and among schoolmasters was repeated.

Kind assistance was rendered by the Colonial Mutual Life Assurance Society, whose publicity officer, Mr. W. Wallace Woodland, visited me and prepared a pamphlet for distribution among the school children, as well as the policy-holders of the society. Unfortunately this pamphlet was evolved a week or two late, and was not available for distribution sufficiently early to have had its full effect.

The same method of obtaining consent of parents was used as that previously described (1923). It is thought that, had the Colonial Mutual pamphlet been available earlier, the returns would have been largely increased.

In all the consents of 969 fresh children were obtained, as compared with 1,616 for the previous year.

The same method was used in preparing the toxin for the test and control, and the same technique adopted in performing the tests, with the exception that the tests were performed single-handed throughout.

A variation of procedure was introduced in reading the results. On account of the fact that I was single-handed, it was thought reasonable, instead of taking readings on the fourth and tenth days, to take oijy one reading, and that on the eighth day. By that time practically all false reactions have subsided, while true positive reactions are still easily readable ; in addition, the formation of a weekly time-table, thereby made possible, entailed the saving of two or three weeks of visits.

In one case, it appears, this time-saving was responsible for an incorrect reading. This case was classed as giving a pseudo-negative reaction in seven

days, and subsequently developed diphtheria. There is no doubt in mv mind that the pseudo-reaction masked a positive Schick reaction, which was overlooked. This is the only case, hitherto, of a child classed ¿is Schick-negative subsequently developing diphtheria in the two years5 series, totalling nearly 2,600 cases.

Its occurrence emphasizes the need for careful examination of all false reactions, and it is thought wise to re-examine all such a week later, if the seven-day reading is used.

The same method of grading results arbitrarily into +, -±, and +, according to severity of reaction, was used.

Table 15.—Showing Results of Schick Tests by Schools, 1924.

No.

School.

Age

Aver

age.

Xo.

Ab

sents.

Xo. of Positive.

Nega

tive.

Percen

tage.

+ .

P»eudo-rea elione.

+ .

-i-.

+ .

Total.

+ .

Total.

Perce n-tage.

I

Central ..

9*1

140

2

35

30

22

87

51

62-2

7

t

5 *0

2

Quarry Hill ..

7*9

63

1

15

12

4

31

31

50-0

4

4

6-8

3

Domestic Art ..

13-1

15

. ,

1

2

3

6

9

40-0

l

l

6-6

4

St. Joseph’s ..

7-7

18

. ,

2

6

3

11

7

61-1

1

1

5*5

5

St. Killian’s ..

7*7

44

è #

9

5

2

16

28

36*3

2

2

4*5

6

Marist Brothers ..

11-3

11

1

1

2

9

18*1

1

1

9 0

7

Gravel Hill ..

7-7

109

2

30

23

15

68

39

63-1

2

5

7

6*5

8

Long Gully ..

7-3

29

1

2

5

5

12

16

42-8

9

Specimen Hill ..

8-9

7

..

7

1

1

14*3

10

Violet-street ..

8-0

122

1

21

14

15

50

71

41-3

3

8

1L

9*9

11

Rae’s Hill ..

11*8

23

3

1

3

7

16

30-4

3

3

13*0

12

Technical ..

12-5

9

1

2

3

6

33-3

1

1

2

22*2

13

High .. ..

14-0

27

1

1

3

5

22

18*6

2

2

6*6

14

Convent ..

8-7

13

• •

, ,

, .

# ^

13

..

2

2

15*4

15

North Bendigo ..

8-0

81

8

11

16

35

46

43-2

2

5

7

8*6

10

East Bendigo ..

7-0

13

1

2

1

4

9

30*7

1

1

7*6

17

White Hills K.C.

7-1

7

1

1

2

4

3

57-1

18

White Hills S.S.

7*1

7

1

3

4

3

57-1

19

Girt on ..

11*3

20

2

i

3

12

8

60*0

1

1

5*0

20

Golden Square ..

8-6

41

8

6

6

20

21

48-7

2

2

4*8

21

Eaglehawk North

0*7

4

..

1

• •

1

3

25-0

22

St. Li bonus’ ..

8-2

4

s .

2

l

3

1

75-0

23

Eaglehawk Central

8-4

120

16

22

21

59

61

49 * 1

1

6

7

5*8

24

California Gully..

8-0

36

7

1

4

12

24

33*3

1

5

6

16*6

25

Unattached ..

5-5

6

1

• •

1

1

2

3

40-0

Totals (average)

8*09

969

8

164

159

131

454

507

47-2

11

57

68

7*1

Statistics.

In the 1924 series of 969 tests eight were not completed through absence of the child from school. In the remaining 961, positive reactions were recorded as follows :—

4-    ..    ..    164

±    ..    ..    159

+    ..    ..    131

454

507


Negative

The percentage of total positive reactions, therefore, was 47 2, as against 46 '96 per cent, in previously untested children in 1923.

Age axd Sex Incidence.

As will he seen from Table 16, the age-incidence curve bears a verv similar aspect to that obtained in 1923 (Graph No. III.).

rn

l ABLE

16.—,

Vue

AND

Sex

Inc

IDEXCE

of Schick Re

ACTIONS

, 1924.

Age.

Heiv-t i<*n.

Sex.

I'wler

4.

1

4.

1 .

6.

7.

X.

0.

10.

11.

12.

13.

14.

Over!..,,. , 14. l"tnI

■Craml ‘ Totals.

!

-T • •

M.

5

10

20

10

•_>

»

4

8

7

1

. . 74

>HU

± ••

F.

♦ ,

2

16

21

8

10

7

12

7

4

2

1

.. 90

M.

. .

5

15

12

1 1

12

6

0

5

5

2

2

.. 81

} 159

F.

• •

2

13

10

10

9

10

9

0

3

4

l

1 78

T . .

*M.

F.

l

I

11

6

13

4

3

13

8

6

7

8

3

7

7

5

0

8

3

7

1

1

l 04 l 07

}>*

Total positive

• •

1

15

71

80

55

47

45

41

38

33

18

7

3 ••

454

Negative ..

M.

m 0

6

27

30

32

30

33

35

34

25

15

4

3 274

F.

1

1

18

22

29

23

20

23

28

17

21

13

11 233

Total negative

1

7

45

52

01

53

59

58

02

42

36

17

14 ..

507

totals . .

2

22

110

132

110

100

104

99

100

75 |

54

24

17 ..

901

Percentages

..

50

ox -1

01 -2

00*1

47 • 0

47*0

43-2

41 -4

38-0

44-033*3

29-117-0 ..

47-2

Of 493 males 219. or 44 6 per cent., were positive, while of 468 females 235, or 48 1 per cent., were positive. These figures bear a remarkable similarity to those obtained for the two sexes in 1923, viz., 44 6 per cent, and 19 *6 per cent, respectively.

Previous History of Diphtheria.

Of 127 children who had had one previous attack of diphtheria 50 were Schick-positive and 77 Schick-negative ; percentage positive, 39 '2.

Of three children who had had two previous attacks one was Schick-positive and two were Schick-negative ; percentage positive, 33 *3.

Of two children who had had three previous attacks both were Schicknegative ; percentage positive, nil.

Altogether, of 127 children with a history of previous diphtheria, 51, or 38 '6 per cent., showed a positive reaction and 77 a negative. These figures show a slight variation from those obtained in 1923, when 43 per cent, of children with a previous history of having had diphtheria were found to be Schick-positive. Both results show that, while very slight, an attack of diphtheria apparently confers some immunity of a lasting nature. The average age of the above series of children was 9 '9 years ; a corresponding point on the Graph A shows about 45 per cent, among normal children.

Pseudo-reactions.

These reactions were observed in 68 cases, equalling 7 1 per cent., as against 10 per cent, in 1923. This latter figure, however, was high, and was accounted for by the fact that 26 *1 per cent, of children who had been tested and partially immunized in 1922 showed pseudo-reactions in 1923. The remainder of the children tested showed only 9 per cent, of false reactions.

In the present series eleven masked positive reactions and the remaining 57 were classed as pseudo-negative, although, as previously noted, in one instance a child subsequently developed diphtheria. In this instance, almost undoubtedly, his pseudo-reaction masked a positive Schick reaction.

The age-incidence curve of pseudo-reactions is similar to the 1923 curve, and emphasizes the fact that false reactions are not likely to occur in the younger children, the great majority occurring at ten years and thereafter.

Table 17.—Age-incidence Table of Pseudo-reactions.

A«e.

Under

4.

4.

5.

t

8.

o.

10.

11.

12.

13.

14.

Over

14.

Totnl.

Masking Schick-positive .. ..

1

1

1

1

1

2

I

1

3

11

Pseudo-negative ..

• •

• •

1

6

3

7

3

12

10

9

4

1

I

57

Totals ..

• •

• •

2

7

4

7

4

14

11

10

7

1

1

68

Percentage at each age ..

• •

• •

1-7

5*3

3*4

7-0

3-8

14-1

10-0

13*3

12-9

4*1

5*9

7*1

AcTIVE IMMUN1ZATIO N.

This was carried out as on the previous occasion ; three injections of, respectively, J- c.c., \ c.c., and 1 c.c. being given at intervals of one week.

Of 454 Schick-positive children, 29 were either absent on the occasions of all injections or objected formally to the continuance of the treatment.

Of the remaining 425—

22 received one injection only,

29 received two out of three injections, and 374 received the full course of three injections.

Reactions.

No serious reactions were observed following the immunizing injection.

Testing of Immunity.

In 1924 a period of four months was allowed to elapse between the final immunizing dose and the retesting. This, it was hoped, would show a bigger percentage of immunized children than the two months' interval allowed in 1923, as immunity is stated to develop throughout six months.

The tests were performed as before, and one reading taken on the eighth day.

Of 374 children receiving the full course of three injections—

48 were absent or objected ;

314, or 96 3 per cent., of the remainder showed a negative reaction ; and

11,    or 3 3 per cent., showed a very faint + reaction ; while 1 only showed a —, or second-grade reaction.

This single case will be referred to later.

Of 29 children who received two injections only—

15 were absent or objected ;

12,    or 85 *7 per cent., of the remainder showed a negative reaction ;

1 only showed a faint + reaction ; and

l only showed a or second-grade reaction.

This case will also be referred to later.

No full positive -+■ reactions were observed.

The following table serves to show the percentages of immunes after two and four months’ intervals respectively :—

Before Immunizing.

Receiving three Injections (full course).

Gra8e of Reaction.

1923.

1924.

After t/ro months, 1923.

After four mont hs, 1924.

4~

O '

/o

24*7

o

/o

170

Of /o

Nil

o

A)

Nil

d:

11-2

10*4

4*1

0*25

-e

100

13*8

13*1

1*40

54-1

52*8

82*8

98*35

This table shows clearly that the index of immunity is considerably higher at the end of four months than it is after two months’ development, and supports the claims of American investigators.

Table 18.—Age Incidence Reactions after Immunizing

Injections.

No. of Injections.

Grade

of

Reaction.

Vse.

Under

4.

4.

6.

0.

7.

8.

9.

10.

11.

12.

13.

14.

Over

14.

Totals

2

+ ..

1

1

+ . .

, ,

1

• »

• •

• .

• .

..

. .

. .

. .

..

1

• •

3

2

• •

3

• •

2

1

• •

1

12

Total

* •

V

3

3

• •

3

2

2

• •

1

14

3

4* ..

1

..

1

+ ••

1

2

2

1

1

2

1

1

• .

• ,

11

• •

7

45

57

30

30

33

29

33

19

12

5

2

314

Total ..

• •

7

40

59

38

37

34

32

33

20

13

5

2

320

As reactions of any grade were so rare in the retesting during 1924, a graph would not show any accurate curve.

Discussion of Results.

A point of interest in the reading of these tests was the occurrence of the two -U reactions, the only reactions of moderate strength observed in this particular series.

Both these cases were unfortunate enough to contract diphtheria during the year before immunity was well established, although in each case the attack was mild.

The first instance, a girl aged ten, received the full course of immunizing injections, but contracted diphtheria within a month of the final dose, at a period when immunity is not accepted as being well established. She recovered without complications, and her Schick reaction, when observed four months after the immunizing injections, was found to be, if anything, more markedly positive than before attempted immunization.

A second child, a boy of eleven years, also contracted diphtheria in a very mild form within a month of his final immunizing injections ; but, unfortunately, his parents would not permit the final test to be performed on him.

The other case mentioned was that of a girl of thirteen years, who contracted diphtheria within two or three days of receiving the second immunizing dose, and who, consequently, did not receive the final dose.

In her case the second test showed a much more severe reaction than the first. In neither of those cases was a pseudo-reaction observed at the final test.

Summary.    .

The testing and immunization of 960 children during the year 1921 added to the total of 1,616 during 1923, make a total representing well over 40 per cent, of the total school children of Bendigo and Eaglehawk.

Certain cases of diphtheria have occurred among this series ; but in almost every instance the child in question has failed to receive complete treatment, being absent from school on one or all occasions of reading tests or immunizing.

Three exceptions are noted. Two of them are comprised by the two cases just quoted, who received three immunizing injections, but contracted diphtheria within a month of the last. It is not claimed that a practical immunity is established until at least two months after the final dose.

The third case has, also, already been mentioned as occuring in a boy whose Schick reaction was read as pseudo-negative. There is no doubt that this was an error in reading on my part, and that the protein reaction in reality masked a positive Schick reaction.

Apart from these cases, no case pronounced immune, naturally or artificially, has contracted diphtheria up to the time of writing.

During 1923 87 cases of clinical diphtheria were notified in Bendigo, and during 1924 91 cases. These figures show a great improven ent on the totals for 1920-21-22 (350, 469, and 189 respectively).

The year 1923 was a light year for diphtheria throughout Victoria, only 3,407 cases being notified, as against 9,458 in 1921 and 5,323 in 1922. The incidence in 1924 was somewhat heavier in Victoria generally than in 1923, 3,987 cases being reported. The Bendigo annual total of cases showed a very slight increase only.

Taking the total of children tested and immunized during 1923 in Bendigo, as representing 25 per cent, of the total children of the district, one would expect, in the absence of artificial immunization, to find about 20 cases occurring among those children during 1924, whereas not one case has yet occurred in a child pronounced immune in that series. Thus the value of the Schick test and Active Immunization process is already being evidenced in this district.

VJ1.—REVIEW OF THE CAMPAIGN, 1923-1924.

The work recorded in these reports is that of a campaign against diphtheria carried out amongst the school children in Bendigo, and the Borough of Eagle-hawk, as well as the Shires of Marong, Strathfieldsaye, and Huntley during the years 1923-1924. The area is in the centre of a prosperous mining, industrial, and agricultural district, situated some MX) miles by rail from Melbourne. The census population (1921) of the area covered by the campaign was 42,763. Attention had been called to the high diphtheria incidence in this community, and a swabbing campaign carried out in 1922 by Dr. Featonby, of the State Commission of Public Health, had resulted in an apparent reduction in the incidence of diphtheria. The work here recorded covers a swabbing campaign, combined with the use of the virulence test, and a campaign in which the Schick test and active immunization were adopted. The work performed has been fully recorded in the reports, both as regards procedure, technique, and the results obtained. Every opportunity was taken to utilize the facilities provided, in order to gain technical experience in the furtherance of the work, and attention is particularly called to the work of Technical Assistant Grant in regard to the protection of guinea-pigs used in the virulence test against infection by interfering organisms.

In regard to the results of the work, the effect of the swabbing incidence on the local incidence of diphtheria has been fully reviewed (page 61-2). The consideration of the end-results of the Schick test and active immunization deals with two aspects, (a) that of the individual and (b) that of the community.

(a) The results as affecting the individual might be considered in terms of the incidence of diphtheria among immunized persons, and of instances of cases occurring in families where immunized persons lived.

(i) Incidence of Diphtheria among Immunized Persons.

Only three cases have been observed of children who have received the full course of three immunizing injections developing diphtheria at a period of more than two months after immunization was commenced.

In two of these cases, the final Schick test after immunization showed a mild grade of positive reaction. This is taken to indicate that a further

immunizing course would have been beneficial, and would, in all probability, have prevented the occurrence of the attack.

The first case was a boy, aged twelve, whose arm showed a second-grade reaction four months after the final immunizing dose, and who developed diphtheria less than six months later.

The second case was a girl of five, who showed a very mild reaction two months after treatment (1923), and developed diphtheria about eight months later.

The third case was a girl of fifteen, whose reaction was recorded as negative two months after treatment in 1923, and who developed diphtheria eighteen months later.

Two cases are recorded of children contracting diphtheria within two months of receiving the full immunizing course of three injections, at a period when it is not claimed that a practical amount of immunity has developed.

One case only has been observed of a child who was classed as Schicknegative, and hence, naturally immune, subsequently developing diphtheria.

In this case a psuedo-reaction was recorded, and it is considered beyond doubt that this reaction in reality masked a faint positive reaction, and that the reading of pseudo-negative was an error.

(ii) Instances of Cases occurring in Families where Immunized

Persons Lived.

In five instances cases of diphtheria have been noted as occurring in families containing immunized children.

In two of these cases the subject was an infant under two years of age, and all other members of the family escaped infection.

In another case, in a family of four children, the youngest, who had been neither tested nor immunized, contracted diphtheria, while the other three immunized children all escaped infection.

In a fourth instance, occurring in a family ol four children, all proved Schick-positive ; one incompletely immunized child (one injection only) contracted diphtheria, and infected a second incompletely immunized member of the family (two injections only). The other two children who had had the full immunizing course escaped infection.

The fifth instance occurred in a family of three boys. One was classed as Schick-negative, the other two being Schick-positive ; one receiving tin; full course of injections and the other two only. The last-mentioned boy subsequently contracted diphtheria, but the other two were not infected.

(h) The results as affecting the comm unity.—The interpretation at present of the effect of such a campaign on the incidence of diphtheria in the community is difficult, in view of the natural annual fluctuations known to occur in diphtheria prevalence. Even comparison with another community, similar in regard to geographical situation and population, presents certain difficulties.

In comparing the incidence of diphtheria in various localities in Victoria over the past five years, the following figures have been compiled by the State Commission of Public Health : —

Table 19.—Cases of Diphtheria Notified in Different Areas in

Victoria.

Reported Cases of Diphtheria.

Annual Cases per 10,000 of Population.

19*20.

1921.

19*22.

1923.

1924.

1920.

1921.

1922.

1923.

1924.

Greater Melbourne

2,G98

3,724

2,213

1,900

2,239

35-8

47'3

27-5

22.8

25-7

Ballarat and suburbs

330

307

111

90

54

83'0

79'7

28-2

22-5

13-3

Bendigo and suburbs

428

521

215

91

111

124-0

157'1

64-3

27'2

33-0

Geelong and suburbs

369

405

200

98

127

107-0

112-0

54-9

26'4

33'6

Rest of the State ..

2,633

4,501

2,584

1,288

1,456

411

71-6

39-4

19-4

22-0

Total State ..

6,458

9,458

5,323

3,467

3,987

42-7

61-5

33-9

19-5

24-3

More detailed information is available from a return furnished by the courtesy of the Town Clerk of Ballarat, and since Ballarat presents many features in common with Bendigo, the following tables are recorded, showing the incidence recorded in Ballarat (population 37,000) and in Bendigo (population 26,000) :—

Table 20.—Cases of Diphtheria Notified per 1,000 Population.

Year.

Bendigo.

Ballarat.

1920 .. .. ..

13*46

3-40

1921 .. .. ..

18*04

4-16

1922 .. .. ..

7*27

2*0

1923 .. .. ..

3-38

2*0

1924 .. .. ..

3*50

1-48

Table 21.—Cases of Diphtheria Notified per 1,000 School Children.

Yea r.

Bendigo.

Ballarat.

1920 .. .. ..

41-6

Not available

1921 .. .. ..

57-6

12-0

1922 .. .. ..

21-4

5*35

1923 .. .. ..

6-6

4-08

1924 .. .. ..

9-8

2*0

♦ In tlu; case of Bendigo actual notifications of children attending school are given. In the case of Ballarat, children hetwoen the ages of "»-Li years, inclusive, have been taken as school children.

Table 22.—(a) Age and Sex Incidence of Cases Notified in Bendigo

and Ballarat, 1923-1924.

Year* ot Ace.

City.

Year.

Sex.

Under

5.

5.

-

6.

i

8.

0.

10.

11.

12.

13.

Over

13.

Not

Stated.

All

Aces.

Bendigo

1923

M.

7

i

4

4

0

1

4

o

&

1

14

40

F.

7

. .

2

4

3

1

1

1

0

1

3

22

47

Total ..

• •

• •

14

3

8

7

r '

3

2

5

4

1

4

36

87

Bendigo

1924

M.

4

3

2

3

2

1

2

4

3

1

i

. .

32

F.

8

4

8

5

4

2

3

3

2

2

18

• •

59

Total ..

• •

..

12

7

10

8

6

3

5

/

5 3

25

91

Ballarat

1923

M.

5

1

3

1

1

12

23

F.

11

3

3

1

4

3

3

1

• •

2

19

• •

50

Total ..

16

4

3

4

4

3

3

2

i

2

31

• •

73

Ballarat

1924

M.

3

2

1

1

2

1

7

..

17

F.

9

2

2

• •

2

• •

1

' *

• •

11

1

28

Total ..

• •

• •

12

4

3

1

4

• •

2

18

1

45

Table 22.—(6) Summary Age Incidence.

City.

Year.

Under 5.

5-13.

Over 13.

Total All Ages.

Bendigo

1923

14

37

36

87

1924

12

54

25

91

Ballarat

# %

..

1923

16

26

31

73

1924

12

14

18

44

(1 unspecified)

Table 23.—Seasonal Distribution of Diphtheria Cases Notified by

Months, Bendigo and Ballarat.

City.

Year.

Jan.

Feb.

Mar.

A pr.

May.

June.

July.

Aug.

Sept-

Oct.

Nov.

Dec.

Total.

Bendigo ..

1920

7

18

71

58

48

29

37

16

22

21

6

17

350

1921

8

10

48

67

133

77

39

26

19

12

11

20

469

1922

16

24

53

43

18

17

13

6

5

1

1

1

189

1923

3

4

10

10

16

13

10

4

10

6

1

87

1924

• •

2

14

15

11

8

12

7

6

5

6

9

91

Ballarat ..

1920

2

5

17

5

28

19

11

11

12

6

5

5

126

1921

7

16

24

43

29

11

5

4

2

7

3

3

154

1922

4

8

7

7

5

7

9

7

9

2

7

1

73

1923

5

5

19

5

10

6

9

6

3

1

3

1

73

1924

1

3

7

9

8

8

4

» •

5

• •

• •

• •

45

Consideration of these tables indicate that the history of diphtheria in Victoria during the past five years has shown a high and widespread prevalence in 1921, and since that year a declining incidence with a slight rise in 1924. Ballarat, whilst sharing in the prevalence, has consistently shown a lower incidence than Bendigo, and the incidence continued to decline in 1924. whilst Bendigo showed a slight rise in incidence corresponding with, although slightly less than, the general rise throughout the State. This rise in incidence in Bendigo was almost wholly made up by an increased number of eases amongst girls of school age (Table 22a). The indication is given that Bendigo has shown a proportionately greater decline than Ballarat and other parts of the State, although the data are such that the results cannot be considered wholly significant in terms of a comparative reduction in incidence. On the other hand, considering the expectation and actual incidence in the immunized school population (40 per cent, of the total school children), the evidence given justifies the deduction that the campaign was successful in protecting that 40 per cent, of the school children against the possibility of infection,

although it has not resulted in a gross reduction in diphtheria prevalence throughout the community.

Conclusions.

Although it may be claimed that the work of the campaign has reduced the local incidence of diphtheria to a point below the prevalence of preceding years, yet deliberate attention must be given to the fact that, in spite of the expenditure of much time and energy over three years, a residual prevalence of diphtheria remains at a level actually higher than that of Ballarat. Possibly this may be because the campaign did not effectively reach the 2 5 year age group—the pre-school population amongst whom diphtheria reaches a high incidence—or because the Schick testing and active immunization reached only 40 per cent, of the total school population (or 25 per cent, of the total child population of the district). The active immunization campaign as a community, as distinct from an individual or institutional measure must obviously reach both the pre-school population and the total residual school population, a range of administrative activity which may well require serious consideration, rndoubtedly time and administrative procedure can be saved by discarding the test and immunizing all children, or by the recent development in utilizing the first immunizing injection as the test. Even then the procedure necessitates the continuance of the campaign as a routine for the total child population of the community.

In reviewing the work that has been done in Bendigo during the three years, 1922 1924, it is difficult at this stage to assess the comparative values of the swabbing campaign and the active immunization by injection of the toxinantitoxin mixture. The results of the work throughout are suggestive; but valuable as this extensive piece of work may have been, it shows clearly that the Schick testing and toxin-antitoxin immunization does not provide a dramatic

or abruptly conclusive solution for the diphtheria problem. Granting the already confirmed value of active immunization as an individual and an institutional procedure, there is much to suggest that the established methods based upon reliable notification of cases and activities indicated by the circumstances of the actual known case of diphtheria, cannot vet be discarded or modified in any detail. Such methods postulate a procedure involving the following up of every case and the careful swabbing of every contact or possible contact, combined with a perfecting of early diagnosis and segregation, and the education of parents and general practitioners in dealing with all cases of slight throat ailments.

By Authority : H. J. Green, Government Printer, Melbourne.