Rates of common communicable illnesses in non-anaemic 12-24 month old South Island, New Zealand children

Aims : To describe the incidence of parentally reported illness in otherwise healthy South Island toddlers; characterise the predictors of illness; and determine whether there was a relationship between teething and illness in this population.

Methods : A 20-week randomised controlled trial was conducted on 1-year-old children (n=225) from Otago and Southland between February 2004 and December 2005. Information on symptoms of morbidity, occurrence of teething, and childcare attendance were recorded daily throughout the intervention period. Morbidity symptoms were categorised into respiratory illness (RI), gastrointestinal illness (GII), ear infection, and total illness, and the number and duration of events were determined.

Results : The mean (SD) number of total illnesses was 3.4 (2.3) per 20 weeks, with an average duration of 4.5 days. Episodes of RI were most common (50% of total illness events), and tended to be the longest in duration (mean of 3.7 days). Having siblings aged less than 5 years (23% increase, 95%CI 6%–42%, p=0.007) and attending childcare (72% increase, 95%CI 38%–113%, p<0.001)), were positively associated with the number of total illness events but not duration. In addition, teething was positively associated with total events (OR 1.94, 95%CI 1.45–2.60, p<0.001), RI events (OR 2.03, 95%CI 1.41–2.93, p<0.001) and GII events (OR 1.90, 95%CI 1.36–2.67, p<0.001).

Conclusion : This study has shown that illness (particularly RI) is common in the second year of life. It has also confirmed that attending childcare and having siblings aged under 5 years increases the number of illness events. An association between teething and the occurrence of illness was also seen but the exact nature of this relationship requires verification.