Lowered vaccine dose for immunisation of calves against tropical theileriosis using Theileria annulata lymphoblasts.

Bovine tropical theileriosis is of high incidence in calves below 2 months old in India. The Theileria cell culture vaccine evolved by the Punjab Agricultural University (PAU) was evaluated previously for its efficiency and safety in younger calves, both experimentally and in the field. The dose of cells used for vaccination was regulated at 1.75 to 2 x 10(6) cells. This study, which was undertaken to assess the minimum number of cells which would be effective and safer for vaccination, showed that optimal protection was given by a dose of 1 x 10(6) cells.