Decrease in erythrocyte survival in Theileria sergenti-infected calves determined by non-radioactive chromium labelling method.

Pathogenesis of anemia in the calves infected with Theileria sergenti was investigated from the viewpoint of erythrocyte survival decrease in the circulating blood. For investigation of erythrocyte survival a method of erythrocyte labelling with non-radioactive chromium (50Cr) was utilized. It was found that (1) the erythrocyte survival decreased markedly in the T. sergenti-infected calves compared with that in the uninfected calves; the survival rate of 25.7% for infected calves and 86.0% for uninfected ones on the fourth day after re-introduction of the labelled erythrocytes into the original donors, and that (2) the survival of non-parasitized erythrocytes in the infected calves was also decreased, which indicates no obvious relationship between parasitism and decrease in survival of erythrocytes.