The quantitation of Trypanosoma congolense in calves. 1. Hematological changes.

Anemia due to Trypanosoma congolense infection in neonatal and 6-month-old calves was hemolytic and moderately responsive. The red cells were macrocytic and normochromic in both groups of calves and the anemia was milder in infected neonatal calves compared to the 6-month-old calves. The neonatal calves maintained normal white blood cell counts and developed a lymphocytosis at two weeks of infection. The six-month-old calves developed mild neutropenic leukopenia at one week post-infection without lymphocytosis. Plasma iron turnover rates were not different between infected and control calves in either age group at the second week of infection but both groups of infected calves had higher turnover rates at the sixth week of infection. The mean percent of radioiron uptake into peripheral blood red cells was similar in the controls and infected calves, but the rate of appearance of labelled red cells in the peripheral blood was more rapid in the infected calves. Radioiron uptake was depressed in the infected six-month-old calves during second week of infection but not in the sixth week. Apparent plasma volumes were increased in both groups of calves at both time periods.