Experimental bovine trypanosomiasis (Trypanosoma vivax and T. congolense). I. Sumptomatology and clinical pathology

Twenty five cattle were infected with T. vivax, 25 with T. congolense, and 25 served as controls. Pathogenic clinical signs of trypanosomal infection were not observed. Secondary bacterial infections were common. Fever, increased heart and respiratory rates, anorexia, and emaciation developed. Elevations in parasitemai and body temperature were positively correlated in the T. vivax group. Infected groups were affected non-uniformly, with some animals in each group remaining asymptomatic and tending to have lower parasitemias. The T. vivax parasitemia was cyclic and the organisms had a genaration time of 7.9 SD 2.5 hours. The first peak of parasitemia in both infections was closely associated with the development of pancytopenia, i.e. anemia, leukopenia, and thrombocytopenia. The bone marrow erythroid response in the T. congolense group was significantly greater thn that in either the T. vivax or control groups. Leukopenia was due to concomitant neutropenia and lymphopenia.