The pathogenesis of infection with Trypanosoma vivax in goats and cattle.

The pathology of Trypanosoma vivax (stock Y-486) in East African goats (Galla cross Masai) and Friesian cattle was studied sequentially. In both goats and cattle parasitaemia was detectable six to seven days after inoculation with 1 X 10(5) trypanosomes. The goats were more susceptible than cattle as indicated by higher parasitaemias, more severe anaemia and death in 25 per cent of the goats. The major pathological changes occurred in the lymph nodes, spleen, eyes, pituitary gland, testicles and heart. There was marked, generalised lymph node enlargement associated with an increase in the number and size of lymphocytic follicles accompanied by germinal centre formation. The medullary cords of the lymph nodes were distended and distorted by the high population of plasma cells. Similar changes were noted in the spleen. However there was no evidence for extramedullary erythropoiesis in both organs. Inflammatory changes were noted in the eyes, pituitary glands, testicles and heart.