Effects of splenectomy on Trypanosoma congolense infection in cattle.

The role of the spleen in cattle infected with Trypanosoma congolense was studied by comparing levels of parasitaemia, blood cell values, and body weights of intact and splenectomized cattle. A total of 28 Zebu x Hereford steers were used in two separate experiments. Seven animals were splenectomized at least four weeks prior to infection and two others were splenectomized 128 days after infection. Splenectomized animals were compared to 12 intact infected animals and seven intact uninfected controls. The splenectomized animals suffered no less severe anemia and no higher parasitaemia than the intact, infected cattle. Splenectomy in two animals during infection had no effect on packed cell volumes, parasitaemia or survival. Splenectomized cattle have lower levels of circulating lymphocytes following treatment than intact animals; also, the splenectomized steers lost more weight during the active infection.