Lack of correlation of anaemia with splenomegaly and hepatomegaly in Trypanosoma brucei and Trypanosoma congolense infections of rats.

Isolates of Trypanosoma brucei and Trypanosoma congolense from the blood of cattle were used to infect growing rats. Despite the use of similar infective doses, T. brucei parasitaemia appeared earlier than T. congolense parasitaemia. After the same period of parasitaemia, the degrees of anaemia, splenomegaly and hepatomegaly were similar in both infections. The percentage decrease in packed cell volume was not correlated with splenic and hepatic weights. Neither infection significantly affected the weight gain of the rats. It was concluded that both organisms caused diseases of comparable severity and that the mere enlargement of the spleen and liver made no significant contribution to the development of the anaemia.