Effect of Bacterial Endotoxin on Trypanosoma lewisi Infections in Rats

Abstract

A study was made of the effect of endotoxin on the resistance of rats to Trypanosoma lewisi. The effect on the defense mechanism of the rat was measured by a study of the parasite population during infections. Small serial doses of endotoxin given before the inoculation of trypanosomes increased the resistance of rats, while a single dose given before or simultaneously with the trypanosomes enhanced the infection. The length of time the rats were exposed to serial doses of endotoxin before challenge with trypanosomes appeared to have affected the degree of parasitemia at the peak of the infection. Endotoxin had no effect upon the period of incubation. The time of incubation varied according to the number of trypanosomes inoculated. The larger the inoculum, the shorter the incubation period.