SUSCEPTIBILITY AND RESISTANCE TO TRYPANOSOME INFECTION

Abstract

The trypanosome T. evansi was used, with the guinea pig as host, and the effect of short exposures to direct sunlight on the course of the infection determined. Exposure for 5-15 min. reduces the incubation period, increases frequency and intensity of invasions of the circulation, and decreases duration of the illness, which always ended fatally. Insolation through water to eliminate the heat factor did not alter the effect. Control animals in total darkness had longer incubation periods, longer illness, and in general manifested greater resistance to infection. Immersion of animals in a water bath without insolation also reduces incubation period and duration of illness. The lowering of resistance to trypanosome infection which follows immersion or exposure to sunlight for short intervals may be referable to the same causes responsible for malarial relapses on exposure to light or chilling.