The Local Reaction in Man at the Site of Infection with Trypanosoma Rhodesiense

Abstract

A problem of great importance in trypanosomiasis is what happens to the metacyclic trypanosomes when they are injected into a mammal by the bite of an infected tsetse-fly. Gordon and Willett (1956) infected guinea-pigs by the bites of tsetse-flies cyclically infected with Trypanosoma rhodesiense. By the subinoculation of heart blood into rats they showed that the blood of the guinea-pigs was infective 5 minutes, 45 minutes, 4! hours and 24 hours after the infective bite. In a fresh preparation made from the site of the bite within five minutes of its infliction, a single trypanosome was seen; and ground-up tissue, removed from the bitten area within 45 minutes of the infective feed, successfully infected white rats on two occasions. The only occasion on which they found trypanosomes on sectioning the site of bite was immediately after a fly had probed but not fed. They postulated that in guinea-pigs the majority of the metacyclic forms of T. rhodesiense deposited by the feeding tsetse rapidly migrated or were carried away from the site of the bite; that a proportion of these trypanosomes or their descendants reached the general circulation within a few hours, or sometimes within a few minutes, of the infective bite; and that, once the trypanosomes reached the circulation, they persisted in the blood throughout the incubation-period. Their guinea-pigs, however, still had an incubation-period of 7-10 days before trypanosomes were found microscopically in the blood.