A spectrum of disease in Human African trypanosomiasis: the host and parasite genetics of virulence

Abstract

SUMMARYFor over 50 years it has been known that there are considerable differences in the severity and rate of progression of bothTrypanosoma brucei rhodesiense and T. b. gambienseinfection between individuals. Yet research into the factors, whether parasite or host, which control virulence in Human African trypanosomiasis is in its infancy. In this paper we review the clinical evidence for virulence variation and the epidemiological and experimental data that give clues as to the mechanisms involved. Evidence will be presented for both asymptomatic forms ofT. b. gambienseinfection and low virulence forms ofT. b. rhodesienseinfection in humans. While in both cases the mechanisms remain to be elucidated, the overall infection virulence phenotype is determined by both parasite and host genotype.