[Distribution and spread of human African trypanosomiasis: value of genetic identification of the trypanosomes].

Numerous factors extrinsic to trypanosome populations have been implicated in the distribution and spread of human African trypanosomiasis (HAT), but quantification of these factors has proven difficult. An easier method of monitoring HAT consists of tracking parasites by genetic identification of trypanosomes in hosts and vectors. This method requires distinction between Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense followed by determination of the genotype of each subspecies in the host and vector. The role of vertebrate hosts in the distribution and spread of HAT has been confirmed by genetic identification of trypanosomes. Despite the ever-improving performance of biomolecular techniques, identification must be carried out on natural populations actually circulating in the biological fluids of the host and vector. This precaution is necessary to rule out the biasing effect of in vivo or in vitro isolation of trypanosomes.