Résumé
Trypanosoma brucei causes human African trypanosomiasis (HAT). Three subspecies were described: T. b. gambiense (Tbg) and T. b. rhodesiense (Tbr) in humans, and T. b. brucei (Tbb) in animals. Molecular markers subdivided Tbg into two groups: Tbg1 and Tbg2, of which the latter is different from Tbg1 and Tbr (absence of the SRA gene), but indistinguishable from Tbb. Tbg2 is considered to be a zoonotic form of HAT in West Africa. Tbg2 was found mainly in Côte d'Ivoire between 1978 and 1992, but the latest description was made in Ghana in 2013. New molecular tools would be welcome to characterize such infections and determine their origins (resistance to human serum or patient immunodeficiency) in the current context of HAT elimination.
Tbg2 was defined as all human-infective T. brucei trypanosomes from West and Central Africa that do not fit into the category Tbg1. Tbg2 is genetically heterogeneous, and differs from Tbg1 when using various molecular markers.Tbg2 is also genetically different from Tbr, with a consistent lack of the serum-resistance-associated gene in those strains that were tested. Tbg2, Tbb, and Tbr are highly diverse lineages that remain to be investigated more thoroughly.Tbg2 was found mainly in Côte d'Ivoire between 1978 and 1992, but the latest descriptions of Tbg2 were made in Ghana in 2003 and 2013. No other record could be found between 1992 and 2003.Tbg2 represents a zoonotic form of HAT. Human infectivity probably arose multiple times and so could do so again. In the elimination context, it is crucial to detect such infections and determine their origins (resistance to human serum or patient immunodeficiency).