Population Genetics of Trypanosoma brucei gambiense: A Clone in the Dark
Human African trypanosomiasis (HAT) (or sleeping sickness) due to Trypanosoma brucei gambiense) occurs in Western and Central Africa. T. brucei s.l. displays a huge diversity of adaptations and host specificities, and questions about its reproductive mode, dispersal abilities, and effective size remain under debate. We have investigated genetic variation at eight microsatellite loci of T. b. gambiense strains isolated from HAT patients in Côte d’Ivoire and Guinea, with the aim of knowing how genetic information was partitioned within and between individuals, between foci and between temporally spaced samples. The results indicate that (i) migration of T. b. gambiense group 1 strains does not occur at the scale of West Africa, and that even at a finer scale (e.g. within Guinea) migration is restricted; (ii) effective population sizes of trypanosomes as reflected by infected hosts are probably higher than what the epidemiological surveys suggest; and (iii) T. b. gambiense group 1 is most likely a strictly clonally reproducing organism.