Trypanosoma vivax diagnosis : an unresolved problem in the epidemiology of trypanosomoses

Abstract

Trypanosoma (Duttonella) vivax is a parasite infecting domestic ruminants in Africa and Latin America. Stocks in Latin America, mechanically transmitted by various biting insects, seemed to have lost their ability to infect tsetse flies which periodically transmit them in sub-Saharan Africa. The authors reviewed various diagnosis techniques used in T. vivax detection in the field, such as standard parasitological examinations, serological tests and molecular techniques (PCR). The most sensitive and specific technique appeared to be PCR, used at the CIRDES, Bobo-Dioulasso, Burkina Faso. The results obtained with this technique to identify T. vivax in cattle and tsetse mouthparts were compared to parasitological results from recent studies in West Africa. The most striking fact was that in some areas a significant number of tsetse flies, infected in the proboscis only (T. vivax cycle), gave no amplification signal with any of the sets of primers used. The authors examined several hypotheses to explain these results. The most probable one seemed to be the presence of Duttonella subgenus stocks that were not recognized by the markers used. It should be worthwhile carrying out genetic and pathogenic studies on field-isolated stocks.