Comparison of the in vitro drug sensitivity of Trypanosoma brucei gambiense strains from West and Central Africa isolated in the periods 1960-1995 and 1999-2004.

The situation of human African trypanosomiasis remains serious with one of the main threats being the increasing number of relapses or treatment failures after melarsoprol treatment. In order to investigate and to compare drug sensitivities of trypanosomes isolated at different time periods and in different locations, two sets of Trypanosoma brucei gambiense strains were used. One set was isolated in the time period 1960-1981 and the other one in 1995-2004 from different locations of West and Central Africa. These isolates were not selected based on the treatment outcome but on availability. The drug sensitivity profile for all available drugs in use and the diamidine compound DB75 was established. IC(50) values were not significantly different between the "old" and "new" stocks. No indications for emerging drug resistance to any drug could be observed. The results indicate a relative stability of in vitro sensitivity of T. b. gambiense to trypanocidal drugs in space (West and Central Africa) and time (1960-2004).