characterization of trypanosome infections by polymerase chain reaction pcr amplification in wild tsetse flies in cameroon the polymerase chain reaction pcr method was used to characterize trypanosome infections in tsetse flies from 3 sleeping sickness foci in cameroon the predominant tsetse species found was glossina palpalis palpalis an average infection rate of 121 was revealed by microscopical examination of 888 nonteneral tsets flies pcr amplification analyses for trypanosome identification were carried out on 467 flies with primer sets specific for trypanosoma trypanozoon brucei s1 t duttonella vivax t nannomonas simiae and forest type t nannomonas congolense of 467 flies 93 were positive by microscopical analysis while pcr succeeded in identifying 89 positive flies of the pcrpositive flies 34 382 were negative by microscopical examination pcr amplification when compared to the parasitological technique gave a higher estimate of infection rate of trypanosomes in natural tsetse populations the pcr technique did however fail to identify 409 3893 of the parasitologically positive flies the reasons for this failure are discussed the overall prevalence of mixed infections assessed by pcr was 371 the majority 727 involved t brucei and forest type t congolense