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 tr ypanosome infections in tsetse flies from 3 sleeping sickness foci in Cameroon. The predominant tsetse species found was Glossina palpalis p alpalis. An average infection rate of 12.1% was revealed by microscopi cal examination of 888 non-teneral tsetse flies. PCR amplification ana lyses for trypanosome identification were carried out on 467 flies, wi th primer sets specific for Trypanosoma( Trypanozoon) brucei s.l., T. (Duttonella) vivax, T. (Nannomonas) simiae and forest type T. (Nannomo nas) congolense. Of 467 flies 93 were positive by microscopical analys is while PCR succeeded in identifying 89 positive flies. Of the PCR-po sitive flies 34 (38.2%) were negative by microscopical examination. PC R 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 40.9 % ( 38/93) of the parasitologically positive flies. The reasons for this f ailure are discussed. The overall prevalence of mixed infections, asse ssed by PCR, was 37.1 %; the majority (727 %) involved T. brucei and f orest type T. congolense.