DISTRIBUTION AND ABUNDANCE OF TRYPANOSOME (SUBGENUS NANNOMONAS) INFECTIONS OF THE TSETSE-FLY GLOSSINA-PALLIDIPES IN SOUTHERN AFRICA

Over 10 000 Glossina pallidipes tsetse flies were collected during two field studies in the Zambezi Valley, Zimbabwe and one in the Luangwa Valley, Zambia. These were screened for mature trypanosome infections and 234 dot-blot preparations were made of infected midguts, which wer e screened using DNA probes or PCR with primers specific to different species or types of the trypanosome subgenus Nannomonas. Over 70% of m idgut infections were successfully identified as either Trypanosoma go dfreyi, T. simiae or three types of T. congolense, savannah, riverine- forest and Kilifi. The relative abundance of species and types did not vary significantly between study locations, habitat, season or tsetse age or sex, although there were differences between DNA probe and PCR results. Mixed species and/or mixed type infections were common and w ere more often defected using PCR. The distribution of infections amon g flies was highly aggregated, but there was no tendency for multiple infections to accumulate in older flies, implying that sequential supe rinfection may be uncommon. Possible explanations for these patterns a re discussed.