The role of glossina pallidipes in the epidemiology of sleeping sickness in the serengeti national park

Human African Trypanosomiasis (HAT) is an infectious and neglected disease caused by Trypanosoma brucei rhodesience transmitted by various Glossina species. G. pallidipes is endemic to all foci of HAT in Tanzania; however the species has not been implicated for the transmission of the disease in all epidemic outbreaks in the past. A study to determine density, infection rate and host preference of G. pallidipes was conducted during the end of the dry season and at the end of the wet season at the Death Valley in the Serengeti National Park. Tsetse flies were captured using NGU and NZI traps which were deployed into two, 2 Km long transects in a wooded grassland for ten days in each season. Out of 53,161 flies caught, 77.48% were identified as G. pallidipes and 22.52% as G. swynnertoni. The overall tsetse apparent densities were 84.9 Flies per Trap per Day (FTD) and 180.9 FTD at the end of the rain and the end of the dry season, respectively. The apparent density varied with species (p = 0.001), season (p = 0.001) and sex (p = 0.001). Out of 1053 tsetse flies dissected 50.2% were G. pallidipes and 49.8% were G. swynnertoni. Two percent (2%) of both species (G. pallidipes and G. swynnertoni) were infected with trypanosomes. Trypanosoma species which infected G. pallidipes included T. congolense (17.19%), T. vivax (10.94%), T. brucei (5.08%) and T. b. rhodensiense (0.07%). Syncerus caffer (African buffalo), Giraffa camelopardalis (Giraffe), Phacochoerus africanus (Warthog), and Loxodonta africana (African elephant) were the main hosts of G. pallidipes, with the African buffalo being the most preferred. It was concluded that G. pallidipes is an important vector in the epidemiology of HAT, as was observed to be infected with trypanosomes associated with this diseases. A transmission study is recommended in the future to investigate the vectorial capacity of G. pallidipes in the area.