Seasonal variation in human African trypanosomiasis in Tarangire National Park in Babati district, Tanzania.

A survey was carried out to determine seasonal epidemiological variation of human African trypanosomiasis (HAT) in Tarangire National Park and villages around it in Babati District, Tanzania. Concentration and Field's stain techniques were employed to examine the presence of trypanosomes in human blood samples. Tsetse flies were collected using traps and dissected under light microscope to examine for presence of trypanosomes. Retrospective data on HAT were sought from health facilities. Blood samples were collected from a total 509 individuals (306 during the dry and 203 during wet seasons). None of the individuals was infected with trypanosomes in the area. A total of 766 tsetse flies were collected. Of these, Glossina swynnertoni accounted for 94.6% and G. pallidipes for 5.4% of the total collection. The largest proportion (63.8%) of the tsetse flies was collected during the wet season. Glossina swynnertoni was most abundant tsetse species during both wet and dry seasons. Salivary gland examination revealed the presence of Trypanosoma brucei type of infection in 3.2% of tsetse flies collected. All infective trypanosomes were found during the dry season. This study concludes that the transmission and prevalence of HAT among human population in Tarangire National Pars and its surrounding villages is low despite the recent reports on tourists acquiring the infection during their visits to the Park. However, disease surveillance needs to be strengthened to monitor any impending epidemic.