PHLEBOTOMINE SANDFLIES IN A FOCUS OF VISCERAL LEISHMANIASIS IN A BORDER AREA OF EASTERN SUDAN

A field study was carried out in eastern Sudan, near the Ethiopian bor der, to investigate the abundance, seasonality, man-biting behaviour a nd resting sites of sandflies in two areas where visceral leishmaniasi s (kala-azar) is endemic: Umsalala village, Galabat Province; and the adjacent Dinder National Park (DNP), Dinder Province. Abundance of the different species was determined from collections made, using light a nd sticky-paper traps, in various habitats between November 1993 and F ebruary 1995. Man-biting sandflies were collected as they landed on hu man bait. The habitats investigated for day-resting sandflies were tha tched huts, chicken coops, tree-holes, termite mounds and soil cracks. Animal burrows were not investigated. The species found were Phleboto mus (Larroussius) orientalis, P. (Phlebotomus) papatasi, P. (Paraphleb otomus) saevus, P. (Anaphlebotomus) rodhaini, Sergentomyia (Sintonius) clydei, S. (Sergentomyia) antennata, S. (Sergentomyia) schwetzi, S. ( Parrotomyia) africana and S. (Grassomyia) squamipleuris. Phlebotomus o rientalis was the only man-biting sandfly species found in the DNP whe reas P. papatasi, P. orientalis and P. saevus;us were all found in Ums alala. Abundance of each species varied with the habitat. In Umsalala and a camp for game wardens in the DNP, Sergentomyia spp. predominated over Phlebotomus. In the DNP, the most abundant sandfly in a thicket dominated by Acacia seyal trees was P. orientalis, followed by Sergent omyia spp. Significant habitat 'preferences' were observed for most sa ndfly species in the area. In attempts to find resting flies, P. orien talis was only found resting in the mounds made by the termite Macrote rmes herus and P. papatasi was only found inside huts; no resting site s were detected for other Phlebotomus spp. but Sergentomyia,ia spp. we re observed in all the sites investigated. The P. orientalis in the DN P showed a clear seasonal variation in abundance, which was closely co rrelated with the mean monthly temperature and relative humidity of th e area. A remarkable increase in the abundance of this vector occurred at the beginning of the rainy season.