Rhinomusca as a possible vector of Habronema in Kenya

Translocations of rhinoceros in the 1990s provided an opportunity to investigate the vectors of filaria in Nairobi National Park and Solio Ranch in Kenya. These are high-altitude sanctuaries where rhinos have ulcerative sores attributed to the filarial nematode Stephanofilaira dinniki. Rhinomusca dutoiti, the biting fly closely associated with rhino, did not harbour S. dinniki, but often harboured a small and/or a large form of Habronema. Rhinomusca dutoiti from Kenya was nearly identical to R. dutoiti from South Africa based on gross morphology and a 798 base pair sequence from the 3' end of the Cytochrome Oxidase I gene. Habronema parasites occurred alone or in combination and were smaller than larval forms of H. muscae, the well-known parasite of equines. At Nairobi, prevalence of infections in the proboscis was high at 55%, with mature infections already present in young flies. This finding implied infection during larval development rather than acquisition as an adult fly. Infection patterns were similar in flies trapped or captured by hand from rhinos at Solio Ranch. Habronema was also found in a few Haematobosca spp., at much lower prevalence. Parasites were measured for several body landmarks and were photographed through light microscopy and scanning electron microscopy. These data now provide a foundation for further studies of the biology of Rhinomusca and its relationship with filarial nematodes in wildlife.