COMPARISON OF BLACK FLY SPECIES (DIPTERA, SIMULIIDAE) ON AN AMERINDIAN RESERVATION WITH A HIGH PREVALENCE OF FOGO SELVAGEM TO NEIGHBORING DISEASE-FREE SITES IN THE STATE OF MATO-GROSSO DO SUL, BRAZIL

Fogo selvagem is an autoimmune blistering skin disease that principall y occurs among rural Brazilians living in geographically clumped disea se foci. Exposure to hematophagous black flies possibly is related to the cause of the disease. We compared the occurrence, proportions, and richness of simuliid species immatures and the biting activity of adu lt females within a recently discovered, high prevalence focus of fogo selvagem, the Limao Verde Terena Reservation, to that of neighboring regions with no reported cases of fogo selvagem. Nine black fly specie s were collected from 12 stream sites during 5 trips to the fogo selva gem focus. The species showed longitudinal (upstream-downstream) trend s in occurrence, proportions, and richness, and the abundance of simul iid immatures was greater at downstream sites. The most prevalent spec ies at the focus, Simulium nigrimanum (Macquart), dominated the stream sites with highly abundant simuliid assemblages, and was the most com mon black fly in human bait collections. This species was absent ol in very low numbers in neighboring valleys and villages that did not hav e cases of fogo selvagem.