Epidemiologia da Transmissão Natural de Onchocerca volvulus (Leuckart, 1893) (Nematoda, Onchocercidae) por Psaroniocompsa incrustata (Lutz, 191 0) (Diptera, Simuliidae) em Xitei

Abstract

Monthly and daily adivities 0f Psaroniocompsa incrustata (Lutz, 191 0) were studied. Some epidemiological and behavioral aspects of this species were observed such as human body parts preferentially bitten, physiological conditions of the ovaries, natural infection rates with Onchocerca volvulus, seasonality and relationship with climate factors. Blackflies were collected during one complete year (augustl1995 to july/1996) with the collaboration of a volunteer indian at XiteiMidea post, located 350 km from Boa Vista, Yanomami territory, Roraima state, Brazil. The collections were made during 4 days beginning at 6:00 AM and finishing at 6:15 PM, divided in groups of 15 minutes alternating the collection with the volunteer's rest. The results showed the trunk as the most prefered bitten spot followed by the thighs. The parous flies presented more activity then nulliparous flies with different patterns of abundance during dry and wet season. All development stages of 0.volvulus larvae were found in P.incrustata, including the infective form, demonstrating the role of P.incrustata as a vector of onchocerciasis at XiteiMidea area. The infective larvae forms (4) were only found at the most abundant period for P,incrustata, the wet season, showing a positive relatioship between abundance of specimens and infective females. Climate-factors analyses showed that temperature, relative humidity, atmospheric pressure and light intensity are the primary factors influencing daily-biting activities.