Epidemiologia da transmissão natural de Onchocerca volvulus (leuckart, 1893) (Nematoda, Onchocercidae) pelas espécies: Cerqueirellum oyapockense (Floch & Abonnenc, í946), Ectemnaspis bipunctata (Malloch, 1912) e Notoleprin exiguua (Roubaud, 1906) (Dipteil4, Simuliidae), em Xiteiridea, área indígena yanomami, Roraima, brasil.

Abstract

This study has been done in the Xitei/Xidea village of the Yanomami indian territory, approximately 350km from Boa Vista, Roraima State, Brazil. As this village is an hiperendemic focus of onchocerciasis, this study aimed at investigating the following aspects of vectorial transmission of each species: the factors which influente biting activity, and biting preference for human body sites. flies were caught daily from 06:OO-18:15 during 4 dayslmonth, frorn augustl95-julyl96. Every 15 min. of catch, flies were examined for species identification and age-grading. A total of three blackfly species were studied: Cerquerellum oyapockense (Floch & Abonnenc, i946), Ectemnaspis bipunctata (Malloch, 191 2) and Notolepria exiguua (Roubaud, 1 906). E. bipunctata showed a bimodal biting behaviour, whereas C. oyapockense and N. exiguua showed higher biting frequency in the afternoon. C. oyapockense and E. bipunctata bit preferencially on thoraxlneck, whereas N. exiguua did riot show preference between thoraxlneck and coxa. Most of C. oyapockense and N. exiguua flies were parous, whereas iqual numbers of E. bipunctata flies were parous or nulliparous. Only flies of C. oyapockense and N. exiguua were found infected with Onchocerca volvulus (Li and Lg stages), thus these species are probably the most important vectors in that area. Of the climatic factors investigated, temperature, relative humidity, and atmospheric pressure can be pointed as most influential for biting activity.