Preliminary Entomological and Parasitological Studies in Humboldt, Aripuanã, Mato Grosso State, Brazil.

Abstract

ABSTRACT The preliminary results are given of studies on the sandfly fauna (Diptera: Psychodidae) in forest surrounding the Humboldt Research Centre, Municipio of Aripuanã, Mato Grosso State, Brazil. A total of 712 sandflies were obtained, including 26 different species: of these, 387 were caught off human bait; 317 from tree-trunks; 4 in a malaise-trap; 3 in rodent baited oil traps; and 1 in a light-trap. Man-biting species were absent or very rare during studies in the dry season (August and September, 1974), but relatively abundant at the end of the rainy season (June, 1975): this suggests a seasonal transmission of leishmaniasis. The species at present known as Lutzomyia anduzei of Floch & Abonnenc (1942) was a major man-biter, this species is an important vector of cutaneous leishmaniasis in North Pará, Brazil, and could be responsible for transmission in Aripuanã. Among a total of 349 female sandflies dissected, promastigote flagellates were found in 2 Lutzomyia yuilli; epimastigote flagellates in 1 L. yuilli; a microsporidian in Psychodopygus (1) complexus; a gregarine, probably Monocystis chagasi, in P. davisi; and a nematode larva in P. complexus. Inoculation of the promastigote flagellates into the skin of hamsters failed to give Leishmania infections: possibly they were developmental stages of some other parasite. Two research workers of Project RADAM acquired cutaneous leishmaniasis in the Humboldt area; and 6 cases of malaria were diagnosed, 3 due to P. falciparum and 3 to P. vivax. Transmission of malaria was shown to be taking place in the camp site itself. Finally, man-biting "black-flies" (Diptera: Simuliidae) were found to be a serious problem, necessitating constant use of insect repellent.