Estudos sobre a transmissão de Mansonella (Nematoda: Onchocercidae) por Culicoides (Diptera: Ceratopogonidae) na comunidade de Assunção, Rio Içana, Amazonas

Abstract

The genus Culicoides is a group of ceratopogonid of medical and veterinary importance, widely distributed throughout the world, with more than 1400 species. Of these, 96% are obligatory blood feeding of birds and mammals. They are responsable for parasite transmission to man and other animals, besides causing skin damage and allergy. Both nematodes and viruses can be transmitted to humans. The objective of this work was to survey the Culicoides fauna in the community of Assunção, Rio Içana, Amazonas state, Brazil, and to verify the relationship of these species in the transmission of filariasis caused by filaria of the genus Mansonella, where riverine human populations where found infected by microfilárias of M. perstans and M. ozzardi. Sampling occurred in November 2007 and February 2008, periods of lower and higher rainfall, respectively. The insects were caught using CDC light traps, direct collection in infected human volunteers and active search for possible breeding places. The midges were identified, and the females collected in blood activity were dissected in a stereoscopic microscope and then observed on the optical microscope. We identified 16 species, of which two are new species. One of them is Culicoides (Hoffmania) sp.n1, from the hylas group, and the other Culicoides sp.n.2 from the reticulatus group. The most abundant species was Culicoides caprilesi, followed by C. debilipalpis and C. paraensis and the presence of insects varies differently with the temperature, atmospheric pressure and air humidity. C. caprilesi reached the maximum activity in the afternoon, and his presence was positively correlated to temperature. C. debilipalpis’ activity peak was in the morning, with a positive correlation to atmospheric pressure and relative humidity. Among the 1.916 insects dissected, a female of C. paraensis was infected by Mansonella perstans in the second larval stage, which is the first meeting of M. perstans in female of Culicoides in the South America. Larvae of Culicoides were collected in fruits open cupuaçu containing accumulated water, which characterizes it as a new record of a breeding site for the group.