Simuliid Blackflies (Diptera : Simuliidae) and ceratopogon midges (Diptera: Ceratopogonidae) as vectors of Mansonella ozzardi (Nematoda : Onchocercidae) in northern Argentina

Mansonella ozzardi, a relatively non pathogenic filarial parasite of man in Latin America. is transmitted by either ceratopogonid midges or simuliid b lackflies. In the only known focus of the disease in north-western Argentin a the vectors have never been incriminated. This study investigated the pot ential vectors of M. ozzardi in this area. The only anthropophilic species of these Diptera families biting man at the rime of the investigation were Simulium exiguum, S. dinellii, Culicoides lahillei and C, paraensis. Using experimentally infected flies S. exiguum and both species of Culicoides all owed full development of microfilariae to the infective stage. with C. lahi llei being a more competent host than S. exiguum. Based on these data, biti ng rates and natural infectivity rates it is probable that at the begininni ng of the wet season C. lahillei is the main vector of M. ozzardi and both C. paraensis and S. exiguum secondary vectors. Additionally, it was found t hat a single dose of ivermectin was ineffectual in eradicating M. ozzardi f rom infected individuals in this area.