Infections of blackflies (Diptera: Simuliidae) with three types of zoonotic Onchocerca larvae in Oita, Japan

Abstract

Abstract:Wild female blackflies were collected at five cattle sheds in Oita, southern Japan, where a human zoonotic onchocerciasis had occurred. Among the eight Simulium species captured, S. bidentatum was predominant, followed by S. arakawae. Natural infections with filarial larvae were found in 10.5-20% of the parous S. bidentatum collected at three cattle sheds, and also in 6% of the parous S. arakawae captured at one cattle shed.

Infective larvae of fiveOnchocercaspecies from experimentally infectedSimuliumspecies in an area of zoonotic onchocerciasis in Japan

“…of wild boar, and O. lienalis, and determined the ability of simuliids to support development of infective larvae. The morphological characteristics of infective larvae recovered from experimental infections were compared with those of infective larvae previously described in Oita (Takaoka, 1990(Takaoka, , 1994Takaoka & Bain, 1990), and the criteria for identification of the infective larvae found in local black flies were reevaluated.…”

“…To investigate the transmission and the background of this zoonotic onchocerciasis, we have examined filariae from wild ungulates in Japan, the wild boar Sus scrofa Linnaeus, 1758, the sika deer Cervus nippon Temminck, 1838, the serow Naemorhedus crispus (Temminck, 1845), as well as cattle (Bos taurus), and the putative vectors, the black flies (Diptera: Simuliidae). These studies showed a great diversity among the genus Onchocerca as well as other Onchocercinae (Takaoka et al, 1989;Takaoka, 1990Takaoka, , 1994Takaoka & Bain, 1990;Yagi et al, 1994;Uni et al, 2001Uni et al, , 2002Uni et al, , 2004Uni et al, , 2006Uni et al, , 2007. The picture of the filarial fauna is however still incomplete, and a few kinds of microfilariae, without corresponding adult worms, remain unidentified.…”

Genetic evidence for the presence of two species ofOnchocercafrom the wild boar in Japan

“…It seems therefore reasonable to consider these two Onchocerca species from wild suids to be distinct species. In our previous investigation to search for the potential vector of zoonotic onchocerciasis in Japan, we found three types of infective filarial larvae (designated as types I, II, and III based on their size and morphology) from wild black flies collected in a cattle shed (Takaoka & Bain, 1990). In addition, we presumed that type II infective larva might be O. gutturosa of cattle, O. dewittei japonica, or the unnamed Onchocerca sp.…”

Molecular identification of infective larvae of three species ofOnchocercafound in wild-caught females ofSimulium bidentatumin Japan

“…According to our previous study (Takaoka & Bain, 1990;Fukuda et al, 2008) (Table IV). It is noteworthy that L-5 which was recovered from a female fly not reared after the collection was identified as O. dewittei japonica.…”

“…This means that S. bidentatum has an ability to support larval development of the parasite to the infective stage in nature as well as in the laboratory. Type A is presumed to be identical to type I from black flies collected in a cattle shed (Takaoka & Bain, 1990). It had been suggested that type I was L. caprini, adult worms of which were found in a serow Naemorhedus crispus (= Capricornis crispus) (Temminck, 1845) in Oita (Uni et al, 2006).…”