Abai, MR

6th International Congress of DipterologyExperimental and natural infections of black flies (Diptera:Simuliidae) with larvae of Onchocerca dewittei japonica, thecausative agent of zoonotic onchocerciasis in JapanFukuda, M. (1, 2), C. Aoki (2) & H. Takaoka (1, 2)(1) Institute of Scientific Research, Oita University, Hasama, Yufu City, Oita 879-5593,Japan(2) Department of Infectious Disease Control, Faculty of Medicine, Oita University,Hasama, Yufu City, Oita 879-5593, JapanTo determine the vector(s) of Onchocerca dewittei japonica Uni, Bain andTakaoka, a common filaria parasite of wild boars and the causative agentof zoonotic onchocerciasis in Japan, we investigated the experimental andnatural infections of female black flies with larvae of this parasite. Themicrofilariae of O. dewittei japonica were injected intrathoracically into 86newly-emerged females of seven Simulium species collected in Oita, Japan.After 10 days post-infection, the third-stage larvae were found in 4 of 21 S.aokii (Takahasi) dissected, 12 of 14 S. arakawae Matsumura, 6 of 11 S.bidentatum (Shiraki), 1 of 1 S. japonicum Matsumura, 1 of 1 S.quinquestriatum (Shiraki) and 3 of 4 S. rufibasis Brunetti. No larva wasfound in 1 S. uchidai (Takahasi) dissected. The infective third-stage larvaewere 772–1,059 µm long by 17–22 µm wide. It has been proved for thefirst time that these six black-fly species are able to support the larvaldevelopment of O. dewittei japonica. Moreover, female adult black fliesattracted to a man and/or an automobile were collected in the field andmaintained in tubes with sugar solution for 10 or 11 days until dissections.One of 100 S. bidentatum and 1 of 11 S. quinquestriatum examined hadone third-stage filaria larva. The third-stage larvae found from fieldcollectedS. bidentatum was 964 µm long by 21 µm wide, and that from S.quinquestriatum was 856 µm long by 25 µm wide. Morphometric analysisshows that the former filarial larva is likely to be O. dewittei japonica.These findings may suggest a possibility that black flies play a role in thetransmission of zoonotic onchocerciasis due to O. dewittei japonica inJapan.78