Epidemics of ruminant arboviral diseases such as Akabane, Aino, and bluetongue have periodically occurred in Kyushu, Japan. Culicoides brevitarsis is likely one of the important vectors transmitting the etiological pathogens of these diseases, although its presence has so far been recognised primarily in Okinawa Prefecture. In entomological surveys in 2008 and 2009, C. brevitarsis was collected at 9 sites through Nagasaki, Kumamoto, and Kagoshima Prefectures in Kyushu. The collection sites are located near pastures, in which cattle were grazing and the larvae of C. brevitarsis could grow in dung left in the field. C. brevitarsis has been confirmed at three collection sites for 2 consecutive years, suggesting that it overwinters in Kyushu. C. oxystoma has been the most likely incriminated vector of ruminant arboviruses in the southern part of Japan, but its larvae require swampy grounds, such as paddy fields, for growth. C. brevitarsis probably plays some role in the transmission of ruminant arboviruses in arid areas in which C. oxystoma cannot maintain its lifecycle. Given the risk of arbovirus transmission, the ecology of C. brevitarsis in Japan, including distribution range, seasonal abundance, and larval breeding sites, should be investigated in more detail.
(Subtropical Disease Research Division)
References:
Yanase T. et al (2011) J. Vet. Med. Sci. 73 (12):1649-1652
