Mosquito isolates of Ross River virus from Cairns, Queensland, Australia

During 1996-1998 60,619 mosquitoes were collected around Cairns, Australia and processed for Alphavirus isolation. Thirty-three isolates of Ross River (RR) virus were made from 9 species, Aedes imprimens, Aedes kochi, Aedes n otoscriptus, Aedes vigilax, Culex annulirostris, Culex gelidus, Mansonia se ptempunctata, Verrallina (formerly Aedes) carmenti, and Verrallina lineatus . Attempts to isolate RR virus from 121 Aedes aegypti were unsuccessful. Tw enty six (79%) of the isolates came from within 1 km of a colony of spectac led flying-foxes, Pteropus conspicillatus. The minimum infection rate for t hese mosquitoes was 1.0 compared with 0.2 per 1,000 for mosquitoes trapped at all other sites. Ross River virus has not previously been isolated from Ae. imprimens, Cx. gelidus, Ma. septempunctata, Ve. carmenti, or Ve. lineat us. This is also the first isolation of an arbovirus from Cx. gelidus in Au stralia. In conclusion, the vector status of Ve. carmenti, Ae. aegypti and Mn. septempunctata warrants further study. This study also provides evidenc e that P. conspicillatus may be a reservoir host.