Ord River Arboviruses — Isolations From Mosquitoes

Abstract

Summary One hundred and thirty presumptive viruses have been isolated from 485 pools made from 23,872 mosquitoes collected in the Ord River area of North‐West Australia. One hundred and eleven of the virus isolates came from pools of Culex annulirostris, the dominant mosquito species caught in the vicinity of Kununurra. Forty‐five of the viruses pathogenic for newborn mice have been further characterized‐19 as Flaviviruses, 1 Alphavirus, 9 Koongol, 1 Mapputta and 15 non‐haemagglutinating viruses of which 6 are Corriparta. Thirty‐seven isolates were from Culex annulirostris. 7 from Aedeomyia catasticta and 1 from Aedes tremuls. All Corriparta isolates were from Aedeomyia catasticta. The Flaviviruses comprised 13 Kunjin and MVE isolates.

Genetic Variation of Murray Valley Encephalitis Virus

“…The similarity of the Kimberley isolates with the Charleville and Toolamba isolates of 1974 suggests a spread from the north-west of Australia to the south-east. This contention is strengthened by the fact that the Kimberley is the only proven enzootic area in Australia (Liehne et al, 1976b;Wright et al, 1981).…”

Isolation of Murray Valley Encephalitis Virus and Other Arboviruses in the Ord River Valley 1972–1976

“…The isolation data presented by Liehne et al (1976a) described a smaller number of isolates and, as such, could be presented in detail ( Table 2 of that publication). Further characterization of some of these early isolates revealed that several changes need to be made to the reported list of isolates.…”

“…The procedures used for the pooling of mosquitoes, isolation of viruses and identification of isolates have been described previously (Liehne et al, 1976a Liehne et al (1976c) and detailed collecting data from 1976 by Wright (1981). In total, 52,030 mosquitoes of 20 species have been processed into (Table 1).…”

“…A single isolate was also obtained from Charleville (Southwestern Queensland) during the 1974 epidemic in eastern Australia (Doherty et al, 1979). MVE had also been isolated from mosquitoes in Western Australia in 1972, 1973and 1974(Liehne et al, 1976a. Furthermore, serological data from the Ord Valley indicate widespread involvement of domestic mammals and domestic and wild birds in the transmission of this virus (Liehne et al, 1976b).…”

“…Mosquitoes collected in 1977 have yet to be fully processed for virus isolation. The data presented here include isolates previously reported (Liehne et al, 1976a) as many of these have been further characterized. These isolates are reviewed with respect to seasonality and intensity of activity.…”