Biomedical subjects

S A Ritchie

Publications and source records attributed to S A Ritchie.

57 records · Page 4Linked to original sources

PubMedDate not supplied

Japanese encephalitis on Badu Island, Australia: the first isolation of Japanese encephalitis virus from Culex gelidus in the Australasian region and the role of mosquito host-feeding patterns in virus transmission cycles.

During investigation of an outbreak of Japanese encephalitis (JE) in the Torres Strait, Australia, in 2000, mosquitoes were collected in Badu Island community and at a newly established communal piggery about 3 km from the community. A total of 94,285 mosquitoes, comprising 91,240 (96.8%) unengorged females, 1630 (1.7%) blood-engorged females and 1415 (1.5%) males, were processed for virus isolation. One isolate of JE virus was obtained from Culex gelidus, with a minimum infection rate of 12.4:1000. This is the first isolate of JE virus from Cx. gelidus in the Australasian region. No isolates were obtained from Cx. annulirostris, the primary implicated Australian JE vector. Analysis of mosquito host-feeding patterns, using gel diffusion, demonstrated that Cx. annulirostris and 5 other species fed predominately on mammals. Analysis of blood-fed mosquitoes collected within the community demonstrated that the proportion of Cx. annulirostris feeding on pigs in 2000 (2.3%) was significantly lower than that for the 1995-97 period (31.3%). The removal of the pigs from Badu Island community has limited the contact between potential amplifying hosts and mosquitoes, thus potentially reducing the risk of transmission of JE virus to the human population.

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PubMedDate not supplied

Wind-blown mosquitoes and introduction of Japanese encephalitis into Australia.

Backtrack simulation analysis indicates that wind-blown mosquitoes could have traveled from New Guinea to Australia, potentially introducing Japanese encephalitis virus. Large incursions of the virus in 1995 and 1998 were linked with low-pressure systems that sustained strong northerly winds from New Guinea to the Cape York Peninsula.

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PubMedDate not supplied

Flaviviruses isolated from mosquitoes collected during the first recorded outbreak of Japanese encephalitis virus on Cape York Peninsula, Australia.

In response to an outbreak of Japanese encephalitis (JE) virus on Cape York Peninsula, Australia, in 1998, mosquitoes were collected using CO2 and octenol-baited Centers for Disease Control and Prevention light traps. A total of 35,235 adult mosquitoes, comprising 31 species, were processed for virus isolation. No isolates of JE virus were recovered from these mosquitoes. However, 18 isolates of Kokobera virus, another flavivirus were obtained from Culex annulirostris. Twelve isolates were from western Cape York (minimum infection rate (MIR) of 0.61: 1,000 mosquitoes) and 6 were from the Northern Peninsula Area (MIR of 1.0:1,000). Potential explanations for the failure to detect JE virus in mosquitoes collected from Cape York Peninsula include the timing of collections, the presence of alternative bloodmeal hosts, differences in pig husbandry, asynchronous porcine seroconversion, and the presence of other flaviviruses.

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