An outbreak of Japanese encephalitis in the Torres Strait, Australia, 1995.
OBJECTIVE
To determine the distribution of virus infection during an outbreak of Japanese encephalitis (JE) in the Torres Strait, and to describe the environmental factors facilitating the outbreak.


METHODS
Human and porcine serological surveys for JE virus activity throughout the Torres Strait, and mosquito and household surveys on the island of Badu.


METHODS
The island of Badu (where the clinical cases occurred) and the other islands of the Torres Strait, Australia, during April-May 1995.


RESULTS
The serological surveys identified recent JE virus infection among residents or domestic pigs on at least nine outer Torres Strait islands. A JE virus, confirmed by nucleotide sequencing, was isolated from two asymptomatic Badu residents. Virus isolations and mosquito surveys implicated Culex annulirostris as the major vector involved in the outbreak. There was prolific Cx. annulirostris breeding in a variety of water bodies close to and within the Badu community. Over half (53%) of the households kept pigs in pens, and many (63%) of the pigpens were situated near standing water; in 56% of these "wet" pigpens Cx. annulirostris was breeding.


CONCLUSIONS
There was evidence of widespread JE virus activity throughout the outer islands of the Torres Strait. We suggest that migratory birds and/or wind-blown mosquitoes could have imported the virus into the Torres Strait from a focus of viral activity, possibly in Papua New Guinea, thereby initiating the outbreak. A combination of environmental factors, with large numbers of domestic pigs in close proximity to human dwellings and mosquito breeding sites, undoubtedly facilitated the outbreak on Badu.
Hanna
J N
JN
Tropical Public Health Unit, Queensland Health, Cairns. troppub@citec.qld.gov.au
Ritchie
S A
SA
Phillips
D A
DA
Shield
J
J
Bailey
M C
MC
Mackenzie
J S
JS
Poidinger
M
M
McCall
B J
BJ
Mills
P J
PJ
D000328:Adult; D000818:Animals; D001315:Australia / Q000453:epidemiology; D001483:Base Sequence; D009033:Culicidae / Q000821:virology; D017931:DNA Primers; D004196:Disease Outbreaks; D004283:Dog Diseases / Q000821:virology; D004285:Dogs; D004664:Encephalitis Virus, Japanese / Q000235:genetics / Q000302:isolation & purification; D004672:Encephalitis, Japanese / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D004783:Environmental Microbiology; D005814:Genes, Viral / Q000235:genetics; D006734:Horse Diseases / Q000821:virology; D006736:Horses; D006799:Housing, Animal; D006801:Humans; D007303:Insect Vectors; D008969:Molecular Sequence Data; D012689:Sequence Homology, Nucleic Acid; D013552:Swine; D013553:Swine Diseases / Q000821:virology
D017931:DNA Primers