ABSTRACT
The first case of Japanese encephalitis (JE) in the Northern Territory occurred during 2021 in Wurrumiyanga, Bathurst Island, in the Tiwi Islands at the northwestern edge of the NT. Wet season mosquito surveillance commenced in response to the JE case, which comprised of adult mosquito trapping and larval mosquito surveys. The program was carried out from 2021 to 2024. Generally low mosquito numbers were collected, and there was an absence of large wetlands in Wurrumiyanga. However, several known Japanese encephalitis virus (JEV) vector species were detected, with Culex annulirostris the most abundant vector collected during the mosquito surveillance program.
Potential JEV host animals such as pigs and waterbirds were also present in and nearby to Wurrumiyanga. Despite the low vector abundance, the presence of known vector mosquitoes and host animals suggested there was the possibility for local epizootic transmission. However, there were no further JE cases from Wurrumiyanga. Lack of major mosquito breeding sites may have contributed to there being no further JE cases in Wurrumiyanga. The NT JEV vaccination program, community awareness, source reduction via drain maintenance and methoprene 30-day residual insecticide treatments may also have played a role in the absence of further cases.