Molecular detection of Japanese encephalitis virus and Murray Valley encephalitis virus in mosquitoes: implications for disease transmission in the Northern Territory, Australia

2025-07-02

Kurucz, Nina

Roberts, Alexander

Weir, Richard

Bhardwaj, Vidya

De Araujo, Rachel

Currie, Bart

Mahar, Jackie

Neave, Matthew

Mileto, Patrick

Williams, David

Medical Entomology, Centre for Disease Control, Public Health Division, NT Health, Darwin, Northern Territory, Australia,

Berrimah Veterinary Laboratory, Department of Agriculture and Fisheries, Darwin, Northern Territory, Australia

Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia

CSIRO, Australian Centre for Disease Preparedness, Geelong, Victoria, Australia

Journal Article

Publication

In 2021, Japanese encephalitis virus (JEV) reverse transcription quantitative RT-qPCR testing of mosquitoes was used for the first time in the Northern Territory (NT) in an attempt to determine the presence of circulating JEV and identify probable vector mosquito species. All test results for 2021 and 2022 returned negative for JEV. Testing resumed in January, 2023, with mosquitoes also tested for Murray Valley encephalitis virus (MVEV) following an outbreak resulting in eight confirmed human cases. Mosquito pools tested positive by RT-qPCR for both viruses on several occasions, confirming the suitability of this method for flavivirus surveillance. Culex annulirostris (Skuse) and Cx. gelidus (Theobald) tested RT-qPCR positive for both viruses in 2023, incriminating them as JEV and MVEV vectors in the NT. Aedes normanensis (Taylor) also tested positive for JEV and MVEV, identifying this species as a probable vector species for both viruses in the NT. While Cx. annulirostris is known to be the principal MVEV vector in the NT, the fact that all three vector mosquito species potentially play a part in the JEV transmission cycle is of major public health concern. While Cx. tritaeniorhynchus (Giles) did not test positive to JEV in 2023, this species is the principal JEV vector in SE Asia and could potentially play a role in JEV transmission in the NT. Genotyping of viruses from the NT mosquitoes confirmed the continued circulation of genotype IV JEV and showed that both genotypes 1A and 2 of MVEV were co-circulating in the NT in 2023.

link

Journal of Vector Ecology 50 (2), 82-92, (2 July 2025) https://doi.org/10.52707/1081-1710-50.2-82

1948-7134