A time-varying geospatial model of habitat suitability for Japanese encephalitis virus vectors and vertebrate hosts in Australia

In the austral summer of 2021–2022, Australia experienced an unprecedented Japaneseencephalitis virus (JEV) outbreak, with detections over 3000 km south of previousoccurrences. Given the limited knowledge of JEV transmission ecology in Australia, wedeveloped geospatial models of transmission risk to support the public health response.We created time-varying habitat suitability models for suspected mosquito vectors andardeid hosts using month-scaled occurrence and covariate data from 2000–2023. Ardeidhost presence-absence data were obtained from eBird and BirdLife Australia, withhabitat suitability estimated using gradient-boosted regression tree models. A nationaldataset of Culex occurrences was compiled from mosquito surveillance records,literature, and biodiversity databases. Penalised logistic regression was used to modelmosquito vector habitat suitability. Vector and host habitat predictions for theoutbreak peak in February 2022 were rescaled using JEV infection locations in thepublic domain to create a combined habitat suitability surface. Our models aligned withdetected JEV infections at the continental scale, highlighting transmission suitabilityacross tropical northern Australia and major inland drainage basins in the East. Unlikeexisting models, we predicted lower suitability along the eastern seaboard, suggesting adelimiting effect of the Great Dividing Range. Our approach provides the mostcomprehensive and temporally dynamic models for JEV hosts and vectors in Australia,with a significantly larger vector dataset than previous studies. The novel method ofrescaling host and vector outputs into a combined surface offers new insights into JEVtransmission risk. Favourable conditions were repeated in 2023 with few detectedinfections, emphasising that JEV ecology in Australia remains poorly understood. Thisstudy’s results can support improvements in arbovirus surveillance systems, promotingearlier detection of circulating viruses. Increased focus on vector ecology anddistributions is crucial for better understanding JEV transmission in Australia.