A dynamic 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 temporally dynamic habitat suitability models for suspected mosquitovectors and ardeid hosts using data from 2000--2023. Ardeid host presence-absence datawere obtained from eBird and BirdLife Australia, with habitat suitability estimatedusing gradient-boosted regression tree models. A national dataset of Culex occurrenceswas compiled from mosquito surveillance records, literature, and biodiversity databases.Penalised logistic regression was used to model mosquito vector habitat suitability.Vector and host habitat predictions for the outbreak peak in February 2022 wererescaled using public domain JEV infection locations to create a combined habitatsuitability surface. Our models aligned with detected JEV infections at the continentalscale, highlighting transmission suitability across tropical northern Australia and majorinland drainage basins in the East. Unlike existing models, we predicted lowersuitability along the eastern seaboard, suggesting a delimiting effect of the GreatDividing Range. Our approach provides the most comprehensive and temporallydynamic models for JEV in Australia, with a significantly larger vector dataset thanprevious studies. The novel method of rescaling host and vector outputs into acombined surface offers new insights into JEV transmission risk. Favourable conditionswere repeated in 2023 with few detected infections, emphasising that JEV ecology inAustralia remains poorly understood. This study’s results can support improvements inarbovirus surveillance systems, promoting earlier detection of circulating viruses.Increased focus on vector ecology and distributions is crucial for better understandingJEV transmission in Australia.