High risk landscapes of Japanese encephalitis virus outbreaks in India converge on wetlands, rainfed agriculture, wild Ardeidae, and domestic pigs

Japanese encephalitis constitutes a significant burden of disease across Asia, particularly in India, with high mortality in children. This zoonotic mosquito-borne disease is caused by the Flavivirus, Japanese encephalitis virus (JEV), and circulates in wild ardeid bird and domestic pig reservoirs both of which generate sufficiently high viremias to infect vector mosquitoes, which can then subsequently infect humans. The landscapes of these hosts, particularly in the context of anthropogenic ecotones and resulting wildlife-livestock interfaces, are poorly understood and thus significant knowledge gaps in the epidemiology and infection ecology of JEV persist, which impede optimal control and prevention of outbreaks. The current study investigated the landscape epidemiology of JEV outbreaks in India over the period 2010 to 2020 based on national human disease surveillance data. Outbreaks were modelled as an inhomogeneous Poisson point process. Outbreak risk was strongly associated with the habitat suitability of ardeid birds and pig density, and shared landscapes between fragmented rainfed agriculture and both river and freshwater marsh wetlands. Moreover, risk scaled with Ardeidae habitat suitability, but was consistent across scale with respect to pig density and rainfed agriculture-wetland mosaics. The results from this work provide a more complete understanding of the landscape epidemiology and infection ecology of JEV in India and suggest important priorities for control and prevention across fragmented terrain comprised of wildlife-livestock interface that favours spillover to humans.