Autochthonous human Hepatitis E virus (HEV) infections in industrialized countries (due to genotypes 3 and 4) are increasingly reported and are linked to zoonotic transmission, mainly through consumption of contaminated meat from pigs, Eurasian wild boar (Sus scrofa) and deer. Wild boar is deemed as the main HEV wildlife reservoir in these countries, but apart from Japan, the role deer play in HEV epidemiology is largely unknown.
This review gives an overview on the current knowledge on HEV infection and disease in wild ungulates, the risk they pose for humans and the likely routes of zoonotic HEV transmission. The compiled information should serve for proposing future research, surveillance, prevention and control. Scientific evidence suggests it is likely that wild boar infect deer with HEV when they share the habitat. Red deer (Cervus elaphus) may need a source of infection, acting as spillover host more than as a true reservoir. However, both wild ungulates can serve as an HEV source for humans. In addition, few background data on wildlife population ecology is available from the reviewed literature, which hampers the identification of HEV risk factors in wild ungulates. There is also a lack of studies that connect HEV infection in wildlife and humans. Worldwide, several human cases of HEV infections are described, but knowledge on whether the consumption of infected animals leads to clinical disease in humans is largely lacking. To meet all these challenges, cross-collaborative studies involving medics and wildlife researchers are needed. This should be a global effort to allow research to make a step forward.