Constant Hepatitis E Virus (HEV) Circulation in Wild Boar and Red Deer in Spain: An Increasing Concern Source of HEV Zoonotic Transmission

Hepatitis E is a viral zoonosis that affects multiple hosts. The complete dynamics of infection in wildlife are still unknown, but the previous fact facilitates the maintenance and circulation of the virus, posing a risk to human health in the case of meat consumption from susceptible animals. In Spain, it has been shown how domestic pigs, cattle and wildlife (i.e. wild boar and red deer) clearly interact in hunting farms, generating a complex epidemiological situation in terms of interspecies pathogen transmission. Therefore, in this study, we aimed to (i) evaluate the circulation of the virus in geographically close domestic (Iberian pigs) and wild animals (wild boar and deer) living in hunting areas from central Spain over an 8-year period (2003-2010) and (ii) to determine whether HEV could be used as a marker of domestic-wildlife contact. For these purposes, a longitudinal analysis of Iberian pig, wild boar and red deer samples (n = 287) through virological and serological tests was conducted to shed light upon the circulation events of HEV. Regarding HEV RNA detection by real-time RT-PCR, 10.12% samples (95% CI: 5.44-14.8) from wild boar and 16.05% samples (95% CI: 8.06-24.04) from red deer were positive. As for the Iberian pigs, none of the 48 samples was positive for HEV RNA detection. In the serological analysis, 43.75% (95% CI: 29.75-57.75) from Iberian pig, 57.40% (95% CI: 48.10-66.70) from wild boar and 12.85% (95% CI: 5.01-20.69) samples from red deer presented anti-HEV antibodies. Positive samples were distributed among all study years (2003-2010). These results depict the urgent need to improve the inspection and surveillance of these species and their products. In the case of HEV, it is clear that the stable and constant presence of the virus in wildlife and its contact with Iberian pigs pose a risk for human health as they are all destined for human consumption.