Prevalence and Risk Factors for Hepatitis E Virus in Wild Boar and Red Deer in Portugal

Hepatitis E virus (HEV) is a zoonotic foodborne virus with an annual infection prevalence of 20 million human cases, which seriously affects public health and economic development in both developed and developing countries. To better understand the epidemiology of HEV in Central Portugal, a cross-sectional study was conducted from 2016 to 2023 with sera samples from wild ungulates. The seroprevalence and risk factors for HEV seropositivity were evaluated in the present study. Specifically, antibodies against HEV were determined by a commercial enzyme-linked immune-sorbent assay (ELISA). Our results show that in the 650 sera samples collected from 298 wild red deer and 352 wild boars in Portugal, 9.1% red deer and 1.7% wild boar were positive for antibodies to HEV. Regarding age, the seropositivity in juvenile wild ungulates was 1.3%, whereas it was 7.2% in adults. Logistic regression models investigated risk factors for seropositivity. The odds of being seropositive was 3.6 times higher in adults than in juveniles, and the risk was 4.2 times higher in red deer than in wild boar. Both wild ungulate species were exposed to HEV. The higher seroprevalence in red deer suggests that this species may make a major contribution to the ecology of HEV in Central Portugal. Further research is needed to understand how wildlife affects the epidemiology of HEV infections in Portugal.