Prevalence and Risk Factors for Hepatitis E Virus (HEV) in Wild Boar (Sus scrofa) and Red Deer (Cervus elaphus) 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 the Centre of 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 collected from 298 wild red deer and 352 wild boars from Portugal, 9.1% red deer (95% confidence interval [CI]: 6.312.9%) and 1.7% wild boar (95% CI: 0.63.3%) were positive for antibodies to HEV. Regarding age, the seropositivity in juvenile wild ungulates was 1.3% (95% CI: 0.273.72%) and 7.2% in adults (95% CI: 4.910.11%). Logistic regression models investigated risk factors for seropositivity. The odds of being seropositive was 3.6 higher in adults than in juveniles (95% CI: 1.7218.11%) and the risk was 4.2 higher in red deer than in wild boar (95% CI: 1.64–10.69%). Both wild ungulate species were exposed to HEV. The higher seroprevalence in red deer suggests that this species may have a major contribution to the ecology of HEV in the Centre of Portugal. Further research is important to understand how wildlife affects the epidemiology of HEV infection in Portugal.