Serological and virological survey of hepatitis E virus in wild boar populations in northwestern Italy: detection of HEV subtypes 3e and 3f

Although rare in developed countries, most acquired human cases of hepatitis E virus (HEV) infection are associated with travel to developing countries where HEV is endemic. Increasingly, however, sporadic, non-travel-related HEV cases have been reported in developed countries. In Italy, only two studies to date have investigated the presence of HEV in wild boars. Here, we report a serological and virological survey of HEV in wild boar populations in northwestern Italy. During the hunting season, 594 serum and 320 liver samples were collected and screened for antibodies to HEV and HEV RNA. Overall, the seroprevalence was 4.9 %, and HEV RNA was detected in 12 liver samples (p = 3.7 %). No serum samples tested positive for HEV RNA. Phylogenetic analysis of the ORF2 region revealed that the isolates clustered within genotype 3, subtypes 3e and 3f, and were closely related to HEV strains previously detected in domestic pigs farmed in the same geographic area. Although the routes of viral transmission are still poorly understood, our data show that HEV genotypes 3e and 3f circulate in wild boars in northwestern Italy. Also, they provide evidence that autochthonous HEV infections in Italy could also be linked to wild boar populations, suggesting an increased risk for domestically acquired HEV infection in humans through wild animals. The HEV sequences determined in this study may be useful for comparing present and future human isolates to identify transmission events between wild boar, humans, and farmed pigs. Similarly to other more commonly known zoonotic agents, HEV should be included in national or regional disease surveillance programs for wild animals.