Detection of anti-HEV antibodies and RNA of HEV in pigs from a hyperendemic Italian region with high human seroprevalence

Background: Pigs are considered the main reservoir of genotypes 3 and 4 of hepatitis E virus (HEV), which is the major cause of acute hepatitis of viral origin in humans worldwide. An increasing number of autochthonous HEV infections have been observed in recent years in industrialized countries, most likely as a result of zoonotic transmission through the consumption of raw or undercooked meat products. Methods: Two hundred and thirty-three blood and liver samples were collected at four different local slaughterhouses from domestic pigs bred in Abruzzo, a region of south-central Italy, where there is the highest human seroprevalence to HEV compared with the rest of Italy. An indirect enzyme-linked immunosorbent assay kit was used for detecting anti-HEV IgG in the sera, while the presence of HEV RNA was investigated by performing a real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Results: Between 87.3% and 100% of swine serum samples collected in different slaughterhouses of Abruzzo were positive for anti-HEV antibodies. Conversely, none of the liver samples collected from the same animals were positive for HEV by real-time RT-PCR. Conclusions: The hypothesis of foodborne zoonotic transmission from local pigs as responsible for the hyperendemic status of Abruzzo cannot be corroborated. However, the high seroprevalence observed in pigs indicates that HEV is highly circulating in these territories. We propose to further investigate the role of wild fauna and trade in carrier pigs, and the maintenance of HEV virulence in the environment and meat supply chain to shed light on the possible sources of human infection and the degree of occupational risk.