2 ǀ HEV INFECTION IN PIGS
HEV is a zoonotic disease that can be transmitted from animals to humans. The Orthrohepevirus A affects humans, wild boar, mongoose, camel, and pigs; Orthrohepevirus B infects chickens; Orthohepevirus C causes infection in ferrets, rats, shrews, and mink, while Orthohepevirus D affects bats.37 Studies suggested that the most important reservoir for HEV genotypes capable of infecting humans is pigs.38 In 1997, the HEV was identified for the first time in pigs and pigs are recognized as the main reservoir of HEV genotypes 3 and 4.39 Several studies have been conducted on pigs infected with HEV.40-43 However, anti-HEV antibodies have been isolated from a wide range of species such as cattle, dogs, goats, deer, donkeys, sheep, and pigs.37-38,44-45
Exposure to animal feces and consumption of undercooked pork meat can cause HEV infection. Due to limited data in resource-deficient countries, Hoan et al.46 evaluated whether pigs could potentially be a source of HEV infections in Vietnam. Liver samples from domestic pigs (n = 210) and individuals serum samples exposed to pork meat and pigs (n = 283) and compared with unexposed controls (n = 168). In contrast to healthy individuals, persons occupationally acquainted with pork/pigs meat showed a high seroprevalence. Twenty-six of 210 liver tissues of pig showed HEV-RNA and detected to be HEV genotype 3. Overall, the results indicate that individuals occupationally exposed to pork meat and pigs are at associated risk of HEV. Furthermore, studies showed that HEV is reportedly associated with the consumption of meat products from wild boar and pigs.29,47-48 Therefore, in developed countries cross-species transmission is considered as the major cause of HEV infection.49-50 Figure 2 shows the transmission of HEV through a pig.