The prevalence of hepatitis E virus (HEV) in domestic pigs is between 10% and 30%, with a likelihood that infected pigs enter the pork production chain thereby threatening public health, indicate Portuguese study results.
Fecal samples from just over a fifth of pigs from five industrial pig farms included in the study tested positive for HEV RNA, with a higher detection rate in younger than older animals, report the researchers.
Furthermore, all HEV-positive samples that were sequenced by polymerase chain reaction (PCR) were genotype 3 - which "together with genotype 4, is found to be responsible for human autochthonous HEV infection in industrialized countries," says the team.
"Considering that zoonotic spread has been proposed, this study provides insight on HEV sequences circulating in the pig population in Portugal...[where] there is a strong tradition of pork consumption," comment Alessandra Berto (Wageningen University and Research Centre, Lelystad, the Netherlands) and co-workers.
The team collected 40 pig fecal samples between December 2010 and February 2011 from five farms containing every age group of pig: weaners, growers, fatteners, and sows.
Samples were tested via PCR and sequencing and phylogenetic analysis, which revealed the presence of HEV-positive feces at every farm in the study. Indeed, HEV-positive feces was detected in pigs from every age group, at 32% in weaners and fatteners, 20% in growers, and 4% in sows.
The overall prevalence of HEV-positive samples was 22%, report Berto and colleagues.
One HEV-positive sample from each farm was randomly selected to undergo realtime PCR, and all five sequences were characterized as genotype 3, write the researchers in Zoonoses and Public Health.
"There is now compelling evidence that in industrialized countries, human HEV infection mainly originates from swine," they explain, adding that with the results presented in their study, "it is clear that HEV is highly circulating."
They conclude that in Portugal: "HEV-infected animals are likely to enter the pork production chain and hence HEV contaminations in the food chain are likely to occur. This could be an increasing public health concern."
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