Prevalence and phylogenetic analysis of hepatitis E virus in pigs in Vietnam

Abstract Background: Hepatitis E virus (HEV) is one of the important zoonotic diseases with a worldwide distribution. The main objective of this study was to assess the sero-prevalence and phylogenetic analysis of HEV in Vietnam. Pig blood and fecal pooled samples were used to determine the prevalence of HEV. We evaluated the true prevalence (TP) of HEV from apparent prevalence (AP) by taking into account the sensitivity and specificity of diagnostic tests using a Bayesian approach. For phylogenetic analysis, the data compared with worldwide HEV reference strains illustrating all eight genotypes (G1-G8) which were identified in previous study. Results: A total of 475 sera and 250 fecal pooled samples were collected at slaughterhouses and pig farms from five provinces, in Viet Nam. Overall, the AP of HEV was 58.53% (95% CI: 53.95-62.70) while the TP was slightly higher (59.96%, 95% credible interval: 54.49-65.41). In terms of pooled samples, overall, the AP (13.38%, 95% credible interval: 9.89-17.30) of HEV was much higher than TP (6.80%, 95%CI: 4.01-10.66). One strain in Hanoi, two strains in Dak Lak, seven strains in An Giang, four strains in Son La and two strains in Nghe An were isolated. The phylogenetic tree demonstrated that 19 Vietnamese strains were clustered into HEV 3 and 4. Conclusions: This study provided evidence that HEV is circulating in domestic pigs in Vietnam. From a public health perspective, it is very important to raise public awareness for high-risk groups (e.g. slaughterhouse workers, pig traders, farmers and market sellers) who have more opportunities to come in contact with pig and contaminated meats.