Seroepidemiology and genetic characterization of hepatitis E virus in western Yunnan Province

Objective:To investigate the seroepidemiology and genetic characterization of hepatitis E virus(HEV) in western Yunnan Province.Methods:Questionnaire survey was conducted among1638 residents in western Yunnan Province using stratified sampling method.Enzyme-linked immunosorbent assay was used to detect serum anti-HEV IgG and IgM.HEV RNA was extracted from patients with serum anti-HEV IgM positive.The open reading flame 2(ORF2) of HEV that was amplified by nested RT-PCR was sequenced and compared with standard HEV genotypes 1-4.Results:Serum anti-HEV positive was found in 13.929(228/1638) residents.The HEV infection rate in males was significantly higher than that in females with a ratio of 1.47(P<0.01).20-30 and30-40 years old young men showed the highest incidence.20.57%and 20.78%.respectively.While10-20 and 20-30 years old young women exhibited the highest infection rate,11.85%and 15.60%,respectively.According to occupation,the highest HEV infection rate was observed in farmers(20.35%) and migrants(16.50%).We isolated 10 individual HEV isolates from 31 patients with serum anti-HEV IgM positive.Homology analysis and phylogenetic analysis indicated that these10 HEV isolates belonged to HEV genotype 4 with the homology of 78.65%-94.71%.Conclusions:The HEV infection rate is high in western Yunnan Province.HEV genotype 4 is the leading cause of HEV infection and young farmers and migrants are the main infected population.