High seroprevalence of hepatitis E virus in the ethnic minority populations in Yunnan, China

Hepatitis E virus (HEV) infection is relatively high in the southern regions of China. Yunnan, located in southwestern China, has the highest number of ethnic groups. However, HEV infection in the ethnic population is largely unknown. Therefore, we aimed to investigate the seropositive rate, risk factor, and clinical impact of HEV infection in the ethnic groups of Yunnan. We recruited 1912 individuals from four minority groups in three prefectures of Yunnan province. Epidemiological records on potential risk factors for exposure to HEV and blood biochemical index were analyzed. All the serum samples were tested for anti-HEV IgM/IgG by enzyme-linked immunosorbent assay, and the IgM-positive samples were subjected to nested reverse transcription-PCR to detect HEV RNA. Overall, 1273 individuals (66.58%) were positive for anti-HEV IgG, 16 (0.84%) for anti-HEV IgM, and 64 (3.35%) for anti-HEV IgG and IgM both; none of them had detectable HEV RNA. Multivariate analysis revealed a strong statistical association between ethnic origin and HEV IgG seroprevalence. Anti-HEV IgG reactivity in the Hani ethnic (82.3%; 401/487) population was higher than that in the Naxi (71.9%, 340/473), Bulang (65.1%; 302/464), and Wa (60.2%; 294/488) ethnic populations (p < 0.0001). Older age and male sex were independently associated with the risk of past HEV infection. Moreover, anti-HEV IgG-positive individuals showed significantly higher levels of total and direct bilirubin and alanine amino transferase but significantly lower levels of globulin and low-density lipoprotein, than the respective levels in anti-HEV IgG-negative individuals. Thus, the seroprevalence of HEV infection is high in the ethnic populations of Yunnan, China. It is therefore necessary to increase the surveillance of specific risk groups and raise awareness about the possible infectious diseases to help limit the HEV transmission here.