Seroprevalence of hepatitis E virus infection, rural southern People's Republic of China

Abstract

Genotype 4 hepatitis E virus (HEV) is the dominant cause of hepatitis E in the People's Republic of China; swine are the principal reservoir. Our study was conducted in 8 rural communities of southern China, where families keep pigs near their homes. Phylogenetic analysis showed that 23 of 24 concurrent virus isolates from this region are genotype 4 strains. Among the study populations, immunoglobulin G anti-HEV seroprevalence accumulated with age at approximately equal to 1% per year for persons < or =60 years of age. After age 30 years, seroprevalence increased at higher rates for male than for female study participants. The overall seroprevalence was 43% (range 25%-66%) among the communities. Infection rates were higher for participants between 25 and 29 years of age. The results suggest that HEV infection probably has been endemic in southern China for at least 60 years, with swine being the principal reservoir of human HEV infection in recent years.

Figure 1

Age specific anti–hepatitis E virus (HEV) seropositive rates in a study population. Age-specific IgG anti-HEV seropositive rates for (A) both sexes or (B) either sex separately (black triangle for male study participant, open triangle for female) were determined for every 5 years from 0 to 69 years of age and for older participants, using samples taken in 2003 from 7,284 persons.

Figure 2

Changes in immunoglobulin G (IgG) anti-hepatitis E virus (HEV) serologic status, 2003–2004. Age-specific IgG anti-HEV–positive seroconversion (A) and age-specific IgG anti-HEV–negative seroconversion (B), determined for every 5 years of age from 0 to 59 years of age and in older participants, using samples taken 12 months apart from a subpopulation of 3,431 persons.

Figure 3

Phylogenetic analysis of hepatitis E virus (HEV) isolates. HEV isolates from patients with serologically diagnosed hepatitis E cases admitted in 2003 and 2004 to local hospitals are represented by closed circles. Prototype strains of indicated genotypes are designated according to site of isolation. Numbers on the branches represent (percent) reproduced values calculated from 1,000 resamplings of the data. The bar represents a genetic distance of 0.02-nt substitution per position.