Seroepidemiology of Hepatitis A Infection in Northeastern China, Korea, and Japan

OBJECTIVES The epidemiological patterns of endemic hepatitis A virus (HAV) are unclear in northeastern Asia depending on the ethnicity of the country in question. The purpose of this study was to investigate the seroprevalence of HAV in northeastern China, South Korea, and Japan. METHODS A total of 1,500 serum samples were collected from five groups of inhabitants (300 each) who were over 40 years of age (Korean Chinese, indigenous Chinese, South Korean, Korean living in Japan, and indigenous Japanese). The samples were screened for antibodies to HAV using an enzyme-linked immunosorbent assay. RESULTS Positivity for HAV antibodies was 93.7% (95% confidence interval [CI]: 90.9-96.4) in Koreans living in northeastern China, 99.7% (95% CI: 99.0-100.3) in indigenous Chinese, 98.0% (95% CI: 96.4-99.6) in indigenous Koreans, 33.3% (95% CI: 28.0-38.7) in Koreans living in Japan, and 20.4% (95% CI: 15.8-25.0) in indigenous Japanese persons. The overall anti-HAV prevalence was not significantly different between northeastern China and South Korea, but it was different in Japan. CONCLUSIONS These results indicate that differences in seroprevalence can be attributed to geological, environmental, and socioeconomic conditions rather than ethnicity.