Seroepidemiology of hepatitis A virus infection in southern Taiwan.

Hepatitis A virus infection was common in Taiwan. Most of the Taiwan data on the prevalence of Hepatitis A virus antibody (anti-HAV), however have derived from the Taipei area and few reports are available on the age-specific prevalence in other parts of Taiwan. Sera of 738 healthy inhabitants in Tainan District, a rural southern Taiwan, were collected from January to December, 1992, and screened the anti-HAV IgG by radioimmunoassay. The prevalence rate of anti-HAV among infants was 64.6%, which decreased to 3.3% in preschool and school-age children up to 12 years old. The prevalence rate of anti-HAV antibodies was over 92% in adult subjects beyond 30 years of age, and 82.4% among 34 pregnant women. Compared to the data obtained from the children living in Taipei City, our results showed that the prevalence rate of anti-HAV in age group 1 to 10 years in Tainan area was higher than Taipei City (2.3-3.7% vs. 0-0.5%, 0.03 < P < 0.09). The data also indicated that the age of primary infection in children has extended to an older age group. The rarity of HAV infection in Taiwan has created a large growing population of susceptible young adults. Mass vaccination for this population should be considered in the preventive program of public health.