High prevalence of antibodies against hepatitis A virus among captive nonhuman primates.

Hepatitis A virus (HAV) can infect not only humans but also several other nonhuman primates. This study has been conducted to evaluate the comprehensive anti-HAV seroprevalence in captive nonhuman primate populations in Thailand. The prevalence of antibodies against HAV in 96 captive nonhuman primates of 11 species was evaluated by competitive enzyme immunoassay (EIA). HAV antibodies were found in 64.7% (11/17) of macaques, 85.7% (6/7) of langurs, 28.4% (10/35) of gibbons, and 94.6% (35/37) of orangutans. However, anti-HAV IgM was not found in any sera. These results indicate that the majority of captive nonhuman primates in Thailand were exposed to HAV. It is possible that some of the animals were infected prior to capture.