[Signs of natural infection with hepatitis A in brown macaques (Macaca arctoides)]

The results of examinations of stump-tailed monkeys (M. arctoides) held in captivity are presented. The presence and levels of anti-HAV and anti-HAV class M in the blood sera of monkeys were determined by the enzyme-immunoassay (EIA), and alanine aminotransferase (AIAT) activity was measured. HAV in stool specimens collected from the monkeys was detected by immune electron microscopy and EIA. In the first examination, 2 out of 10 monkeys were found to have anti-HAV and one of them to have anti-HAV class M. In repeat examination of 4 monkeys 32 days later, two of them showed an increase in AIAT and 3 had HAV in stools. In the 3rd examination in 91 days, all the four animals had anti-HAV and anti-HAV class M. Besides, three seronegative monkeys out of the ten examined initially, showed only total anti-HAV in 91 days. At the time of the 3rd blood specimen collection, 16 more monkeys were examined and all of these had anti-HAV but not anti-HAV class M. It is assumed that natural infection of stumptailed monkeys in captivity with a virus antigenically identical to HAV is possible.