Serological survey on hepatitis A and B infections among the residents of social welfare homes in Singapore

A study of the immunological status of hepatitis A and B infections was carried out among the residents of eight social welfare homes in Singapore. The sample population consisted of 440 individuals of whom 55% were Chinese, 21% were Malays and 24% were Indians. The mean age of the study population was 14 years and 4 months. The immunological markers studied included specific IgM antibody and total antibody against hepatitis A virus (anti-HAV-IgM and total anti-HAV respectively); hepatitis B surface antigen (HBsAg), surface antibody (anti-HBs), core antibody (anti-HBc) and e antigen (HBeAg), all tested by the enzyme immunoassay (EIA) technique.
While none of the subjects had detectable anti-HAV-IgM (HAVAB-M-EIA), 12% were positive for total anti-HAV (HAVAB-EIA) indicating evidence of past infection. HBsAg was detected (Auszyme II) in 4.5% and of these, half had HBeAg (Abbott-HBe EIA). Anti-HBs positivity (AUSAB-EIA) occurred in 11.6% and the majority (88%) of these had anti-HBc positivity (CORZYME) as well. The positive rate for anti-HBc alone was 3.6% reflecting the 'window' period after the fall of HBsAg and before the rise of anti-HBs. At least one of the hepatitis B markers was present in 19.1% of the study population.
The endemic nature of both hepatitis A and B infections in the local population is evident, with infection occurring in all ethnic groups at an early age.