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

Abstract

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.