Seroprevalence of hepatitis A antibodies among residents of a centre for people with developmental disabilities

Abstract Background: In February 1993,11 cases of hepatitis A virus (HAV) were identified in permanent residents of a centre for young people with developmental disabilities. Aims: To define the extent of the outbreak in the centre, to determine the seroprevalence of hepatitis A antibodies (anti-HAV) in permanent residents, and to ascertain risk factors for serological evidence of HAV infection. Methods: A cross-sectional serological survey of 270 permanent residents, aged eight to 40 years, in a centre for people with developmental disabilities, was conducted in western Sydney. Using a radioimmunoassay technique, sera were tested for anti-HAV (IgM and total antibody). We used logistic regression to determine risk factors for presence of anti-HAV. Results: Blood samples were collected from 259 permanent residents (96%). Serological testing revealed anti-HAV in 128 residents tested (49%). Presence of anti-HAV was associated with living in specific residential units, and with residents' age and length of stay at the centre, but was not associated with reported behavioural factors. Conclusions: More than half of the residents of the centre were susceptible to HAV infection. Behavioural characteristics of the residents and their close contact with each other make HAV transmission difficult to control. HAV vaccine should be promoted in communities at risk, such as those with developmental disabilities. (Aust NZ J Med 1994; 24: 365–367.)