The prevalence of serological markers, hepatitis B virus DNA and elevated serum amino transferase values in institutionalized mentally handicapped males and females: an epidemiological study of HBV infection in residents with Down's syndrome or other forms of mental deficiency.

Conventional HBV serological markers, as well as serum alanine amino transferase and hepatitis B virus DNA (HBV DNA) were studied in a population of 667 institutionalized mentally handicapped males and females and in 676 staff members. The role of Down's syndrome (DS), sex and age-related factors with respect to the prevalence of these markers was analyzed. A young age at admission was found as one of the important factors in the development of the chronic HBsAg carrier state in females. The well-known higher prevalence of HBsAg carriership in DS patients appeared to be restricted to males. Markers indicative of viral replication, HBeAg and HBV DNA, were also more prevalent in male than in female DS residents, or OMR residents. These findings indicate that the phase of active viral replication is prolonged in male HBsAg carriers with DS. However, only 66.7 per cent of HBV DNA-positive and 26.2 per cent of HBsAg-positive residents had abnormal serum alanine aminotransferase (ALT) values. In addition, more than 50 per cent of residents with elevated serum alanine amino transferase values were negative for HBV serological markers. We conclude that male DS residents are the main source of HBV infection in institutions for the mentally handicapped and that determination of ALT values is not very useful in identifying those HBsAg carriers capable of transmission the infection.