Hepatitis B in a residential population with a mental handicap.

Hepatitis serology was used to assess the nature and extent of hepatitis B virus (HBV) infection in the population of a residential centre for people with a mental handicap comprising 56 with Down's Syndrome (DS) and 193 with other mental handicaps (OMH). Markers of HBV were present in 170 cases (68%), of which 25 (10%) were HBsAg positive and potential carriers and 145 IgG anti-HBc positive (58%) indicating exposure to but not necessarily immunity from the virus. Of 25 who were HBsAg positive five were HBeAg positive, 17 were anti-HBe positive, two were HBsAg positive only and one was anti-HBe plus IgM anti-HBc positive. Age and length of residence were significantly associated with HBsAg, IgG anti-HBc and total markers of infection but the degree of mental handicap was not and the DS/OMH ratio only with HBsAg. The results indicated widespread HBV infection, no acute disease cases, relatively few infectious cases and a pre-disposition of DS residents to retain HBsAg in their sera. Vaccination of staff and at risk residents is recommended.