Prevalence of hepatitis B infection in long-stay mentally handicapped adults.

The objective was to determine the prevalence of hepatitis B virus (HBV) infection in long-stay institutionalized mentally handicapped adults and to develop a vaccination programme for them. The study was carried out in 1994. The subjects were 171 mentally handicapped adults aged 37-76 (median age 56) with a median hospital stay of 30 years (range 6-47). Markers for infection were determined using ELISA. Seronegative patients were vaccinated using the standard schedule, and the titre of antiHBs reached was determined later. The prevalence of seropositive subjects was 81.3%. Seropositive subjects had a longer hospital stay (median stay of 32 years, range: 15-47) than seronegative ones (median stay of 15 years, range: 6-33). A total of 43.3% of the vaccinated subjects developed antiHBs antibodies (GMT: 135 IU/l). The high prevalence of HBV exposure is probably a legacy of a past era which is reflected in patients with prolonged institutionalisation in a closed regime. The need for immediate vaccination of mentally handicapped subjects is of the utmost importance, as it has been shown that the response to the vaccine worsens with age.