Hepatitis B in a Belgian institution for mentally retarded patients: an epidemiological study

This study describes the epidemiology of hepatitis B in a Belgian institution for mentally retarded patients. 8% of the 163 patients studied were HBs Ag carriers and 28.8% had anti-HBs. Among the HBs Ag carriers, 76.9% were HBe Ag positive. The HBs Ag carrier rate was higher in males, in patients with Down's syndrome or newcomers, and was slightly higher in patients living at parental home vs those living in the institution. A fall in the HBs Ag carrier rate was observed between the 5-14 and 15-24 age groups. A longitudinal study performed on 41 adult female patients, in the absence of any intercurrent vaccination, allowed us to determine a yearly seroconversion rate of 1.5% in this population. Data presented here confirm the risk of the institutionalized mentally retarded patients of contracting hepatitis B and becoming highly infectious HBs Ag carriers. They cast light on the various factors which have to be taken into account in this peculiar epidemiologic study and on the importance of early vaccination.