The prevalence of HBeAg and anti-HBe in an institution for the mentally retarded.

The age specific prevalence of HBsAg and anti-HBs was studied in 855 mentally retarded children and adults living in a large institution. The sera of every HBsAg positive patient was re-tested for the presence of HBeAg and anti-HBe. Overall, 78.2% of subjects showed serological evidence of current or past infection with HBV. The carrier rate was highest in children and young adults and higher amongst subjects with Down's syndrome than with other forms of retardation. HBeAg was detected in 33.9% of carriers and its prevalence also decreased with increasing age and was highest amongst subjects with Down's syndrome.