Risk of hepatitis B in a ward for mentally retarded HBsAg carriers.

A screening of 615 mentally retarded residents in a Finnish institution revealed 22 HBsAg-positive asymptomatic carriers in 1972. Thirteen of them were placed in a special ward and followed up for 12 years. Only one patient had hepatitis eight years later. During the years all 52 staff members of the ward and the laboratory had been HBsAg-negative, but one laboratory nurse and two ward nurses showed antibody production. The seroconversion rate was one per 33 person-years among the staff. The results suggest that the risk of transmitting hepatitis B still exists, even in special wards in such institutions, and isolation of the carriers alone cannot guarantee full protection for hepatitis B infections.