Hepatitis B in the family.
During a 3-year period (1992-1995), 239 index cases of hepatitis B virus (HBV) infection and 459 members of their households from the Osijek-Baranja county were examined. The aim of the study was to determine the spread of HBV infection in the families with a member verified as a virus carrier, and to identify the family members with the highest risk of infection according to kinship degrees. The retrospective and prospective methods were used in the study. The probable route of infection was assessed by the use of an epidemiologic questionnaire, and the serologic status of the study subjects concerning infection with HBV was determined by enzyme immunoassays (HBsAg, anti-HBs, anti-HBe and anti-HBc). The first member of a family identified as a virus carrier was considered an index case. HBV infection was demonstrated in 334 (47.85%) out of a total of 698 subjects. Only 21 (6.28%) of the 334 subjects with verified HBV infection developed the clinical picture of acute hepatitis B. The ratio of clinically manifest vs inapparent infection was 1:16. Serologic traces of infection were detected in 95 of the 459 family members of the index cases, yielding a mean rate of the infection among the virus carrier family members of 20.70%.