Epidemiology of hepatitis B in Sweden.

All the cases of clinical hepatitis B reported in Sweden since 1969 have been studied. The 10-year period 1976-1985 has been analysed intensively. For comparative purposes, the study also includes the hepatitis cases reported in 1962 and 1967. Serum hepatitis first affected young adults aged 15-24 years at the beginning of the 1960s. Cyclical outbreaks of hepatitis B due to transmission among drug abusers have been recognised since 1969. The disease was first observed in urban areas but later in rural parts of Sweden also. After 1976, a year in which outbreaks arose in various parts of Sweden, the numbers of hepatitis B cases decreased. In 1969, more than 50% of the cases reported as serum hepatitis concerned drug abusers. During the period 1976-1985, the main risk factor was drug abuse for between 20 and 52% of cases and sexual activity for between 8 and 28% of cases. Since 1969, 2-3% of cases annually have been related to blood-transfusion. In the last 5-year period, a total of 129 cases was reported among persons employed in the medical and dental fields. Of these, 59 had non-occupational exposure. During the same period, 33 patients reported contacts with infected persons, mostly household contacts. Seventy five persons had been travelling abroad.