Delta infection and drug abuse in Merseyside.

Delta agent is a small RNA virus which depends on hepatitis B virus for replication. Infection with delta virus in Britain and other countries in Northern Europe and North America is largely confined to drug abusers and their social contacts. In Merseyside, between 1982 and 1987, we found evidence of delta virus infection in 10 (4.4%) of 224 cases of acute hepatitis B in drug abusers. Among carriers of hepatitis B surface antigen (HBsAg) with a history of drug abuse, however, the proportion with delta antibody rose from 10% in 1984 to 30.8% in 1987. Among all HBsAg carriers identified in 1986 and 1987, delta antibody was detected in 11 (32.4%) of 34 with a history of drug abuse but in only 3 (1.6%) of 183 in whom drug abuse was not admitted. Long-term delta infection in these carriers is often associated with development of chronic active hepatitis and represents a major problem not only in countries where hepatitis B and delta virus infections are endemic but also potentially among drug abusers in Britain. Control of delta virus infection depends on social action to curb drug abuse and on the use of hepatitis B vaccine where appropriate to prevent hepatitis B in those at risk. In order to monitor the prevalence of delta virus infection in the community, priority should be given to testing for delta antibody HBsAg carriers with a history of drug abuse.