Objective: To monitor trends in HIV infection and associated risk behaviours in injecting drug users (IDU) in England and Wales.
Design: Ongoing voluntary unlinked anonymous cross-sectional survey.
Method: IDU attending centres in 1990 and 1991 were invited to complete a brief questionnaire requesting demographic and behavioural information, and to provide a saliva sample to be tested for antibodies to HIV and to the core antigen of hepatitis B virus (HBV).
Results: In 1990, 1.2% (19 out of 1543) of samples from 33 centres, and in 1991 1.8% (25 out of 1417) of samples from 37 centres contained antibody to HIV. Antibody t9 HBV core-antigen was found in 33 and 31% of IDU in 1990 and 1991, respectively. The prevalence of HIV infection in IDU attending centres in London (4.2%) was higher than in those attending centres elsewhere (0.8%). The prevalence of HIV infection in 1991 varied between individual centres from 0 to 10.6%, and at many centres outside London no IDU were infected with HIV. In the same year the prevalence of past infection with HBV varied from 14 to 54%, and IDU who had evidence of HBV infection were found among attenders in nearly all centres. The prevalences of sharing injecting equipment and risky sexual behaviour were high at many centres. The prevalence of HIV infection was higher in IDU who had started to inject in 1985 or earlier, than in those who started injecting later. In each year, approximately half the IDU surveyed reported having had a voluntary confidential HIV-antibody test, and the prevalence of HIV infection was five times higher in those tested than in those who had not been tested.
Conclusions: HIV prevalence in IDU attending centres in England and Wales was low in 1990-1991. There is some indication that IDU have modified their injecting or sexual behaviour, but even at existing reduced levels of risk behaviour, transmission can occur in HIV is introduced into previously unexposed groups.