Abstract
Prevalence levels of HIV infection among injecting drug users rapidly reached 50% or more in several cities worldwide (e.g. New York, Edinburgh, Bangkok); other cities have seen sustained lower levels of infection, and in some cases declining incidence. Research evidence indicates that many long term drug injectors now have high levels of HIV transmission awareness, and that they are able to change their behaviour to reduce risk of infection. Public health interventions (bleach, syringe distribution) and drug treatment (methadone) enable behavioural change. Risk reduction for needle and syringe sharing is more common than for sexual behaviour. Condom use remains low and selective. Despite changes in behaviour, current residual levels of risk probably remain high enough to ensure continued spread of infection. Improved prevention efforts must focus on initiating and sustaining change, sexual behaviour, and methods for reaching harder-to-reach populations (women, younger injectors, non-urban populations, prisoners).