HIV and HCV infection among injecting drug users

Background: Human immunodeficiency virus (HIV) and hepatitis C virus (HCV) are the two blood-borne pathogens most commonly transmitted among injection drug users via multi-person use of syringes and other injection equipment. However, important differences exist in the epidemiology of HIV and HCV wi thin different populations of intravenous drug users. Methods: A literature review was carried out to summarize publications desc ribing the epidemiology and natural history of HIV and HCV in injection dru g users. Results: Among injection drug users worldwide, HIV prevalence varies from < 5% to > 80%, with annual HIV incidence between < 1% and 50%. More consiste ncy is shown in HCV prevalence (50-90%) and incidence (10-30% per year). Ho st, environmental and viral factors that favor rapid spread of HCV among ID Us suggest that HCV infection in a population of injection drug users may b ecome endemic over a relatively shea period of time. Lower transmission eff iciency for HIV also indicates that its spread among injection drug users m ay be somewhat slower. Conclusions: Successful efforts to prevent transmission of blood-borne viru ses among IDUs typically result in risk reduction; however, no intervention has resulted in elimination of risk behavior. To reduce HIV transmission, risk reduction may be sufficient, whereas control of HCV may necessitate th e use of injection practices that guarantee elimination of exposure to equi pment contaminated with even small amounts of blood.