When a person with HIV infection uses a syringe to inject drugs, the needle is contaminated with a small amount of infected blood. If the needle is shared, the next person to use it may inject the infected blood directly into his or her own bloodstream (Chin, 2000; NIAID, 2003).
Injection drug use (IDU) accounts for only 5%–10% of worldwide HIV infections since the beginning of the HIV/AIDS epidemic. Nevertheless, in some parts of the world, IDU is the major mode of HIV transmission. For example, it is estimated that in China, Malaysia, and Vietnam at least half of HIV infections have resulted from IDU. Rapid spread of HIV through shared use of contaminated IDU equipment also has been observed in parts of Central and Eastern Europe (FHI, n.d.a). Because injection drug users are often linked in tight social networks and commonly share their injecting equipment without properly cleaning it, HIV often spreads very quickly in these populations.
In the United States in 2004, IDU transmission accounted for 29% of all African American adults and adolescents estimated to be living with HIV/AIDS, and 31% of Hispanic adults and adolescents estimated to be living with HIV/AIDS. In contrast, only 20% of estimated cases among White adults/adolescents were IDU-associated (CDC, 2005).
Injection drug use contributes to the epidemic's spread far beyond the circle of those who inject because people who have sex with an injection drug user also are at risk for infection through the sexual transmission of HIV. Children born to mothers who contracted HIV through sharing needles or having sex with an IDU may become infected as well.
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