Nearly 30 years into the HIV epidemic, injection drug users (IDUs) remain at high risk for HIV infection. Data from surveillance systems and cohort studies have collectively suggested that HIV infection incidence among IDUs has declined a trend attributed at least in part to harm-reduction measures including needle exchange programs (NEPs) and substance-abuse treatment. Hepatitis C virus (HCV) is nearly 10 times more transmissible by needlestick than is HIV .
Prevalence estimates of HCV infection among IDUs have been reported to exceed 50% in most IDU populations, ranging as high as 95% . Sharing a needle even once is enough to transmit or acquire HCV . Harm reduction measures that have led to declines in HIV infection incidence have not been as successful for HCV infection. HCV transmission is almost exclusively parenteral, in contrast to the multiple routes of transmission for HIV.
Source: inef.ie, 02/02/2011