Pathogen specific prevention strategies

Risk-reduction strategies that are successful for HIV may be insufficient for the prevention of HCV because of the differences in dynamics of transmission. As previously discussed, HCV and HBV tend to be acquired within the first few years of injection, during which injection drug users are less likely to come into contact with prevention and treatment services (Garfein et al, 1996). Persons entering methadone maintenance and attending needle exchanges tend to have on average 10 years of injection experience, so they have most likely already acquired HCV and HBV (Schutz et al, 1994). Thus, modified strategies need to be explored to provide effective prevention from these viruses.

For hepatitis B prevention, effective use and distribution of the HBV vaccine is critical. However, although a safe and effective vaccine has been available for more than 20 years, rates among injection drug users remain low (Seal et al, 2000). There have been successful efforts to vaccinate injection drug users, suggesting that this is a possibility, but infrastructure is needed to identify individuals who are both uninfected and at highest risk (Seal et al, 2003). This means targeting individuals early, before, or soon after injection initiation.

Prevention of HCV is further complicated by the lack of an effective vaccine. Often hepatitis C is viewed by injection drug users as either unavoidable or of less importance than HIV (Davis et al, 2004; Rhodes et al, 2004). Risk reduction and prevention of HCV needs to be distinguished from that for HIV, and there is a need to develop HCV-specific prevention and treatment strategies. As with HBV, the risk in the first year of injection is so high that efforts need to be made to reach drug users before they initiate injection. However, accessing these populations has proven to be difficult. A more comprehensive approach, including transition prevention messages, in addition to the current education regarding the consequences of non-injection drug use, may be more effective at reducing HCV transmission (Wodak and Lurie, 1997; Vlahov et al, 2004). Finally, relevant for prevention of all blood-borne infections but most critical for HCV, prevention messages need to alert injection drug users to the harm associated with all equipment sharing, rather than only injection sharing. Perhaps needle-exchange programs should also consider proactive distribution of injection paraphernalia, in particular cookers and cotton filters. Some studies have shown that HCV prevalence among injectors in places with comprehensive harm-reduction programs is lower than in other industrialized countries, again reinforcing the need for programs to be established early (Hope et al, 2001).

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