2.2.2. Preventing HIV infection
There are still few systematic reviews of the evidence on
preventive interventions in the published literature. Merson et al.
(2000) reviewed the effectiveness of projects and programmes in developing
countries that aim to reduce sexual transmission of HIV infection or
transmission related to injection drug use. They found that behavioural change
interventions are effective when targeted to populations at high risk,
particularly female sex workers and their clients. Few studies have evaluated
harm reduction interventions in injecting drug users (IDUs). Evidence on the
effectiveness of voluntary counselling and testing programmes was mixed, and
results varied according to the population being studied. STI treatment appeared
highly effective in reducing HIV/STI transmission, particularly in the earlier
stages of the epidemic. Structural and environmental interventions show great
promise, although more evaluation is needed. Merson et al. concluded
that:
· HIV prevention
interventions can be effective in changing risk behaviours and preventing
transmission in low- and middle-income countries;
· when the appropriate mix of
interventions is applied, they can lead to significant reductions in the
prevalence of HIV at the national level; and
· additional research is needed
to identify effective interventions, particularly in men who have sex with men,
youth, IDUs and HIV -infected persons.
In practice, countries will strike a pragmatic balance, based on
the capacity for programme implementation, the expected effects of
interventions, their political feasibility and the availability of financial
resources. For practical purposes, countries would need to consider
interventions aimed at reducing risk and those aimed at reducing vulnerability
(Table 1).

Table 1. Interventions for prevention
of HIV
infection