HIV prevention and the positive population.

Efforts to prevent the spread of HIV have, to an overwhelming degree, addressed themselves to the HIV-negative rather than to the positive population. But it makes sense to direct more preventive work towards positive individuals, for 3 reasons. First, because changes in the behaviour of positive people have a disproportionately greater effect on the spread of the epidemic--so positive-targeted interventions are potentially more cost-effective, and in many cases enormously so. Second, positive individuals already show a degree of preventive altruism that generally outweighs the self-protective efforts of those who are negative. And third, there is reason to believe that this preventive altruism can be strengthened by appropriate interventions. Some of the practical implications of a shift to greater positive targeting, involving both novel interventions and modified familiar ones, can be sketched out.