Targeting interventions for the prevention of HIV infection in developing countries: when to begin targeting non-core groups.

The issue of the point at which non-core groups should be targeted in acquired immunodeficiency syndrome (AIDS) prevention programs requires clarification. The number of secondary human immunodeficiency virus (HIV) infections attributable to the non-core group rises with increases in the HIV prevalence rate in this sector. Moreover once the HIV prevalence rate exceeds 12-15% the number of infections generated from within the non-core group actually surpasses the number attributable to members of the core. Thus interventions aimed only at core groups reach a group that generates a progressively smaller number of new HIV infections. The issue of non-core groups merits attention for other reasons: first an exclusive focus on core groups can create a false sense of security for those outside these populations and second people may create their own socially unacceptable methods for avoiding contact with members of the core group (e.g. men having sex with very young girls rather than prostitutes). Thus efforts should be made to develop effective prevention campaigns targeted at both core and non-core groups.