Figure 1. Epidemic typologies based on an alternative framework.

High-risk groups (pink box) comprise of female sex workers, high-risk men who have sex with men, and injection drug users. Yellow circles indicate direct sexual partners of members of a high-risk group (for example, male clients). Grey boxes comprise the remainder of the general population. Red lines delineate sexual partnerships that contribute to emergence and persistence of HIV in the local community (epidemiologic drivers), such that in the absence of these partnerships, the epidemic would fail to establish.