Background HIV/AIDS has a manifest ability to swell to epidemic proportions and debilitate entire societies. Currently, the disease remains below the level of a generalised epidemic1 in the USA and many other developed nations. Yet the number of reported HIV infections continues to expand steadily.2 The same strains of virus affect all humans, but their ecology and epidemiology are markedly different in opposite-sex vs same-sex communities. Variance terms in the transmission equations of opposite-sex communities are reduced in same-sex communities, changing the dynamics of the disease and the interventions that could successfully control it.

Methods and Results We apply mathematical disease models of minimal complexity and higher complexity equation-free network models to show how (1) purely epidemiological forces are sufficient to explain the rapid spread of the virus through male same-sex communities, independent of usual assumptions of more dangerous or careless sexual practices in those communities3, (2) the expansion tendencies of HIV can be counteracted in national testing and treatment programs aimed at breaking the spread of infection, and (3) simple behavioural changes resulting from increased awareness of infection through increased testing4 can conceivably bring the infection under control in the heterosexual community, even without universal voluntary testing.5

Conclusions Much world effort properly is being focused where the disease is rampant, as in opposite-sex communities in many African nations6 as well as male same-sex communities everywhere.7 Critical attention must be continued in these sensitive populations, but attention throughout the general population is called for as an additional pre-emptive measure. Our results illustrate how expanded efforts in low-prevalence heterosexual communities throughout the developed world could moderate the expanding infection there, arrest it before it reaches run-away levels, and conceivably cause it to decline and eventually vanish from the general population.