UNAIDS in its December 2005 report on the global AIDS epidemic presented the modeled impact of different prevention and treatment programs in reducing annual HIV incidence in SSA.[1] The HIV scenario selected by these modelers as the “baseline” for comparing future HIV incidence assumed that risk behaviors continued at what the modelers believed to be the current levels, and without any major increase in anti-retroviral treatment (ART) programs. Based on their assumptions, the modelers projected a level and unchanging (“stable”) prevalence rate in SSA over the duration of the projection – 20 years.

These modelers completely ignored the major factor responsible for peaking in all infectious disease epidemics – the phenomena of saturation of infection in persons who are at risk of infection. Thus, unless HIV risk behaviors begin to increase, HIV incidence will slowly decrease after reaching a peak. How much of the future decrease in annual HIV incidence might be attributed to public health prevention programs and how much to a natural decrease can and will definitely be the subject for heated debate for the rest of this decade! Models that project unrealistic increases in HIV incidence will just serve to exaggerate the effectiveness of current prevention programs!

[1] Salomon JA, Hogan DR, Stover J, et al (2005) Integrating HIV prevention and treatment: From slogans to impact. PLoS Med. 2(1): e16. [January 11, 2005].