Can Behavior Change Explain Increases in the Proportion of Genital Ulcers Attributable to Herpes in Sub-Saharan Africa?

In Brief Background The proportion of cases of genital ulcer disease attributable to herpes simplex virus type 2 (HSV-2) appears to be increasing in sub-Saharan Africa. Goal To assess the contributions of HIV disease and behavioral response to the HIV epidemic to the increasing proportion of genital ulcer disease (GUD) attributable to HSV-2 in sub-Saharan Africa. Study Design Simulations of the transmission dynamics of ulcerative sexually transmitted diseases (STDs) and HIV with use of the model STDSIM. Results In simulations, 28% of GUD was caused by HSV-2 before a severe HIV epidemic. If HIV disease was assumed to double the duration and frequency of HSV-2 recurrences, this proportion rose to 35% by year 2000. If stronger effects of HIV were assumed, this proportion rose further, but because of increased HSV-2 transmission this would shift the peak in HSV-2 seroprevalence to an unrealistically young age. A simulated 25% reduction in partner-change rates increased the proportion of GUD caused by HSV-2 to 56%, following relatively large decreases in chancroid and syphilis. Conclusion Behavioral change may make an important contribution to relative increases in genital herpes. Modeling scenarios suggest that behavioral responses to the HIV epidemic may have contributed markedly to observed increases in the proportion of genital ulcer disease due to herpes simplex virus type 2 in sub-Saharan Africa.