Modelling the interactions between Herpes simplex virus type-2 (HSV-2) and HIV: implications for the HIV epidemic in Southern India

Anna M Foss (1) , Peter Vickerman (1) , Philippe Mayaud (1) , Helen A Weiss (1) , B M Ramesh (2) , Sushena Reza-Paul (3) , Reynold Washington (4) , James Blanchard (3) , Stephen Moses (3) , Catherine M Lowndes (1) , Michel Alary (5) , Charlotte H Watts (1)

1 LSHTM - London School of Hygiene and Tropical Medicine
2 Karnataka Health Promotion Trust (KHPT), Bangalore, India; and University of Manitoba, Canada
3 University of Manitoba [Winnipeg]
4 KHPT; and University of Manitoba, Canada; and St John's Research Institute, Bangalore, India
5 Unité de recherche en santé des populations, Centre hospitalier affilié universitaire de Québec

Background: The role of HSV-2 in the HIV epidemic, and the potential impact of HSV-2 suppressive therapy, have been previously explored only within the context of sub-Saharan Africa. In this analysis, modelling is used to estimate (1) the contribution of herpes simplex virus type-2 (HSV-2) to HIV transmission from clients to female sex workers (FSWs) in a Southern Indian setting; and (2) the maximum potential impact of 'perfect' HSV-2 suppressive therapy on HIV incidence. Methods: A dynamic HSV-2/HIV model was developed, parameterised and fitted to Mysore data. The model estimated the attributable fractions (AFs) of HIV infections due to HSV-2. Multivariate sensitivity analyses and regression analyses were conducted. Results: The model suggests that 36% (95% CI: 22-62%) of FSW HIV infections were due to HSV-2, mostly through HSV-2 asymptomatic shedding. Even if HSV-2 suppressive therapy could eliminate the effect of HSV-2 on HIV infectivity among all coinfected clients, only 15% (95% CI: 3-41%) of HIV infections among FSWs would have been averted. 36% (95% CI: 18-61%) of HIV infections among HSV-2-infected FSWs could have been averted if suppressive therapy reduced their risk of HIV acquisition to that of the HSV-2-uninfected FSWs. Conclusions: HSV-2 contributes substantially to HIV in this Southern Indian context. However, even in the best case scenario, HSV-2 suppressive therapy is unlikely to reduce HIV transmission or acquisition by more than 50% (as aimed for in recent trials), because of the limited strength of the interaction effect between HSV-2 and HIV.

Mots clés: EPIDEMIOLOGY; HERPES SIMPLEX; HIV; MATHEMATICAL MODEL; STDS

Anna M Foss, Peter Vickerman, Philippe Mayaud, Helen A Weiss, B M Ramesh, et al.. Modelling the interactions between Herpes simplex virus type-2 (HSV-2) and HIV: implications for the HIV epidemic in Southern India. Sexually Transmitted Infections, 2010, 87 (1), pp.22. ⟨10.1136/sti.2009.041699⟩. ⟨hal-00584273⟩