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Modelling the interactions between herpes simplex virus type 2 and HIV: implications for the HIV epidemic in southern India
  1. Anna M Foss1,
  2. Peter T Vickerman1,
  3. Philippe Mayaud1,
  4. Helen A Weiss1,
  5. B M Ramesh2,3,
  6. Sushena Reza-Paul4,
  7. Reynold Washington2,3,4,
  8. James Blanchard3,
  9. Stephen Moses3,
  10. Catherine M Lowndes1,5,
  11. Michel Alary6,
  12. Charlotte H Watts1
  1. 1London School of Hygiene and Tropical Medicine, London, UK
  2. 2Karnataka Health Promotion Trust, Bangalore, India
  3. 3University of Manitoba, Manitoba, Canada
  4. 4St John's Research Institute, Bangalore, India
  5. 5Health Protection Agency, London, UK
  6. 6Unité de recherche en santé des populations, Centre hospitalier affilié universitaire de Québec, Québec, Canada
  1. Correspondence to Dr Anna Foss, Department of Global Health and Development, Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, 15–17 Tavistock Place, London WC1H 9SH, UK; anna.foss{at}


Background The role of herpes simplex virus type 2 (HSV-2) in the HIV epidemic and the potential impact of HSV-2 suppressive therapy have previously been explored only within the context of sub-Saharan Africa. In this analysis, modelling is used to estimate the contribution of HSV-2 to HIV transmission from clients to female sex workers (FSW) in a southern Indian setting and 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 of HIV infections due to HSV-2. Multivariate sensitivity analyses and regression analyses were conducted.

Results The model suggests that 36% (95% CI 22% to 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 co-infected clients, only 15% (95% CI 3% to 41%) of HIV infections among FSW would have been averted. 36% (95% CI 18% to 61%) of HIV infections among HSV-2-infected FSW could have been averted if suppressive therapy reduced their risk of HIV acquisition to that of HSV-2-uninfected FSW.

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.

  • Epidemiology
  • female sex work
  • herpes simplex virus type 2
  • HIV
  • India
  • mathematical modelling
  • STD

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  • Funding Support for this research was provided by the Bill & Melinda Gates Foundation (BMGF) through Avahan, its India AIDS Initiative (grant no 33978), and the Department for International Development (DFID) funded Knowledge Programme on HIV/AIDS and STI and the Research Programme Consortium for Research and Capacity Building in Sexual and Reproductive Health and HIV in Developing Countries of the LSHTM. MA is a national researcher of the Fonds de la Recherche en Santé du Québec (grant no 8722). The views expressed herein are those of the authors and do not necessarily reflect the official policy or position of LSHTM, the BMGF/Avahan or DFID. The Mysore data were collected as part of the monitoring and evaluation of the multisite HIV prevention intervention funded by the BMGF.

  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the Ethics Review Boards of St Johns Medical College and Hospital, Bangalore, the Centre hospitalier affilié universitaire de Québec, Québec, Canada and the University of Manitoba, Canada. For monitoring and evaluation of the Avahan intervention in India, ethical approval has also been obtained from the Ethics Review Board of the Centre hospitalier affilié universitaire de Québec, Québec, Canada.

  • Provenance and peer review Not commissioned; externally peer reviewed.