Herpes simplex virus type 2 (HSV-2)

Published: 07 April 2009

Essentially all studies of HIV and HSV-2 have found that having HSV-2 at least doubles the risk of becoming infected with HIV, and the effect has been even greater in some studies.1 One large meta-analysis2 found that having HSV-2 doubled the risk of contracting HIV in MSM, and tripled the risk in women and men in the general population. Another systematic review of studies3 found that HSV-2 conferred nearly a three-fold risk increase in developed countries and a 4.3-fold increase in MSM. Other studies have found even greater effects: a four-fold increase in HIV risk with chronic HSV-2 and five-fold with recent HSV-2 infection for women;4 5 a nearly six-fold increase in highly exposed sex workers,6 and an eight-fold higher risk in women in Uganda and Zimbabwe.7

Consistently higher risk has been found with recent, as compared to chronic, HSV-2 infection. Although risk is higher when active ulceration due to HSV-2 is present, there is still an elevated risk even when visible ulcers are absent.

HIV and HSV-2 each appear to drive the transmission of the other. In people who are co-infected, HIV infection leads to greater shedding of HSV-2, and HSV-2 reactivation in turn leads to increased HIV genital shedding. This is especially the case during active, ulcerative HSV-2 reactivation ('outbreaks'), but is not restricted to such outbreaks – more copious and/or more frequent genital shedding of HIV has also been seen during asymptomatic HSV-2 infection when ulcers are not apparent.8 3 9 10 11 This increased HIV shedding has also been seen despite successful antiretroviral treatment.12

How this increased shedding of HIV actually affects infectiousness (risk of causing infection) is a distinct question, and one that is harder to study because of confounding factors such as STIs in the at-risk partner. HSV-2 has been shown to increase risk of onward transmission four-fold in one study.3 One study of HIV-positive gay men in San Diego found that when the source (HIV-positive) partner had HSV-2 and the HIV-negative partner did not, it made HIV transmission 16 times more likely.13

References

  1. Celum C et al. Genital herpes and human immunodeficiency virus: double trouble. Bulletin of the World Health Organization 82(6): 447-53, 2004
  2. Freeman EE et al. Herpes simplex virus 2 infection increases HIV acquisition in men and women: systematic review and meta-analysis of longitudinal studies. AIDS 20:73-83, 2006
  3. Corey L et al. The effects of herpes simplex virus-2 on HIV-1 acquisition and transmission: a review of two overlapping epidemics. J Acquir Immune Defic Syndr 35: 435-44, 2004
  4. Capiga SH et al. The role of herpes simplex virus type 2 and other genital infections in the acquisition of HIV-1 among high-risk women in Northern Tanzania. JID 195 (May 1), 2007
  5. Corey L Herpes simplex virus type 2 and HIV-1: the dialogue between the 2 organisms continues. JID 195 (May 1), 2007
  6. Kaul R et al. Monthly antibiotic chemoprophylaxis and incidence of sexually transmitted infections and HIV-1 infection in Kenyan sex workers: a randomized controlled trial. JAMA 291: 2555-2562, 2004
  7. Brown JM et al. Incident and prevalent herpes simplex virus type 2 infection increases risk of HIV acquisition among women in Uganda and Zimbabwe. AIDS 21:1515-1523, 2007
  8. McClelland RS et al. Association between cervical shedding of herpes simplex virus and HIV-1. AIDS 16: 2425-2430, 2002
  9. Le Goff J et al. Cervicovaginal HIV-1 and herpes simplex virus type 2 shedding during genital ulcer diseases episodes. AIDS 21: 1569-1578, 2007
  10. Nagot N et al. Roles of clinical and subclinical reactivated Herpes Simplex Virus type 2 Infection and human immunodeficiency virus type 1 (HIV-1)–induced immunosuppression on genital and plasma HIV-1 Levels. Journal of Infectious Diseases 198:241-249, 2008
  11. Kaul R et al. The genital tract immune milieu: an important determinant of HIV susceptibility and secondary transmission. Journal of Reproductive Immunology 77: 32-40, 2008
  12. Nagot N et al. Longitudinal effect following initiation of highly active antiretroviral therapy on plasma and cervico-vaginal HIV-1 RNA among women in Burkina Faso. Sex Transm Infect (online edition), 2007
  13. Butler D et al. Correlates of HIV transmission among MSM. Fifteenth Conference on Retroviruses and Opportunistic Infections, Boston, abstract 701, 2008
This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.
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This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.