Issue: August 2011
August 01, 2011
2 min read

Bacterial vaginosis linked to female-to-male HIV-1 transmission

Issue: August 2011
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Bacterial vaginosis in HIV-1 infected females was associated with the risk for transmission among male partners. Therefore, Craig R. Cohen, MD, MPH, and colleagues suggest that normalization of vaginal flora in HIV-1 infected women may decrease virus transmission.

“While bacterial vaginosis increases HIV-1 shedding from the female genital tract, its impact on HIV-1 transmission to male partners has not been assessed,” according to the study abstract presented at the 6th IAS Conference on HIV Pathogenesis, Treatment and Prevention in Rome.

In the prospective study, Cohen, of the University of California, San Francisco, and colleagues measured the effect of bacterial vaginosis compared with normal vaginal flora and the risk for female-to-male HIV-1 transmission.

Craig R. Cohen, MD, MPH
Craig R. Cohen, MD, MPH

The cohort included 2,236 HIV-1 seronegative men with an HIV-1 seropositive female partner recruited from seven sub-Saharan African countries. The researchers used Nugent’s criteria to collect and evaluate vaginal Gram’s stains every 3 months, for up to 2 years.

Compared with an HIV-1 incidence of 2.87/100 person-years (HR=3.09; 95% CI, 1.58-6.06) among men whose female partners had bacterial vaginosis 3 months before detecting HIV-1 seroconversion, HIV-1 incidence was 0.88/100 person-years in men whose female partners had normal vaginal flora.

After adjusting for socio-demographic factors, sexual behavior, male circumcision, sexually transmitted infections at enrollment, and pregnancy and plasma HIV-1 RNA in female partners, researchers found that men whose female partner had bacterial vaginosis 3 months before identifying HIV-1 seroconversion (HR=2.83; 95%CI, 1.29-6.22) and at the same visit (HR=3.64; 95% CI, 1.68-7.90) had an increased incidence of HIV-1 compared with men whose female partners had normal vaginal flora.

For more information:

  • Cohen CR. # MOAC0202. Presented at: The 6th IAS Conference on HIV Pathogenesis, Treatment and Prevention; Rome; July 17-20, 2011.


There are increasingly convincing data that the state of vaginal microenvironment is very important in determining the risk of HIV heterosexual transmission from men to women. Several investigators have established that bacterial vaginosis (BV) increases the risk HIV infection by ~1.6-fold. The Rakai Community Cohort Study found that pregnancy conferred a 2.1-fold increased risk of HIV infection. Data on hormonal contraceptives have been inconsistent, but have suggested that progesterone dominant contraception may increase the rate of HIV acquisition. Studies focusing on post-menopausal women with atrophic vaginitis have not been done. For unclear reasons, grants requesting funds for such work have not been awarded or even scored. However, observational data and the physiology of the vaginal epithelium again suggest that post-menopausal women are at increased risk of HIV acquisition.

Very few studies which focus on the vaginal microenvironment and female to male HIV transmission have been performed. At the International AIDS Society meeting in Rome, Craig R. Cohen presented data from a study, which measured the impact of BV on female-to-male HIV transmission. Over 2,200 HIV negative men and their HIV positive female partners were followed for an average of over 5 years. Recent BV in the female partner increased the rate of HIV transmission by 3-fold. The mechanism for this increased rate of transmission is not understood, since the effect of BV on HIV vaginal shedding was modest. Monitoring the vaginal flora of HIV infected women in monogamous relationships with uninfected men and treating those with BV may have a significant effect on HIV transmission. The recent data from HPTN 052 show that ART is very effective at preventing HIV transmission in this same scenario. Monitoring and treating HIV positive women for BV may be more easily achieved in the short run than providing HIV treatment in resource poor settings.

– Stephen Smith, MD

Infectious Disease News Editorial Board member

Disclosure: Dr. Smith reports no relevant financial disclosures.

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