Women with bacterial vaginosis are much more likely to transmit HIV to males than other females, researchers from the University of California, San Francisco, reported in PLoS Medicine. The risk is three times greater, the authors added.

Bacterial vaginosis (BV), also known as vaginal bacteriosis, is a condition in which the vagina's normal balance of naturally occurring microorganisms in the vaginal flora has changed, so that the 'good' bacteria are reduced and the harmful bacteria increase. About 50% of all females with bacterial vaginosis are asymptomatic - they have no symptoms.

If BV symptoms do appear, they may include a watery and thin vaginal discharge, the discharge can become gray or white, and it may have a strong (fishy) smell. Less commonly, some women may experience a durning sensation when urinating, and itching around the outside of the vagina.

Bacterial vaginosis raises the risk of acquiring STIs

Women with bacterial vaginosis are more susceptible to acquiring sexually transmitted infections (STIs), including HIV and have a higher risk of preterm delivery. HIV-positive women with bacterial vaginosis potentially have higher HIV levels, and their cervix and vagina may shed greater amounts of the virus.

Lead author, Craig R. Cohen, MD, MPH, professor of obstetrics, gynecology and reproductive sciences at UCSF wrote:

"Previous research has shown that bacterial vaginosis can increase a women's risk of becoming infected with HIV as much as sixty percent. Our study is the first to show that the risk of transmitting HIV is also elevated.

Our findings point to the need for additional research to improve the diagnosis and treatment of bacterial vaginosis, which is extremely common in sub-Saharan Africa, the region of the globe with the highest burden of HIV."

They examined the link between bacterial vaginosis and female-to-male HIV transmission risk. The prospective study involved 2,236 HIV- positive women and their uninfected male partners from seven African countries.

After the scientists had adjusted the findings for variables, such as sexual behavior, socio-demographic factors, male circumcision, sexually transmitted infections, pregnancy and HIV levels in the HIV-positive women's blood, they discovered that bacterial vaginosis was linked to a considerably higher risk of female-to-male HIV transmission.

Cohen explained:

"We looked at the increased shedding of HIV in the genital tract, but that was not sufficient to explain the increased risk of female-to-male HIV transmission. It is also possible that bacterial vaginosis causes inflammation and that could be a factor. We don't really understand the relationship between vaginal flora and inflammation.

We think it's likely that the sharing of genital tract microbiota between women and men may be implicated as a cause of the transmission risk. The interrelationship of the sharing of flora remains poorly understood and is an important avenue for future research."

Cohen concluded that more studies are required to gain a better understanding of the vaginal flora's role. However, developing more treatments for bacterial vaginosis, such as improved drugs and probiotics would be a considerable step forward towards improving women's health in general, but it would also be beneficial in helping to decrease the number of HIV infections and the risk of transmission.

Written by Petra Rattue