HIV: Common women's condition thought to raise risk
Updated 12:06 pm, Wednesday, July 4, 2012
The bacteria that colonize the human body can boost the immune system, aid with digestion and fend off disease-causing bugs. But when that colony is off-balance, it can cause a cascade of health problems that scientists are just beginning to understand.
One of the most notable examples of that cascade effect may be bacterial vaginosis, a common and mostly asymptomatic condition marked by an infestation of abnormal flora in the vagina - and a condition that could be a major culprit in the global HIV/AIDS epidemic.
Studies have shown that women with bacterial vaginosis are 60 percent more likely to be infected with HIV than women with healthy vaginal flora, and once they're infected, they release more of the virus.
Now a UCSF study, published last month, has found that women with bacterial vaginosis are three times more likely to pass HIV to their partner than HIV-infected women with healthy flora.
Because bacterial vaginosis is very common - it affects roughly 50 percent of women in some regions of the globe - treating the condition could significantly cut the spread of HIV worldwide, said Dr. Craig Cohen, lead author of the study and a professor obstetrics, gynecology and reproductive sciences at UCSF.
"It's such a common condition that potentially a lot of HIV transmission can be related" to bacterial vaginosis, he said. "But we don't have a good way of treating bacterial vaginosis and normalizing the vaginal flora. That's a really big problem."
Bacterial vaginosis is especially common among black women in Africa and in the United States, and women in both parts of the world bear the brunt of new cases of HIV infection. Many women with bacterial vaginosis don't even realize there's anything wrong because their vaginal flora has always been abnormal, Cohen said. Symptoms of bacterial vaginosis include a thin discharge and unpleasant smell, but many women are asymptomatic.
Male partners at risk
Cohen's study, published in the journal PLoS Medicine, looked at 2,236 couples in seven African countries. In all of the couples, the woman was HIV-positive and the man was HIV-negative. Men whose partner tested positive for bacterial vaginosis at least once during the two-year study period were more than three times as likely to contract HIV than men whose partner had healthy vaginal flora.
It's unclear why bacterial vaginosis is associated with an increased risk of developing and transmitting HIV. The condition is defined by an absence of certain healthy flora and an overabundance of harmful bacteria. It could be that the bacterial imbalance increases the activity of cells that are especially susceptible to HIV, Cohen said.
Women would be at greater risk of developing HIV because of that bacterial imbalance. Men may also be at risk because partners sometimes share the bacterial colonies in their genitals when they have sex.
Cohen said he hopes that the new research will spawn further study into treating bacterial vaginosis. The condition can be temporarily cured with antibiotics to kill off the unhealthy bacteria, but recurrences are common. Ideally, he said, scientists will take a greater interest in the vaginal microbiome in general.
"People don't consider bacterial vaginosis a healthy, natural state. But if you have half the population of women with BV, it begs the question of what's normal," Cohen said. "We definitely need increased research in this area."