Penis microbes may contribute to a common yet serious vaginal infection, study finds

(CNN) Ever heard of bacterial vaginosis? It's caused when the normal bacterial flora in the vagina go haywire, allowing "bad" bacteria to proliferate.

If the answer is no, you're not alone. Even though bacterial vaginosis, otherwise known as BV, is the most common vaginal infection in women between the ages 15 and 44, many have never heard of it.

Yet bacterial vaginosis is a serious condition, difficult to treat and eliminate. If a woman is infected during a pregnancy, vaginosis can cause the baby to be born prematurely or with a low birth weight.

What's more, BV also leaves women at higher risk for contracting HIV or other sexually transmitted infections such as chlamydia and gonorrhea -- diseases which can trigger pelvic inflammatory disease and dash any hopes of having children.

Vaginosis affects 20% of women worldwide, with more than 21 million of those in the United States, studies have shown. Yet only some 4 million women in the US currently receive treatments, which are often ineffective.

"Antibiotic treatment of BV has limited long-term success, with up to 50% of women having recurrence within 6 months, so we need more effective approaches to treatment," said Supriya Mehta, an epidemiologist at University of Illinois at Chicago.

Despite the significant dangers, BV doesn't have a known cause, according to the US Centers for Disease Control and Prevention. It appears to happen to women with new or multiple sex partners, as well as to women who douche, which can upset the balance of bacteria in the vagina.

Now a new study finds that men seem to play a key role in the transmission of bacterial vaginosis.

Not only did researchers find BV-related bacteria in the microbes of male penises, the existence of the bacteria was highly predictive of the infection in the female sex partner.

"Male sex partner treatment may be a new strategy," said Mehta, a first author of the study, published Tuesday in the journal Frontiers in Cellular and Infection Microbiology.

"I would like for clinicians, researchers, and the public to be inclusive of male sex partners in their efforts to improve women's reproductive health," he said in a statement. "Not to place directionality or blame on one partner or another, but to increase the options and opportunity for improved reproductive health, and hopefully reduce stigma from BV."

A direct link

The study followed 168 Kenyan heterosexual couples over the course of a year. None of the women had bacterial vaginosis at the start of the study; by the end of the year, more than 31% of the women developed the condition.

While each man's penile microbes were different, there was a direct correlation between each man's microbiome and the later occurrence of bacterial vaginosis in his female partner.

Using a computer analysis, researchers were able to identify 10 bacteria in the men's penises that accurately predicted the occurrence of BV in their partners.

Signs of bacterial vaginosis often mimic other vaginal conditions, such as a yeast infection. They include vaginal pain, itching, or burning as well as burning during urination; a thin, gray or white vaginal discharge; and a strong fish-like odor, especially after sex.

If there are symptoms at all. Many women can have mild or even no signs of bacterial vaginosis, thus allowing it go untreated and continue to damage the female reproductive tract.

Experts call for an increased awareness of the existence of BV, saying women should be educated on the signs, symptoms and risks of bacterial vaginosis. In addition, health care providers should do more to test for the condition during gynecological checkups.