This Common STI Can Change Your Vagina’s Bacteria Balance, A New Study Says

HPV, or the human papilloma virus, is an incredibly common sexually transmitted infection (STI); it's estimated that 14 million people contract HPV in the U.S. alone every year, according to the American Sexual Health Association. While there's now a vaccine, Gardasil, that can protect you from strains of HPV linked with cervical cancer, many other strains cause symptoms like genital warts — or they may cause no symptoms at all. Now, a new study published in Frontiers In Cellular & Infection Microbiology has illuminated how a low-risk variety of HPV can change our vaginal microbiome.

The vagina is home to many kinds of bacteria and other microscopic life, otherwise known as a microbiome, and that's perfectly fine; a balanced microbiome is a key element of vaginal health. Unbalanced microbiomes can cause things like yeast infections, where yeast that naturally occurs in the microbiome overgrows and causes unpleasant symptoms. (This is why doctors don't recommend douching, as it creates imbalances in the natural flora of the vagina and can induce infection.)

There are up to 40 different types of HPV that can be spread by sexual contact, according to the Centers for Disease Control & Prevention, and a large quantity of them are completely asymptomatic. Just because they don't display symptoms, though, doesn't mean they haven't caused any changes down there.

The team behind the recent study looked at 62 different samples of vaginal microbiota, some of which had a low-risk HPV infection. Low-risk HPV strains, like HPV 7 and HPV 11, are classified as benign because they aren't linked to illnesses like cervical cancer, though they can cause things like genital warts. The women with low-risk HPV infections in the study all had a condition known as condyloma acuminatum, or a benign kind of genital warts.

Dr. Nick Wheelhouse, a microbiologist at Edinburgh Napier University who reviewed the study for Frontiers, tells Bustle that it was this focus on low-risk HPV types that made the study intriguing. "They focused on the low-grade HPV and found something very similar to what people found with high-grade HPV, which is where science tends to focus because of the cancer-causing implications," he tells Bustle. "In the case of low-risk HPV, we're really just talking genital warts."

The study sequenced the genomes of the specimens, and found that vaginas with low-risk HPV infections had very different microbiomes than those that didn't. People with low-risk HPV had lower levels of Firmicutes, one of the most common bacteria in the vagina and the gut, but overall their levels of other bacteria were higher. Actinobacteria, which show up a lot on human skin and in female urinary tracts, were more common, as were Proteobacteria, a hugely diverse group of bacteria that includes healthy members and nasties like E.coli, and Fusobacteria phyla, which often appears in the mouth, intestines and genitals. Higher levels of Gardnerella, the bacteria that cause bacterial vaginosis, Bifidobacterium, which help with intestinal digestion of fibers, and Burkholderia, which can be beneficial or can seriously damage human health, were also found, plus several other varieties. People with low-risk HPV also had a greater diversity of bacteria in their vaginas.

A lot of the bacteria the study identified were in minuscule quantities, but the authors warn that tiny quantities can still be powerful in microbiomes. "Many studies of human microecology have found that the changes in the abundance of many low-abundance species have an important influence on human health and disease progress," they write in the study.

If you have HPV, having a healthy microbiome in your vagina is important when it comes to managing the condition. "In the last few years, there have been several observational studies which suggest that a healthy microbiome in the vagina promotes the clearance of HPV infections, including those variants which are associated with the development of cervical cancer," Dr. G. Thomas Ruiz MD, OB/GYN Lead at MemorialCare Orange Coast Medical Center, tells Bustle. This also applies to people who don't have HPV, because it may help them clear the virus more swiftly. "Keeping it simple, if a woman is able to maintain a normal microbiome when exposed to HPV, she should be better able to clear the infection," Dr. Ruiz says.

The study also identified something else troubling. A lot of people who had low-risk HPV in the study also had chlamydia and mycoplasma genitalium, a kind of bacteria that can cause an STI. People who have HPV and other illnesses at the same time can find that genital warts recur more often and are harder to cure, and the scientists behind the study point out that often people with multiple STIs may not know they have more than one, and so don't get proper treatment. If you have genital warts, they recommend that you have an STI test to detect any other illnesses, as treating them all will help prevent warts from recurring.

However, over the longer term, this may prove to be less of an issue for people with vaginas. "The HPV genotypes here are covered by Gardasil," Dr. Wheelhouse tells Bustle. In countries where the vaccine is commonly taken, he says "these forms are probably dying out a little bit." Right now, they continue to flourish, but over time Gardasil may make these low-grade types less and less of an issue.

The study doesn't provide a magic bullet for dealing with these issues. "Work needs to continue on the relationship between a healthy vaginal microbial environment and the clearing of the HPV virus," Dr. Ruiz tells Bustle. However, this is only the beginning. "This study pretty much says "This is the start, and this is going to lead to potential further work in this area,"" says Dr. Wheelhouse. Expect more interest in low-risk HPV in the future — and more insight into how it changes the body.