Experts suggest there are likely variations in what is considered a “healthy” vaginal microbiome. (Image credit: nopparit via Getty Images)
Researchers aim to create a complete map of the vagina, an atlas that describes the diversity of microorganisms that live there.
These microorganisms are collectively known as the vaginal microbiome and include bacteria, fungi, protozoa called archaea, and viruses, although viruses are not technically considered “living.” Changes in the abundance of these microbes, especially bacteria, have been linked to a variety of health conditions, including pregnancy complications such as preterm birth; chronic diseases such as endometriosis; and infections, including urinary tract infections (UTIs) and human papillomavirus (HPV).
The relationship between the vaginal microbiome and these conditions is not yet fully understood. Meanwhile, mapping work is complicated by the fact that vaginal microbiome studies have mostly been conducted in certain highly developed countries. This has biased the results toward certain population groups, some scientists say.
In a commentary published Thursday (Feb. 6) in the journal Trends in Microbiology, a group of more than a dozen researchers concluded that we currently don't know what a “healthy” vaginal microbiome is for different demographics around the world.
“More research is needed on the function and diversity of the vaginal microbiota in different parts of the world,” the researchers write. “We are still trying to understand which bacteria should be considered pathogenic and which have more protective functions.”
For example, a landmark study published in 2010 analyzed nearly 400 women in North America and identified five distinct profiles that a healthy vaginal microbiome can have. Each is defined as being dominated by a specific type of bacteria, such as Lactobacillus crispatus or Lactobacillus gasseri.
Scientists have proposed additional categories over the years, again based on North American samples, but when it comes to other geographic regions, these categories don’t always apply. A 2023 study looked at thousands of healthy women in Belgium and found that more than 10% of them didn’t fit into the five most established categories.
The Belgian study was carried out by the Isala group at the University of Antwerp. Named after Isala Van Diest, the first female doctor in Belgium, the project has since expanded into a global research initiative called the Isala Sisterhood Consortium. Isala projects have been launched in countries including Peru, Cameroon, Nigeria, Spain and the United States, with more planned for the near future. The authors of the new opinion piece contribute to the Isala research.
Potential benefits of these studies could include new treatments for bacterial vaginosis (BV), which is generally defined as a decrease in Lactobacillus bacteria in the vagina combined with an overgrowth of other anaerobic bacteria. BV does not always cause noticeable symptoms, but it is associated with an increased risk of other health problems, including sexually transmitted infections such as HIV. BV is usually treated with antibiotics, but often returns after this treatment.
The authors suggested that with a better understanding of the vaginal microbiome, scientists could develop ways to “directly modulate” it, perhaps by introducing “protective” bacteria back into the microbiome as they are lost. Notably, there is also no universal standard for diagnosing BV, and it is unclear whether it is possible to unambiguously identify BV worldwide.
“The persistent presentation of lactobacilli as the gold standard for optimal vaginal health needs to be carefully (re)evaluated in light of the objective perspective of global diversity,” the authors write.
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