Vaginal Bacteria Around the World Explained

Author: Jessica Lloyd
Senior Vulvovaginal Specialist Naturopath | BHSc(N) | ISSVD, ISSWSH, BSSM, ATMS

Last reviewed: July 3, 2026

The bacteria living in your vagina are not the same the world over. Across different countries, continents and ancestral backgrounds, the mix of vaginal bacteria – your vaginal microbiome – can look strikingly different, and what counts as ‘normal’ shifts with it.¹

Here is the part that surprises people: in many populations, a diverse community with very little or no Lactobacillus is common and often causes no symptoms at all. Much of what science calls the ‘ideal’ vaginal microbiome was worked out from women in Europe and North America, so it does not automatically describe everyone.²

That matters for how we test, interpret and rebuild the vaginal microbiome – because the right protective bacteria for one person may not be the right ones for another.

Does the vaginal microbiome differ around the world?

Yes. When researchers sequence the vaginal bacteria of women from different ethnic and geographic backgrounds, they consistently find that the dominant species, and how diverse the community is, vary from group to group.¹

In broad terms, communities dominated by a single protective Lactobacillus species are more often reported in women of European and East Asian ancestry, while more diverse, mixed communities are reported more often in women of African and Hispanic ancestry.¹ These are population patterns, not rules about any individual – plenty of people sit outside the average for their background.

What are vaginal community state types?

Rather than describing every species one by one, scientists group vaginal microbiomes into five broad patterns called community state types, or CSTs. They were first mapped in a study of nearly 400 North American women and are still the standard shorthand today.¹

CST I – dominated by Lactobacillus crispatus, often considered the most stable and protective
CST II – dominated by Lactobacillus gasseri
CST III – dominated by Lactobacillus iners, a more changeable species
CST IV – diverse and low in Lactobacillus, with a mix of anaerobic bacteria such as Gardnerella and Prevotella
CST V – dominated by Lactobacillus jensenii

The original CST research found that the diverse, low-Lactobacillus CST IV was carried by roughly a third of Black and Hispanic women, compared with about one in ten white women and around one in six Asian women – making ethnicity the demographic factor most strongly linked to which community type a woman had.¹ This is part of why women of African descent are diagnosed with bacterial vaginosis more often than other women.

Is a diverse vaginal microbiome unhealthy?

Not necessarily. A diverse, low-Lactobacillus community can overlap with bacterial vaginosis (BV), but a great many people carry exactly this pattern with no symptoms, no discomfort and no infection.²

The trouble is that the ‘optimal equals L. crispatus‘ idea was built largely on European and North American cohorts. When that single template is applied to the whole planet, the naturally diverse microbiomes that are normal for millions of women can be wrongly labelled as diseased.² Researchers are increasingly arguing that we need reference data from many more populations before we can say what ‘optimal’ looks like for everyone.²

In other words, diversity on a test result is information, not an automatic diagnosis. Symptoms, history and the rest of the picture matter just as much as the species list.

A quick world tour of vaginal bacteria

The early global surveys gave us a rough map of which species tend to dominate where. It is worth holding these loosely – sampling has been patchy and heavily skewed towards wealthy Western countries – but the broad strokes are useful.²

Europe, North America and East Asia

Women of European ancestry, and women in East Asian populations such as Japan, more often show single-species Lactobacillus communities, frequently L. crispatus, L. iners, L. jensenii or L. gasseri.¹

Africa and the African diaspora

Women of African ancestry, including African American and sub-Saharan African women, more often carry diverse, mixed communities with less single-species Lactobacillus dominance.¹ In one cohort of young South African women, only about one in ten had an L. crispatus-dominant microbiome.³

The rest of the world is barely mapped

Huge parts of the globe – much of South America, South Asia, the Middle East and Indigenous communities everywhere – are hardly represented in the data at all. The honest answer for most of the world is that we simply do not have good population reference data yet.²

Why the map has so many blank spaces

The lopsided data is not an accident. Most large vaginal microbiome studies have been funded and run in wealthy, English-speaking countries, so the women sampled have mostly been of European or North American background.² When a ‘reference range’ is built almost entirely from one slice of the world’s population, it stops being a fair yardstick for everyone else.

This is why researchers are now calling for broader, more representative studies – so that ‘normal’ can be defined from the full diversity of women and people with vaginas, rather than from whoever happened to live near a research lab.²

Did you inherit your microbiome from your mother?

Partly, but not in the simple, fixed way it is often described. It is true that your background nudges the odds: in one twin study, dominance by L. crispatus was found to be modestly heritable in European American women, with host genetics explaining around a third of the variation.⁴ You can read more about how your genes help shape your vaginal microbiome in our deeper piece on the topic.

But genetics is only one ingredient. Most of what shapes your microbiome lies outside your genes: it shifts with pregnancy, contraception and the hormonal changes around menopause,⁴ as well as everyday influences like sexual activity, hygiene practices and antibiotics. The old idea that the vaginal microbiome is handed down mother-to-daughter and is ‘not external’ does not hold up: your microbiome is a moving target, influenced heavily by your body and your environment, not a fixed inheritance.

That is actually good news, because a moving target is one you can influence.

What this means for your vagina

Your community state type is not just trivia – it has real consequences for vaginal and reproductive health, which is exactly why these population differences matter.

A diverse, low-Lactobacillus microbiome is the microbial signature of BV, and it is linked to a higher risk of acquiring sexually transmitted infections. In a cohort of young South African women, those with Lactobacillus-deficient, diverse communities had roughly a four-fold higher risk of acquiring HIV, driven by inflammation in the genital tract.³

The same patterns matter in pregnancy. In a large study enriched for women of African ancestry, those who went on to deliver preterm tended to have less L. crispatus and more BV-associated bacteria early in pregnancy.⁵ Because diverse communities are more common in some populations, the burden of these outcomes is not shared equally – a fairness problem, not just a biology one.

None of this means a diverse microbiome guarantees a problem. It means the protective balance is worth understanding, especially if you have symptoms, recurrent infections or a pregnancy to protect. Keeping the vaginal environment slightly acidic, with a low vaginal pH, is one of the clearest markers of a protective community.

In our clinic, we see that while a lactobacillus-rich microbiome tends to be more protective, there is no agreed ‘perfect’ vaginal microbiome. Many groups naturally carry low lactobacilli with no symptoms at all, and for them that is normal and healthy – so we are moving away from pathologising a non-lactobacillus-rich microbiome, because that is simply not what the microbiomes of the world show us.

Frequently asked questions

Is there one ‘best’ vaginal bacteria?

L. crispatus is often described as the most stable and protective, and it tends to keep the vagina acidic.¹ But ‘best’ depends on the person, and a community without much L. crispatus is not automatically a problem.²

If my microbiome is diverse, do I have BV?

Not necessarily. Diverse, low-Lactobacillus communities overlap with BV, but many people carry this pattern with no symptoms at all.² A diagnosis takes symptoms and clinical assessment, not just a species list.

Can I change my vaginal microbiome?

To a degree, yes. Because the microbiome shifts with pregnancy, contraception and hormonal changes,⁴ and responds to everyday factors like sexual activity and antibiotics, it is not fixed at birth. That is why targeted treatment and support can help shift it.

Why do I keep getting BV when my friend never does?

Part of the answer is the community type you tend towards, which is shaped by ancestry, hormones and behaviour.¹ Two people with very different baseline microbiomes can have very different vulnerability to the same triggers.

Does my ancestry decide my vaginal health?

No. Ancestry shifts the odds of a particular community type at the population level, but it does not determine your individual microbiome or your destiny.⁴ Environment, hormones and care all play a large part.

Should the probiotic I take depend on my background?

Possibly. Since the protective species differ between people, a probiotic built around one species may not suit a microbiome that naturally runs on another.² Knowing what you actually carry, rather than guessing from your ancestry, is the more useful starting point.

What to do next

If you want to know which bacteria are actually living in your vagina – rather than guessing from averages – a comprehensive vaginal microbiome test will identify your species and give you a real starting point.

From there, it is worth understanding why species-swapping is harder than it sounds: our piece on why vaginal microbiota transplants are not working yet explains how stubborn an established community can be.

If you have symptoms or recurrent infections, you can ask Aunt Vadge’s Assistant – the chat widget in the bottom left of your screen – or book in with one of our practitioners for a personalised plan that takes your own microbiome, not a textbook average, as the starting point.

This article is general information, not a substitute for personalised medical advice. If you have symptoms or concerns, please speak with a qualified health practitioner.