H. pylori infects roughly 38.5% of the global population, making it one of the most widespread bacterial infections in the world. That means nearly 4 in 10 people carry this stomach bacterium, though rates vary dramatically depending on where you live, your age, and your socioeconomic background. Perhaps most striking: 80 to 90% of infected people never develop symptoms.
Global Prevalence by Region
H. pylori is far from evenly distributed. Western Africa has the highest estimated prevalence at 71.8%, followed closely by Central Asia at 70.6% and Central America at 60.9%. On the other end, Oceania has the lowest rate at just 16.4%, with Northern Africa at 22.2% and Western Europe at 25.4%.
The pattern tracks closely with sanitation infrastructure and living conditions. In countries with untreated water, crowded housing, and limited hygiene resources, infection rates climb steeply. This gap helps explain why a child growing up in rural West Africa faces a fundamentally different risk than one in suburban Australia.
The good news is that global rates are falling. Between 1980 and 1990, an estimated 58.2% of the world’s population was infected. By 2011 to 2022, that figure had dropped to 43.1%. Improvements in water treatment, sanitation, and smaller household sizes in many parts of the world are driving the decline.
How Common H. Pylori Is in the United States
About one in three American adults (32.7%) tests positive for H. pylori antibodies. That’s lower than the global average, but the number hides significant variation across age groups and ethnic backgrounds.
Age is one of the strongest predictors. Only about 16.7% of adults in their twenties carry the infection, while 56.9% of those over 70 do. This doesn’t necessarily mean older people are catching it later in life. Most infections are acquired in childhood, so higher rates in older adults largely reflect the less sanitary conditions they grew up in decades ago.
Ethnicity and socioeconomic factors also play a major role. In the U.S., prevalence among Mexican Americans is 57.9% and among non-Hispanic Black adults is 51.1%, compared to 26.9% among non-Hispanic white adults. Much of this disparity is explained by differences in income, household crowding, education level, and whether someone was born outside the United States. After accounting for those factors, the gap narrows considerably, though it doesn’t disappear entirely.
How It Spreads
H. pylori passes from person to person primarily through saliva and through fecal contamination of food or water. This means close household contact is the main route of transmission, not casual interactions. Parents and siblings are the most common source of infection for children, which is why most people who carry H. pylori picked it up before age 10.
You won’t catch it from a handshake or sitting next to someone on a bus. The bacteria need a more direct path to reach your stomach. Sharing utensils, drinking untreated water, or living in tight quarters with an infected family member are the scenarios that matter most.
Most Infections Cause No Symptoms
This is the part that surprises most people: somewhere between 80 and 90% of those carrying H. pylori will never know it. The bacteria colonize the stomach lining and can live there for decades without causing noticeable problems. Only 10 to 20% of infected individuals develop serious gastric diseases like ulcers or chronic stomach inflammation.
Why some people get sick while others don’t remains an open question. It likely involves a combination of the specific bacterial strain, the person’s immune response, diet, and other lifestyle factors. But the bottom line is that carrying H. pylori is not a guarantee of illness.
Health Risks for the Minority Who Get Sick
When H. pylori does cause problems, those problems can be serious. The bacterium damages the protective mucous lining of the stomach, leading to inflammation and, in some cases, ulcers. It’s also strongly linked to stomach cancer: people with H. pylori are about six times more likely to develop stomach cancer than uninfected people, and roughly 90% of stomach cancer cases are associated with the infection.
That six-fold increase sounds alarming, but context matters. Stomach cancer is relatively rare in the U.S. and other high-income countries. A six-fold increase in a small baseline risk still leaves most infected people at low absolute risk. Still, H. pylori is classified as a carcinogen, and eradication treatment is recommended for people who test positive and have additional risk factors like a family history of stomach cancer.
How It’s Diagnosed
If you’re wondering whether you have H. pylori, three noninvasive tests are commonly used, and they differ in accuracy.
- Urea breath test: The most accurate option. You drink a solution and breathe into a collection bag. The bacteria produce a specific gas that the test detects. Sensitivity is around 92 to 94%, meaning it catches the infection in the vast majority of cases.
- Blood test (serology): Checks for antibodies to H. pylori. It’s simpler but less precise, with a sensitivity of about 84%. One drawback is that antibodies can linger for months or years after the infection is gone, so a positive result doesn’t always mean you’re currently infected.
- Stool antigen test: Detects bacterial proteins in a stool sample, with a sensitivity of about 83%. It’s useful for confirming active infection and for checking whether treatment worked.
For any of these tests, accuracy improves when you haven’t recently taken antibiotics or acid-reducing medications, which can temporarily suppress the bacteria and produce a false negative.
Treatment Success Rates
H. pylori is curable with antibiotics, though it’s not always a one-and-done process. Standard treatment combines two or three antibiotics with an acid-suppressing medication, taken for 10 to 14 days. The overall success rate for standard therapy is about 75%, which means roughly one in four people need a second round.
A more intensive regimen that adds a bismuth compound (the active ingredient in Pepto-Bismol) pushes success rates to about 90%. Newer treatment approaches using a different type of acid suppressor have shown particular promise against antibiotic-resistant strains, nearly doubling eradication rates compared to standard therapy when the bacteria are resistant to one of the commonly used antibiotics.
Antibiotic resistance is a growing concern worldwide and one of the main reasons first-line treatment fails. If your initial course doesn’t clear the infection, your doctor will typically switch to a different antibiotic combination for the second attempt.