Roughly 4.4 billion people worldwide carry Helicobacter pylori, a bacterium that lives in the stomach lining. That translates to about 43% of the global population based on the most recent estimates covering 2011 through 2022. The number has been dropping, but H. pylori remains one of the most common chronic infections on Earth.
Global Prevalence by the Numbers
A large systematic review published in The Lancet Gastroenterology & Hepatology tracked H. pylori rates from 1980 to 2022. In the earliest period studied (1980 to 1990), an estimated 58% of people worldwide were infected. That figure held relatively steady through 2010, then dropped sharply to 43% between 2011 and 2022. The steepest decline occurred in the WHO African region, which historically had some of the highest rates.
The decline tracks closely with improvements in sanitation, access to clean water, and broader healthcare coverage. Countries with strong universal health systems consistently report lower infection rates.
Rates in Wealthy vs. Lower-Income Countries
Where you live is one of the strongest predictors of whether you carry H. pylori. In high-income countries, roughly 22% of the population is infected. In low- and middle-income countries, that number doubles to about 43%. Some developing regions still see rates as high as 80 to 90%.
In the United States, prevalence has historically been estimated at 35 to 40%, though that figure comes from older CDC data and current rates are likely somewhat lower given the global downward trend. The U.S. rate also varies significantly by demographic group, with higher prevalence among immigrant communities and people from lower socioeconomic backgrounds.
The gap between wealthy and poorer nations comes down to living conditions. H. pylori spreads primarily through oral contact with contaminated water, food, or saliva. Crowded households, limited access to clean water, and inadequate sewage systems all create environments where the bacterium passes easily from person to person. Intrafamilial clustering is well documented: once one household member carries H. pylori, others in the same home are at significantly higher risk.
Most Infections Start in Childhood
H. pylori is overwhelmingly a childhood infection. Most people who carry it acquired the bacterium before adulthood, often in their first few years of life. A 2021 meta-analysis found the global prevalence in children is about 32%, but this varies dramatically by age. Around 26% of children under 6 are infected. That rises to 34% in the 7-to-12 age group and 42% among teenagers aged 13 to 18.
This age pattern matters because it explains why prevalence is falling in younger generations, especially in countries where sanitation and living standards have improved within the last few decades. Children born into cleaner environments simply never pick up the infection in the first place. In many high-income countries, each successive generation has lower H. pylori rates than the one before it.
Most Carriers Never Feel Sick
One reason so many people carry H. pylori without knowing it: the vast majority never develop symptoms. Between 80 and 90% of infected individuals remain completely asymptomatic for their entire lives. The bacterium colonizes the stomach lining and persists there, sometimes for decades, without causing noticeable problems.
The remaining 10 to 20% develop conditions ranging from chronic gastritis (ongoing stomach inflammation) to peptic ulcers and, in rarer cases, stomach cancer. Why some people get sick and others don’t is still not fully understood. Differences in bacterial strains, individual immune responses, diet, and other environmental factors all appear to play a role. But for the average person carrying H. pylori, the infection is silent.
This high rate of asymptomatic carriage creates an interesting public health puzzle. Routine screening of everyone would identify billions of carriers, most of whom would never benefit from treatment. Current practice in most countries focuses on testing people who have symptoms or who fall into higher-risk categories for stomach cancer.
Why the Numbers Are Trending Down
The sharp decline since 2011 reflects real, measurable changes in how people live. Improved water treatment, better sanitation infrastructure, smaller household sizes, and wider antibiotic use have all contributed. In countries that have invested heavily in public health infrastructure, H. pylori is becoming increasingly uncommon in younger populations.
That said, the infection remains deeply entrenched in parts of Africa, South Asia, and South America where these improvements haven’t reached everyone. In some communities, more than three out of four people still carry the bacterium. The global average of 43% masks enormous regional variation, and for much of the world’s population, H. pylori remains a near-universal part of life.