Risk Factors

About 25 million American are expected to have peptic ulcers at some point in their lives. Peptic ulcer disease affects all age groups but is rare in children. Men have twice the risk for ulcers as women. The risk for duodenal ulcers tends to rise at around age 25 and continues until age 75; gastric ulcers peak in people between the ages of 55 and 65.

Peptic ulcers are less common than they once were. Research suggests that ulcer rates have even declined in areas with widespread H. pylori infection. The increased use of proton pump inhibitor drugs may be responsible for this trend.

Risk Factors for H. pylori

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H. pylori grows and colonizes only in the intestinal tracts of primates and in no other animals. The bacteria is most likely transmitted directly from person to person. Still, little is yet known about its transmission.

Who is Infected with H. Pylori? About half of the world's adults are infected with H. pylori. The bacteria, however, are nearly always acquired during childhood and persist throughout life if not treated. The prevalence in children ranges from under 10% to over 80%, depending on where they live. The highest infection rates (3% to 10%) are in developing countries and the lowest (0.5%) are in industrialized nations, where the rates continue to decline. Even within industrialized countries, however, the infection rates in regions that have crowded unsanitary conditions are equal to those in developing countries.

How Does the Bacteria Pass from Person to Person? It is not entirely clear how the bacteria is transmitted. A 2001 Swedish study, for example, did not find that infected students posed any risk for their classmates. Transmission within families may be the most important route for H. pylori. A 2002 study reported that spouses of people with peptic ulcers are at significantly higher risk for ulcers, suggesting that the bacteria may be transmitted from intimate contact. Some evidence suggests that it is transmissible during gastrointestinal tract illness, particularly when vomiting occurs. The bacteria also may be passed in stools. Since H. pylori can live in water, but not apparently in food, then the bacteria may also be spread by sewage-contaminated water.