About 60% of Americans harbor H. pylori bacteria, and it occurs almost universally in people who live in crowded, unsanitary conditions. Almost 25% of children in the US and about half in developing countries harbor H. pylori. A minority, however, actually go on to develop ulcers caused by the bacteria, so other factors must be present to increase susceptibility.

The bacteria may be contagious, but little is yet known about its transmission. It is possible that young adults and children with the bacteria may be infectious, but many experts do not believe adults can easily transmit H. pylori to each other. It may be spread by sewage-contaminated water or by fecal-oral transmission (caused, for instance, by touching food with hands that weren't washed after a bowel movement). Some experts postulate that the common housefly may be an important agent in transmission. 

Medical Conditions Requiring NSAIDs

Any condition that requires relief from persistent pain using NSAIDs increases the risk for ulcers. Such conditions include all forms of arthritis, chronic back pain, fibromyalgia, and many others. As with H. pylori, however, not all people who take NSAIDs develop ulcers, and other factors are involved in susceptibility. 

Factors that Increase Susceptibility to Ulcers

Genetic Factors. Genetic factors may be involved in increasing susceptibility to the effects of H. pylori. As examples, duodenal ulcers unrelated to NSAIDs seem to be two to three times more likely in relatives of people with ulcers, and identical twins have similar risks for developing ulcers. Genetic abnormalities might result in high levels of acid production, weaknesses in the mucosal layer, or production of abnormal nonprotective mucus. Inherited ulcers, however, are far less common than ulcers caused by NSAIDs or those associated with lifestyle factors that may increase a person's vulnerability to the ulcer-producing effects of H. pylori.

Caffeine, Cigarettes, and Alcohol. Coffee (both caffeinated and decaffeinated), soft drinks, and fruit juices with citric acid induce increased stomach acid production. Although no studies have proven that any of these drinks contribute to ulcers, consuming more than three cups of coffee per day may increase susceptibility to H. pylori infection.

Smoking increases acid secretion, reduces prostaglandin and bicarbonate production, and decreases mucosal blood flow. Results of studies on the actual effect of smoking on ulcers, however, are mixed. Some evidence suggests that smoking delays the healing of gastric and duodenal ulcers. One study reported that after ulcers healed, about half of nonsmokers relapsed after a year, but that all heavy smokers relapsed after three months. Other studies have found no increased risk for ulcers in smokers, and smoking does not appear to increase susceptibility to H. pylori or inhibit treatments for it. This should not give smokers any comfort, however, given the proven dangers from smoking.

Alcohol, too, has mixed reports. Some studies have shown that alcohol may actually protect against H. pylori. Drinking alcohol may, however, intensify the risk of bleeding in those who also take NSAIDs. In any case, everyone should avoid excessive use of alcohol.

Stress and Psychologic Factors. A host of studies have attempted to establish a correlation between the formation of ulcers and various types of occupations, stressful life events, lower educational or socioeconomic status, personality traits, and the ability to cope with stress, but most have found no causal relationship. Some experts believe, however, that the anecdotal relationship between stress and ulcers is so strong that attention to psychological factors is still warranted. It makes intuitive sense that stress probably plays some role in exacerbating or increasing susceptibility to peptic ulcer disease.

Blood Abnormalities. There seems to be an increased incidence of H. pylori caused ulcers in people who have Type O blood. In elderly people anemia may be a clue to the presence of an ulcer.