Clinical Manifestations

The initial phases of H.pylori infection elicit an acute mucosal inflammatory response whose clinical manifestations may include epigastric pain, nausea, and vomiting. Such symptoms are uncommon and are usually short-lived. Because patients rarely undergo endoscopic procedures in the early stages of H.pylori infection, information regarding clinical aspects is limited. However, well-documented case reports allowed a glimpse into the early aspects of the infection and of iatrogenic H.pylori infection resulting from the use of inadequately disinfected endoscopes. Most of these patients had multiple antral ulcers or erosions, whereas others had a predominance of hemorrhagic lesions; both their endoscopic and histopathological findings are virtually identical to those reported in subjects from human ingestion studies and in patients with epidemic gastritis and achlorhydria, a condition described before H.pylori was discovered and later found to be a manifestation of acute H.pylori infection.

In patients with uncomplicated chronic H.pylori gastritis, the prevalence of dyspepsia is probably no greater than in uninfected persons, and among patients with nonulcer dyspepsia, the prevalence of infected and noninfected persons is similar. Furthermore, cure of H.pylori in patients with nonulcer dyspepsia has not been shown conclusively to improve the dyspeptic symptoms, although the reasons for this apparent lack of effect continue to be debated. Even with its unclear relation to dyspepsia, H.pylori infection has been estimated to be responsible for approximately 5% of gastrointestinal ailments in the community, and patients with H.pylori gastritis are at increased risk of duodenal and gastric ulcer, gastric cancer, and lymphoma.

Epidemiology

In many developing countries, the prevalence of H.pylori in adults is close to 90%, with very high percentages of infected children, suggesting exposure to the bacteria early in life. In established industrialized countries (Western Europe, United States, Canada, and Australia), exposure occurs later, resulting in minimal percentages of infected children (<1% in Swedish and Danish schools in the year 2000) and low percentages of infected adults (~30% by age 50 years). Although the mechanisms of transmission remain poorly understood, improved socioeconomic conditions result in a decreased prevalence of H.pylori, as vividly illustrated by historical data from Finland, Sweden, and Japan. Furthermore, innumerable people receive amoxicillin, which, used alone, may cure approximately 10% of H.pylori infections, as well as other antibiotics for the treatment of respiratory and other infections. Among H.pylori–infected patients undergoing such therapies, a small but cumulatively significant percentage is cured. Finally, it is likely that targeted anti– H.pylori treatment in individual patients reduces transmission in the community and ultimately may contribute to thedecreased prevalence of the infection in the population.

Дата добавления: 2015-11-14