Natural history of Helicobacter pylori infection

Abstract

This report describes the modalities of chronic gastritis induced by Helicobacter pylori infection in different populations. The full gamut of lesions representing the precancerous cascade is very prevalent in populations of low socioeconomic background experiencing very high gastric cancer risk, as seen in the Latin American Andes Mountains. In populations of high socioeconomic standards and high cancer risk, such as Japan and Korea, the precancerous cascade predominates and "early" cancers are also diagnosed frequently. Some reports describe frequent corpus atrophy, not prominent in the former group. The so-called African enigma is seen in populations of low socioeconomic standards, usually living at low altitudes, with high prevalence of infection but low frequency of cancer and precancerous lesions. In populations in transition from high to low cancer risk, duodenal ulcer and antral non-atrophic gastritis are frequently seen. In affluent societies at low risk of cancer, such as Western Europe, Australia and North America, mild non-atrophic gastritis associated with low virulence Helicobacter pylori genotypes predominate. The varied phenotypes of gastritis may reflect secular changes in the ecology of our species.

Figure 1

Schematic representation of the clinical outcomes following H. pylori infection.

Figure 2

Histological section of gastric antral mucosa infected with H. pylori. Abundant microorganisms are observed in the luminal surface and attached to the epithelium. (Modified Steiner silver stain)

Figure 3

Multifocal atrophic gastritis in a Colombian subject residing in a high gastric cancer risk area, infected with a cagA-positive vacA s1m1 H. pylori strain. Marked inflammatory infiltrate and loss of glandular structures are observed. (H&E stain)

Figure 4

Multifocal atrophic gastritis with intestinal metaplasia (colonic type) in a Colombian subject residing in a high gastric cancer risk area, infected with a cagA-positive vacA s1m1 H. pylori strain. Normal glands seen on the left side display neutral mucins (magenta). Metaplastic epithelium, on the right side, displays acidic mucins (purple) in the goblet cells and neutral mucins in the columnar cells. (AB-PAS stain)

Figure 5

Non-atrophic chronic gastritis in a subject residing in a low gastric cancer risk area, infected with a cagA-negative vacA s2m2 H. pylori strain. Mild to moderate mononuclear infiltrate and well preserved glandular structures are observed. (H&E stain)