History of Helicobacter pylori, duodenal ulcer, gastric ulcer and gastric cancer

Table 1 Possibilities why duodenal ulcer seemed to appear in Europe at the end of the 19^th century

Change in prevalence of the infection (e.g., acquisition of a new pathogen or increased prevalence of existing pathogen)

Change in the age of acquisition of the infection resulting in different clinical manifestations

Change in virulence of Helicobacter pylori (H. pylori)

Change in host-H. pylori interaction (e.g., resulting in change in the intensity of inflammation)

Change in the host-bacterial-environmental interactions such that the host is better able, or less able to defend against the infection or the effects of the infection as reflected in the pattern and extent of gastritis/atrophy