Helicobacter pylori and gastroduodenal disease: pathogenesis and host-parasite interaction.

Helicobacter pylori has been shown to be the cause of chronic active gastritis and the evidence that it is involved in the development of peptic ulcer disease and gastric cancer is compelling. Narrow host range, tissue specificity, and chronic inflammation are hallmarks of infection. The study of virulence determinants has just begun but it seems likely that urease, adhesins, cytotoxins, and mediators of inflammation will prove to be important.