As H. pylori has been disappearing, peptic ulcer disease and noncardia gastric cancers have predictably been decreasing. However, maladies such as gastroesophageal reflux disease, Barrett esophagus, and adenocarcinomas of the lower esophagus and gastric cardia have been dramatically and progressively increasing. In white men in the United States, adenocarcinoma has surpassed squamous cell carcinomas as the main type of esophageal tumor, and among gastric tumors, cancers at the cardia have become nearly as frequent as those located more distally. If these findings are confirmed, as I believe they will be, then the clinical evaluation of H. pylori will become increasingly complex. An important question is whether we should refer to our interaction with H. pylori as colonization or as infection.
Infection indicates a relation that is harmful to the host.
Colonization is a broader term that indicates a persistent interaction without qualifying whether or not it is harmful. Favoring the concept of infection for H. pylori is the presence of a tissue response, and the fact that the organism's presence increases risk for disease. I believe it likely that the tissue response to H. pylori in the stomach represents a parallel process, but one that we are calling chronic active gastritis . The interactions of H. pylori and humans have many parallels with those for these organisms. For these reasons, the broader term, colonization, appears most appropriate for describing the fundamental interaction of H. pylori and humans.