Timeline of peptic ulcer disease and Helicobacter pylori

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This is a timeline of the events relating to the discovery that peptic ulcer disease and some cancers are caused by "H. pylori".</onlyinclude> In 2005, Barry Marshall and Robin Warren were awarded the Nobel Prize in Physiology or Medicine for their discovery that peptic ulcer disease (PUD) was primarily caused by "Helicobacter pylori", a bacterium with affinity for acidic environments, such as the stomach. As a result, PUD that is associated with "H. pylori" is currently treated with antibiotics used to eradicate the infection. For decades prior to their discovery, it was widely believed that PUD was caused by excess acid in the stomach. During this time, acid control was the primary method of treatment for PUD, to only partial success. Among other effects, it is now known that acid suppression alters the stomach milieu to make it less amenable to "H. pylori" infection.
Background.
Before the 1950s, there were many microbiological descriptions of bacteria in the stomach and in gastric acid secretions, lending credence to both the infective theory and the hyperacidity theory as being causes of peptic ulcer disease. A single study, conducted in 1954, did not find evidence of bacteria on biopsies of the stomach stained traditionally; this effectively established the acid theory as dogma. This paradigm was altered when Warren and Marshall effectively proved Koch's postulates for causation of PUD by "H. pylori" through a series of experiments in the 1980s; however, an extensive effort was required to convince the medical community of the relevance of their work. Now, all major gastrointestinal societies agree that "H. pylori" is the primary nondrug cause of PUD worldwide, and advocate its eradication as essential to treatment of gastric and duodenal ulcers. Additionally, "H. pylori" has been associated with lymphomas and adenocarcinomas of the stomach, and has been classified by the World Health Organization as a carcinogen. Advances in molecular biology in the late 20th century led to the sequencing of the "H. pylori" genome, resulting in a better understanding of virulence factors responsible for its colonization and infection, on the DNA level. 
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Pre-20th century.
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