In 1982, two Australian scientists discovered that a certain bacterium, Helicobacter pylori, was a common cause of persistent stomach inflammation and stomach ulcers. This realization revolutionized ulcer treatment.
While fairly common, this infection usually causes no symptoms, but it can sometimes lead to ulcers in the stomach or the very first part of the small intestine (duodenum), and to certain types of stomach cancer. There is also evidence linking H. pylori infection to other conditions like iron-deficiency anemia and vitamin B12 deficiency. The bacteria are thought to spread through contaminated water, vomit, or feces. Most infections are acquired in childhood and often within families, especially in developing countries.