Two Australians have won the 2005 Nobel medicine prize for discovering the bacterium behind stomach inflammation and ulcers.
The Nobel Assembly of Stockholm's Karolinska Institute said in awarding the 10 million crown (€1.1 million) prize to Barry Marshall and Robin Warren that the pair had gone against established dogma that ulcers were caused by lifestyle and stress.
The medical researchers made the "remarkable and unexpected discovery" in 1982 that the stomach inflammation known as gastritis and ulceration of the stomach and duodenum known as peptic ulcer disease are caused by the bacterium Helicobacter pylori.
"Thanks to the pioneering discovery by Marshall and Warren, peptic ulcer disease is no longer a chronic, frequently disabling condition, but a disease that can be cured by a short regimen of antibiotics and acid secretion inhibitors," the assembly said in a statement.
Staffan Normark, a member of the Nobel Assembly, told journalists that Mr Marshall had even tested the hypothesis on himself, by drinking a culture of Helicobacter pylori.
He contracted a severe case of gastritis from drinking the culture but it disappeared fairly quickly, which was "a bit disappointing", said Curt Einarsson, professor of gastroenterology at Karolinska University Hospital.
Mr Warren, (68) and Mr Marshall, (54) share the prize, which was founded in the will of the Swedish inventor of dynamite, Alfred Nobel , in 1895.
They found that the bacterium colonises the stomach and was present in almost all patients with gastric inflammation, duodenal ulcer or gastric ulcer.
Drugs companies looked closely at the Australians' work when developing treatments for ulcers. The market for stomach treatments is worth around $20 billion a year, said a spokesman for Anglo-Swedish group AstraZeneca.
Other manufacturers are Abbott Laboratories of the United States and Japan's Takeda, which have a joint venture. The bacterium causes more than 90 per cent of duodenal ulcers and up to 80 per cent of gastric ulcers.
About two-thirds of the world's population is infected with H pylori, but most people never suffer any symptoms. It also predisposes people to stomach cancer, which is the second most common cause of cancer death.