The Australian duo of Barry J Marshall and J Robin Warren were Monday awarded the Nobel Prize for Medicine.
They were awarded the prize for their breakthrough research on how to treat stomach ulcers, the Nobel jury said.
They "made the remarkable and unexpected discovery" that gastritis as well as peptic ulcer disease is the result of a stomach infection caused by the bacterium Helicobacter pylori, it said.
Marshall, 54, is from Kalgoorlie, western Australia and researches at the QEII Medical Centre in Nedlands. Warren, 68, was born in Adelaide in south Australia and now lives in Perth where he worked as a pathologist at the Royal Perth Hospital until 1999.
"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 jury said.
Before the discovery of the bacterium in 1982, stress and lifestyle were considered the major causes of ulcers. But it has now been firmly established that Helicobacter pylori causes more than 90% of duodenal ulcers and up to 80% of gastric ulcers.
In rich countries, infection with the bacterium is less common than in the developing world "where virtually everyone may be infected", the Nobel citation said.
Last year, the award went to two American researchers, Richard Axel and Linda B. Buck, for pioneering work on the sense of smell, explaining how we recognise thousands of odours and remember them.