In 1983, an Australian pathologist named Robert Warren discovered a bacterium called helicobacter pylori. He enlisted the help of his colleague Barry Marshall, who stated that this bacterium turned up consistently in the stomachs of people suffering from duodenal ulcers and stomach inflammation. He took a daring step and theorized that the bacterium actually caused the inflammation and the ulcer. He announced his findings at an international conference on gastroenterology and was promptly laughed out of the hall.
Everyone knew that diet, stress, and genetic predisposition caused ulcers not some unknown bacterium. To further discredit his theory critics pointed out that the stomach is so acidic that no bacterium can survive there. Marshall countered by proving that helicobacter pylori did cause ulcers in laboratory mice. His experiments were promptly dismissed as being inapplicable to human conditions! In a heroic gesture worthy of any second rung Hindi movie, the mad scientist swallowed some bacteria and developed gastritis.
Other researchers decided to conduct additional studies and they found that he was absolutely right. It turns out that helicobacter pylori do live in the acidic stomach. It protects itself with a coating that is acid resistant and further wraps itself in a coat of bicarbonate. This bacterium probably explains over 80 per cent of the cases of ulcers in western populations.
In the developing world nearly 100 per cent of the people are infected by this bacterium but not all suffer from ulcers. It is probably the most chronic bacterial infection in humans. The bacterium infects cells lining the stomach wall and cause gastritis. This compromises the ability of the cells to defend against the stomach acid—and you end up with an ulcer in the duodenal wall. Many details are being sorted out but the greatest triumph for the two Australians has been the near universal adoption of their theory. It has now become common to treat ulcers with antibiotics like amoxycillin. Best of all, various studies have shown that ulcers can be cured and the infection does not recur.
Now for the interesting postscript. Only 10 per cent of the people infected with the bacteria get an ulcer. It means that there is some other agent in addition to the bacterium that causes ulcers. The consensus seems to be that stress by itself does not cause ulcers.
Rather, stress worsens the impact of helicobacterpylori infection and that leads to ulcers. Repeated studies have shown that in humans, ulceration is likely to occur in people who are anxious, depressed, or undergoing severe life stressors. Some very sophisticated studies coupled with equally complicated statistical analysis have shown that in the case of massive infections with helicobacter pylori, even moderate stressors can cause ulcers. In the case of massive stressors, even a minor infection is enough to cause ulcers.