Over the last 20 years, research on a tiny, S-shaped stomach bacterium has overturned doctors' notions about the origins and history of diseases from ulcers to cancer of the stomach.
Now, some scientists who study the bacterium, Helicobacter pylori, say the tiny bug may help trace the migration of human populations across the globe.
Next week, enthusiasts from around the globe will gather in Australia to celebrate the discovery of H. pylori. While the discovery of a stomach bacterium may seem an odd thing to celebrate, this one did something big.
Two Australian scientists discovered H. pylori. Pathologist Robin Warren had noticed tiny bacteria in stomach ulcer specimens and his group managed to grow them where others had failed, in part because the members left the cultures incubating for an extra long time during their Easter vacation.
When it later proved impossible to infect animals with the microbes, colleague Barry Marshall swallowed some of the bacteria to find out if they really induced stomach inflammation.
A biopsy from his stomach showed they did.
"In retrospect, it was a little bit risky," recalls Marshall, now a scientist at the University of Western Australia's department of microbiology. "But at the time it was the only way I could see to advance knowledge of the new bug."
In the years that followed, doctors tossed out theories about stress and salty food as the primary causes of ulcers. (At one time, even "obsessional and dominant" mothers were blamed for the ulcers of their children.)
In came a new model of infectious disease--and new therapeutic approaches with antibiotics to treat ulcers and prevent stomach cancer, the world's second-leading cancer killer.
Researchers now know far more about the bacterium. They know that once inside the stomach, the bacterium uses a set of whip-like tails--called flagella--to swim briskly toward the layer of mucus that protects the lining of the stomach.
Inside the mucus, H. pylori sticks to the cells lining the stomach and uses an enzyme to neutralize the stomach's fierce acidity. While there, the microbe produces proteins that cause changes in stomach cells. Those changes, in turn, lead to inflammations that over time can produce ulcers or cancer.
Researchers also have determined the precise structure of the microbe's genome several times over. They're beginning to understand how its genes function to help it survive in the stomach and trigger disease.
