- WASHINGTON (Reuters) - A
stomach bacterium best known and reviled for causing ulcers and cancer
has been with humanity for thousands of years, U.S. researchers said on
Monday.
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- The discovery 20 years ago that Helicobacter pylori and
not spicy food or stress caused most cases of stomach cancer turned the
medical world on its head, and doctors have been avidly studying the bug
ever since.
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- A genetic study suggests the bug is nothing new, but
has been eking out a living in the stomachs of people for at least 11,000
years.
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- Helicobacter is especially common in East Asia and less
often found in Europe. Dr. Martin Blaser and colleagues at New York University
looked at Native Americans for some answers.
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- "We know that the ancestors of present-day Amerindians
migrated from East Asia to the New World more than 11,000 years ago,"
Blaser, whose findings are published in Tuesday's online issue of the Proceedings
of the National Academy of Sciences, said in a statement.
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- "We used this historical event to help us understand
how long the bacterium has been present in human populations. Our study
shows that H. pylori has been present in humans for at least 11,000 years."
-
- They studied Venezuelan Indians and Venezuelans of mixed
European descent. The team had previously found that H. pylori has specific
genetic variations. One mutation is found in East Asians only.
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- The Venezuelan Indians, descended from East Asian immigrants
who came to the Americas 11,000 or more years ago, carried bacteria with
the East Asian mutation, Blaser's team found. Mestizos of mixed descent
carried microbes with a more general genetic pattern.
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