Ulcer Bug one of "New World’s" First Immigrants

Long before Columbus "sailed the ocean blue," an ulcer bug may have traveled to the New World in the upset stomachs of ancient immigrants crossing the Bering Strait.

Samples of Heliocobacter pylori (H. pylori) taken from Native Americans are more similar to strains of the ulcer-causing bacteria from China than those from Spain or England, according to a recent study challenging theories that European conquerors first brought H. pylori to North and South America.

"The results suggest that there were multiple migrations to the Americas, and that some came from central Asia," said Dr. David Graham, a principal investigator of the study published in a recent issue of DEBS Letters. "Their bacteria left footprints."

Dr. Graham and co-investigator Dr. Yoshio Yamaoka conducted the research at the Houston VA Medical Center. Dr. Graham is a professor in the departments of medicine and molecular virology and microbiology at Baylor. Dr. Yamaoka is an assistant professor in Baylor’s department of medicine.

H. pylori is one of the most common bacterial infections worldwide and is a major cause of chronic gastritis, peptic ulcer, and cancer of the stomach. The bacteria have been infecting humans for at least 10,000 years, Dr. Graham said.

The study analyzed samples of the H. pylori bacteria taken from Eskimo and Aleut populations in Alaska, Navajos in Arizona and the Huitotos, a primitive group living in the Amazonian jungles in Columbia. Researchers found that some of the Native Columbian and Native Alaskan strains were similar, but not identical to East Asian strains, suggesting that they separated from the original Asian strain long ago.

"This is consistent with the hypothesis that H. pylori accompanied humans when they crossed the Bering Strait from Asia to the New World," Dr. Graham said. "Both the Native Columbian strains and the Native Alaskan strains were very similar."

Not all of the Native Alaskan strains were the same, which could influence current migration theories. According to the "three-wave" theory, three separate migrations of people into the New World from Asia took place, corresponding to three different Native American language groups. Other studies suggest that only a single major migration occurred or that as many as four major migration waves occurred.

One of the Native Alaskan H. pylori strains was more similar to those found in Central Asia counties such as Kazakstan.

"Studying H. pylori is another way to look at the evolution and migration of humans and their pathogens," he said. "Humans carried a lot of intestinal pathogens with them as they evolved, and H. pylori was one of the last of the significant pathogens. Only now with improved sanitation, diet, and standards of living is it disappearing."

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©2006 Texas Medical Center

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