Originally uploaded by laidongth

By: Wendy O.

Peptic ulcers are internal sores located in the stomach and upper intestinal tract. Ulcers cause damage to tissue which can cause internal bleeding, which can be fatal. In America, there are about 25 million people with peptic ulcers. It was originally believed that peptic ulcers were the result of stress and poor diet, but in 1982, physicians Barry Marshall and Robin Warren found a more probable culprit: bacteria. More specifically, Helicobacter pylori. This discovery has changed the way ulcers were treated from then on, and provided the foundation for finding a cure.

It was once thought that the stomach created an environment that was so acidic that bacteria would not be able to live there. So the most likely explanation for ulcers was making the environment more acidic by eating spicy food, and being under high levels of stress. We know now that spicy foods do not cause ulcers, and that stress does not increase the amount of acid in the stomach, it actually depletes it! The bacterium, Helicobacter pylori, on the other hand can cause a peptic ulcer, it can also survive in the stomachs highly acidic environment.

About half of the worlds population has the bacteria H. Pylori, but only a fraction of those people have peptic ulcers. This suggests that there are different strains of the bacteria that are more harmful, and that the persons genes, behavior, and environment may also play a role in developing an ulcer.

Most who are infected with Helicobacter pylori contract the bacteria early in life, most likely getting it from family members. The strains of the bacteria can also be differentiated from one family to another which allows geneticists to trace family ancestry, and map out migration patterns of various populations.

In 2003 geneticists led by Mark Achtman at the Max Planck Institute for Infection Biology in Berlin gathered strains of Helicobacter pylori from people located all over the world. They found that the bacteria was most abundant in people from Africa, east Asia, and Europe. Upon analyzing the bacteria further, related strains were found among groups of people living in different parts of the world which provided evidence for a common ancestry. For example, bacteria from the Maoris, a group native to New Zealand, were closely related to bacteria from people from Polynesia. This affirmed that Maoris came from Polynesia, and migrated to New Zealand several thousand years ago. In more recent migration, African strains were found in great abundance among African Americans living in Louisiana and Tennessee.

Good news about Helicobacter pylori is that it has been seen in much lower frequency in recent years, especially in wealthier nations. In the United States, less than 10% of children have the bacteria. This is most likely due to the wide availability of antibiotics, and better hygiene.

Source: Pierce, Benjamin A.. Genetics: A Conceptual Approach. 3rd. New York: W.H. Freeman & Co., 2008. Print.

Stumble it!