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Researchers
believe that the bacterium H. pylori is responsible for the majority
of ulcers of the stomach and duodenum.
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One in 10 Americans
develops an ulcer at some time in his or her life.
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H. pylori infection is common in the United States: About 20 percent
of people under 40 years old and half of those over 60 have it.
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Researchers are not certain how people contract H. pylori, but they
think it may be through food or water.
An ulcer is a sore on the lining of
the stomach or duodenum, which is the beginning of the small intestine.
Peptic ulcers are common: One cause of peptic ulcer is bacterial infection, but
some ulcers are caused by long-term use of nonsteroidal anti-inflammatory
agents (NSAIDs), like aspirin and ibuprofen. In a few cases, cancerous
tumors in the stomach or pancreas can cause ulcers. Peptic ulcers are not
caused by spicy food or stress.
Most
infected people, however, do not develop ulcers. Why H. pylori does
not cause ulcers in every infected person is not known. Most likely,
infection depends on characteristics of the infected person, the type of
H. pylori, and other factors yet to be discovered.
Researchers have found H. pylori in some infected people's saliva, so
the bacteria may also spread through mouth-to-mouth contact such as kissing.
H. pylori weakens the protective mucous coating of the stomach and
duodenum, which allows acid to get through to the sensitive lining beneath.
Both the acid and the bacteria irritate the lining and cause a sore, or
ulcer.
H. pylori is able to survive in stomach acid because it secretes
enzymes that neutralize the acid. This mechanism allows H. pylori to
make its way to the "safe" area--the protective mucous lining. Once there,
the bacterium's spiral shape helps it burrow through the lining. H.
pylori is diagnosed through blood, breath, stool, and tissue tests.
Blood tests are most common. They detect antibodies to H. pylori
bacteria. Blood is taken at the doctor's office through a finger stick.
Urea breath tests are mainly used after treatment to see whether it worked,
but they can be used in diagnosis too. In the doctor's office, the patient
drinks a urea solution that contains a special carbon atom. If H. pylori
is present, it breaks down the urea, releasing the carbon. The blood carries
the carbon to the lungs, where the patient exhales it. The breath test is 96
percent to 98 percent accurate.
Stool
tests may be used to detect H. pylori infection in the patient's
fecal matter. Studies have shown that the test, called the Helicobacter
pylori stool antigen (HpSA) test, is accurate for diagnosing H.
pylori.
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