" The study, based on an analysis of a health survey of 7,663 adults, showed that a virulent strain of H. pylori was especially associated with being asthma-free before the age of 15. People who carry the strain were 40 percent less likely to have had asthma at an early age than those who didn't carry the strain. The study also found that the microbe was associated with protection against ragweed and other allergies due to pollens and molds particularly among younger adults. "

" "Ultimately, the potentially protective properties of Helicobacter are consistent with one another," explains Martin J. Blaser, M.D., the Frederick H. King Professor of Internal Medicine, Chairman of the Department of Medicine, and Professor of Microbiology at NYU School of Medicine, who has been studying H. pylori for more than 20 years. "

" "These properties point toward a much more complex view of the organism - not just as ulcer-pathogen or cancer-pathogen, but as an organism that has its costs and benefits to us," says Dr. Blaser. "The relative costs and benefits clearly differ among individuals." "

" Dr. Blaser performed the study with Yu Chen, Ph.D., MPH, assistant professor in the Department of Environmental Medicine at NYU School of Medicine, a new faculty member with expertise in epidemiology. "

" H. pylori lives in the mucous layer lining the stomach where it persists for decades. It is acquired usually before the age of 10, and is transmitted mainly in families. Dr. Blaser's previous studies have confirmed the bacterium's link to stomach cancer and elucidated genes associated with its virulence, particularly a gene called cagA. "

" Over recent years, Dr. Blaser began to suspect that the organism, the dominant bacteria in the stomach, may play a role in human health as well as disease. This observation, he says, is consistent with a theory called the hygiene hypothesis. It suggests that exposure to microbial infections in early childhood prevents or diminishes the development of allergies and asthma. "

" Dr. Blaser has proposed that H. pylori may protect against diseases of the upper gastrointestinal tract, such as gastroesophageal reflux disease (GERD), which may lead to Barrett esophagus, a premalignant condition, and adenocarcinoma of the esophagus. All of these conditions have become more common in developed countries - esophageal cancer of this type is the fastest rising cancer in the United States - as H. pylori has become far less common due to improved sanitation and widespread use of antibiotics, says Dr. Blaser. (At the same time, the incidence of peptic ulcers and gastric cancer has declined in developed countries.) "

" Today, less than 10 percent of children carry the organism in industrialized countries, while some 90 percent of children are infected usually by age 5 in developing countries. "This bacterium has been the dominant organism in our stomach for tens of thousands of years, and it can't disappear from us without consequences," says Dr. Blaser. He says that a substantial body of work now shows that H. pylori helps protect against GERD and the conditions it leads to in the esophagus. "

" "The hypothesis that colonization of H. pylori, especially cagA strain, is protective of asthma risk needs to be tested by prospective studies. The findings from our study and others will collectively provide evidence," says Dr. Chen. "

" If the relationship between H. pylori and asthma is confirmed in other studies, which is always the yardstick of scientific validity, then it raises the question about whether "we should be trying to eliminate Helicobacter from children," says Dr. Blaser. "This is probably the first time in human history that we have children who are growing up without Helicobacter guiding their immune responses," he says. "By the repeated courses of antibiotics
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