The bug Helicobacter pylori, is a bacterium that has co-existed with humans for at least 50,000 years, and may lead to peptic ulcers and stomach cancer.
However, researchers studying 7,412 kids found that those between the ages of 3 and 13 who carry the bug are nearly 59 percent less likely to have asthma.
"Our findings suggest that absence of H. pylori may be one explanation for the increased risk of childhood asthma," says Yu Chen, Ph.D., assistant professor of epidemiology at New York University School of Medicine and a co-author of the study.
"Among teens and children ages 3 to 19 years, carriers of H. pylori were 25 percent less likely to have asthma."
They also noted that H. pylori carriers in teens and children were also 40 percent less likely to have hay fever and associated allergies such as eczema or rash.
Dr. Chen collaborated on the survey with Martin J. Blaser, M.D., the Frederick H. King Professor of Internal Medicine, chair of the department of medicine, and professor of microbiology at NYU Langone Medical Center.
"Our hypothesis is that if you have Helicobacter you have a greater population of regulatory T-cells that are setting a higher threshold for sensitization," Dr. Blaser said.
The study appears in the July 15, 2008, online issue of The Journal of Infectious Diseases.