Helicobacter Pylori bacterium, which usually causes ulcers and stomach cancer may protect children from developing asthma, a study published online in the Journal of Infectious Diseases suggests.

Lead authors Yu Chen, assistant professor of epidemiology at New York University School of Medicine and Martin J. Blaser, MD professor of microbiology at NYU Langone Medical Center along with their colleagues analyzed data on 7,412 US children from the National Health and Nutrition Survey conducted from 1999 to 2000 by the National Center for Health Statistics.

The study found that children ages 3 to 13 who tested positive for H. pylori were 59 percent less likely to have asthma compared to children who did not have the bacterium.

The study showed that 5.4 percent of children born in the 1990s tested positive for H. pylori. Also, the presence of the bacterium was linked to less wheezing and dermatitis, eczema or rash.

“The disappearance of Helicobacter ... is consistent with the decline of both ulcer disease and stomach cancer. It is also consistent with the rise of asthma and esophageal diseases like GERD (gastric reflux disease) and adenocarcinoma (cancer) of the esophagus,” Blaser said.

The researchers support the “hygiene hypothesis” according to which humans are more prone to allergic disorders because of a lifestyle that may be too “clean.” When the bacterium is present, the stomach is lined with immune cells called regulatory T cells. These cells help regulate body’s response to invaders. Without the cells, a child may be more sensitive to allergens, therefore to asthma.

Also, previous studies have shown that antibiotics used to treat H. pylori early in childhood increases risk of asthma and there is a great body of evidence that parents and doctors are using antibiotics like water. This practice needs to be stopped because children’s immune system will no longer know how to fight allergens.

Asthma is a chronic disease that causes the airways in the lungs to swell and become inflamed. Although there is no cure, medication can help control the disease and relieve pressure in the airways during an attack.

According to the Centers for Disease Control and Prevention, about 20 million Americans have asthma, including 9 million children. The number of affected children has more than doubled since the 1980s, the same figures show.