News Life How a stomach bug may ward off asthma H. pylori’s influence on immune system could reduce airway disease By Tina Hesman Saey February 8, 2012 at 11:02 am - More than 2 years ago Share this:Share Share via email (Opens in new window) Email Share on Facebook (Opens in new window) Facebook Share on Reddit (Opens in new window) Reddit Share on X (Opens in new window) X Print (Opens in new window) Print A bacterium that causes ulcers and stomach cancers may protect against asthma by teaching the immune system tolerance, a new study in mice shows. Stomach cancer cases have dropped in North America and Europe as the number of people who carry the bacterium Helicobacter pylori has declined.