As reported in the Journal of Clinical Investigation, joint research by the University of Zurich and the Johannes Gutenberg University of Mainz has indicated that infection with the gastric bacterium Helicobacter pylori provides protection against allergy-induced asthma. In their experiment, the researchers infected mice with H. pylori bacteria. The mice that were infected at the age of a few days old developed immunological tolerance to the bacterium and reacted insignificantly to asthma-causing allergens. Mice that were not infected with H. pylori until they became adults, however, had a much weaker defence. The results confirmed the hypothesis recently put forward that the dramatic increase in allergic diseases in Western societies is linked to the rapid disappearance of specific micro-organisms that populate the human body.