Chitinases produced in the human body (known as "human chitinases") may be related in response to allergies, and asthma has been linked to enhanced chitinase expression levels [REF].
Human chitinases may explain the link between some of the most common allergies (dust mites, mold spores-both of which contain chitin) and worm (helminth) infections, as part of one version of the hygiene hypothesis[REF][REF][REF] (worms have chitinous mouthparts to hold the intestinal wall).