title: The pathophysiology of the hygiene hypothesis.
abstract: There has been a considerable increase in the diagnosis of allergic diseases over the last decades. Prevalence of allergies in high-income countries and urban areas appears higher than in rural environments. While environmental factors like pollution or nutrition can be important, it is more likely that in the end they have a small association with allergies. Childhood infections and exposure to certain microbial antigens on the other hand seem to present a strong negative correlation with allergies, and therefore the increase of the allergic burden in the Western world has been frequently related to a decline of childhood infections giving birth to the "Hygiene Hypothesis". We address the issue with emphasis on the associated pathophysiology tightrope walking between the skepticism of the critics, which cast doubt on it, and the pilgrims' belief of having discovered allergy's Holy Grail.
authors.affiliation: Department of Otorhinolaryngology, University of Crete School of Medicine, Crete, Greece. eprokopakis@gmail.com
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Prokopakis
authors.forename: Alexios
authors.initials: A
authors.lastname: Vardouniotis
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Kawauchi
authors.forename: Glenis
authors.initials: G
authors.lastname: Scadding
authors.forename: Christos
authors.initials: C
authors.lastname: Georgalas
authors.forename: Peter
authors.initials: P
authors.lastname: Hellings
authors.forename: George
authors.initials: G
authors.lastname: Velegrakis
authors.forename: Livije
authors.initials: L
authors.lastname: Kalogjera
mesh_terms: D000485:Allergens / Q000009:adverse effects; D001249:Asthma / Q000209:etiology / Q000503:physiopathology*; D004781:Environmental Exposure / Q000009:adverse effects; D057890:Epigenomics; D006801:Humans; D061148:Hygiene Hypothesis; D006967:Hypersensitivity / Q000209:etiology / Q000503:physiopathology*; D065631:Rhinitis, Allergic; D012221:Rhinitis, Allergic, Perennial / Q000209:etiology / Q000503:physiopathology*
chemical_list: D000485:Allergens