Allergic fungal rhinitis and rhinosinusitis.

The intent of this article is to review the published literature addressing the role of fungi as causative agents in allergic rhinitis and rhinosinusitis. Ambient mold spores are widely distributed in nature, and an estimated 3 to 10% of the world's population is allergic to molds. There are compelling epidemiologic links between mold (fungal) allergy and illnesses such as asthma and "asthma with allergic rhinitis." Fungal allergy is more prevalent in areas of high ambient mold spore concentrations. However, epidemiologic studies have failed to demonstrate a direct relationship between fungal allergy and allergic rhinitis either via outdoor or indoor exposure. Fungal allergy is clearly linked to a subset of chronic rhinosinusitis (CRS) known as allergic fungal rhinosinusitis (AFRS). This condition represents an intense allergic response against colonizing fungi giving rise to formation of allergic (eosinophilic) mucin, mucostasis, and sinus opacification. A broader role for colonizing fungi has been postulated in CRS owing to the demonstration of fungi in mucus in the vast majority of cases of CRS, and in vitro studies demonstrating that certain fungi, particularly Alternaria, elicit a "modified" allergic response in patients with CRS that is independent of IgE.