Clinical study of common aeroallergens in Kashan with a hot and dry climate

Background: The increasing prevalence of respiratory allergies in the semi-arid climate of Kashan in central Iranian deserts, near which the first published study of hay fever was carried out 1200 years ago, is investigated for the first time using clinical data during 2006-2016. The most common aeroallergens were identified among 6650 patients who suffered from allergic rhinitis and asthma, and 623 patients who opted for skin prick test (SPT).Objectives: This study represents the first attempt in understanding the prevalence of common allergens in Kashan, based on the clinical data i.e., demographic statistics and available SPTs collected.Methods: In a retrospective cross-sectional study on 10,000 patients referred to Kashan Asthma and Allergy Clinic from 2006 to 2016, clinical information was extracted through electronic records. Considering risk factors including a family history of atopy, symptoms, smoking, and suitability of sleeping materials, sensitization to 17 aeroallergens was evaluated using SPT.Results: About 44.6% of patients had simultaneous allergic rhinitis and asthma, while 21.2% suffered concurrently from ocular allergy. The most prevalent outdoor sensitization was against weed pollens (62.3%), specially Salsola kali (69.9%), mixed extracts of Chenopodium album and Amaranthus retroflexus (58.3%) from Chenopodiaceae family, followed by grasses (44.6%), and trees (35.5%). For indoor allergens, cockroach (32.5%) was the most prevalent aeroallergen, followed by mites (27.1%), mold (23.4%), and animal dander (20.64%).Conclusion: The study showed that reaction to SPT is generally high in Kashan, especially towards weed pollens of the Chenopodiaceae family. Despite her dry climate, the living style in Kashan has traditionally been inclined to keep indoor spaces humid throughout the year and therefore more prone to such indoor aeroallergens as cockroaches, mites, and fungi infestations.