Monthly variation of Dermatophagoides allergens and its influence on respiratory allergy in a high altitude environment (Quito, 2800 m a.s.l. in Andean Ecuador)

Abstract

Background Seasonal variation of Dermatophagoides allergens and its influence in allergic respiratory airway diseases has not been investigated in Andean cities. The objective of this study was to evaluate those parameters in a city located in the Andean mountains. Methods Der p1 and Der f1 were measured in dust samples from mattresses in 13 houses in Quito (2800 m above sea level). Samples were collected monthly from August 2004 to July 2005. Patients presenting to a local outpatient allergy clinic with asthma and rhinitis and isolated allergy to Dermatophagoides were analysed to determine if a correlation existed between seasonal Der allergen levels and the number of patients presenting with allergies. Results High levels of dust mites and humidity were observed throughout the year. The highest geometrical mean values of allergens were detected in April ( Der p1, 10.15 μg/g) and May ( Der f1, 13.03 μg/g), whilst the lowest levels were detected in August (Der p1, 4.26 μg/g), and September (Der f1, 1.4 μg/g). Of the 361 patients examined, 182 were allergic to Dermatophagoides, (45.6% asthmatics, 97.8% rhinitics, and 43.4% with both diseases). Patient presentation spiked in August, and from February to May. However, there was not a significant correlation between mite allergen concentrations and humidity or the number of patients presenting with allergies. Conclusions Dust samples from mattresses in Quito revealed high concentrations of Der p1 and Der f1. We observed a trend towards increased presentation of asthmatic and rhinitic patients in the months with highest levels of allergens.