401 House Dust Mite Fauna and Its Relationship to Allergen Skin Tests in Six Mexican States

BACKGROUND: House Dust Mites (HDM) are important respiratory allergens all over the world. In Mexico, there have been only few studies describing the HDM fauna, and mostly limited only to Mexico City. This study aimed to asses the HDM fauna and its relationship to allergen sensitization in different cities with climatic variations in Mexico. METHODS: A total of 60 dust samples were collected from mattresses in 6 Mexican states: Oaxaca, Tamaulipas, Veracruz, Puebla, Chiapas and Campeche; during a period from February to August 2010 and in May 2011. Mites were isolated under a stereomicroscope using lactic acid - 0.9% NaCl solution (1:1). Identification was performed on fixed slides prepared with Hoyer solution. Skin Tests were performed with allergen extracts of different HDM species in the 60 mattress' owners, which had previously been diagnosed with respiratory allergy. RESULTS: The Pyroglyphidae family was predominant, being found in 100% of dust samples. Dermatophagoides pteronyssinus (Dp) and Dermatophagoides farinae (Df) were the species most frequently found (in over 90% of samples). These findings were in agreement with the Skin Tests results, where 100% of patients were positive to Dp whereas 70% was positive to Df. It was evidenced for the first time the presence of Blomia tropicalis (in Tamaulipas, Veracruz and Campeche) and Dermatophagoides siboney (in Campeche). Both species are important allergenic sources in tropical/subtropical climates, and the last one had been previously reported only in Cuba. Other species found were Acarus siro, Cheyletus sp., Suidasia pontificia, and Gamasidae and Oribatidae families. CONCLUSIONS: These results confirm the importance of pyroglyphid HDM, as indoor sensitizers in different climatic and geographical regions in Mexico, as well as, the relevance of tropical species, particularly Blomia tropicalis, in certain areas. They support the need of using allergen extracts of these mite species for improving allergen-specific diagnosis and immunotherapy.