Sensitization and exposure to house dust and storage mites in high-altitude areas of ecuador.

BACKGROUND: Few studies have addressed exposure and sensitization to mite allergens in Andean countries. OBJECTIVES: To identify the main mite species in 3 locations at different altitudes in Ecuador and to verify skin test reactivity to various mite species in allergic individuals in Quito, Ecuador. METHODS: Mattress dust samples were collected in Quito (2,800 m above sea level), Cuenca (2,500 m above sea level), and Guayaquil (sea level). Mite species present in the samples were isolated, identified, and counted. Der p 1 and Der f 1 levels were measured using monoclonal antibody-based enzyme immunoassays. Four hundred thirty-five patients in Quito diagnosed as having allergic rhinitis or asthma underwent skin testing with commercial extracts of Dermatophagoides pteronyssinus, Dermatophagoides farinae, Blomia tropicalis, Tyrophagus putrescentiae, and Lepidoglyphus destructor. In addition, Glycyphagus domesticus, Acarus siro, and Aleuroglyphus ovatus were tested in 362, 262, and 279 patients, respectively. RESULTS: Twenty-one mite species were identified. Large populations of mites were detected above 2,500 m of altitude. All the dust samples contained detectable levels of Der p 1 or Der f 1. Positive skin prick test reactions to D. pteronyssinus, D. farinae, B. tropicalis, L. destructor, T. putrescentiae, A. ovatus, A. siro, and G. domesticus were obtained in 60.9%, 56.8%, 17.0%, 19.3%, 10.6%, 15.8%, 8.8%, and 11.0% of the patients, respectively. CONCLUSIONS: Most analyzed mattresses contained several species of mites. Mite allergen levels were high. This study confirms the importance of house dust and storage mite allergens in Ecuador in areas above 2,500 m of altitude, where humidity remains high year round.

Mite allergen exposure, sensitisation and clinical symptoms in Valdivia, Chile.

One hundred consecutive asthmatic paediatric patients were evaluated and skin tested with a battery of skin prick test reagents, including 8 different standardized house dust mite extracts. Asthma severity was graded according to the Global Initiative for Asthma (GINA) document in mild persistent (52 patients), moderate persistent (39) and severe persistent (9). Sixty patients had asthma and allergic rhinitis, 12 asthma and eczema, and 8 asthma, allergic rhinitis and eczema. The patient population was divided into 2 different socioeconomic groups (50 patients per group) based on a standardized, validated questionnaire. A dust sample was collected with an adapted vacuum cleaner from the mattress of each patient and analysed for Der p 1, Der f 1 and Der p 2 allergen content using monoclonal antibodies. Eighty patients were skin test positive to at least one mite species. All positive skin test patients were positive to Dermatophagoides pteronyssinus, 99% to D. farinae, 92% to Euroglyphus maynei, 80% to Lepidoglyphus destructor, 73% to Tyrophagus putrescientae, 72% to Blomia tropicalis; 70% to Acarus siro and 68% to Chortoglyphus arcuatus. All patients with severe persistent asthma had a positive skin test to mites, 85% in the moderate group, and 73% in the mild group (p < 0.01). 95% of patients with asthma and allergic rhinitis had a positive skin test to mites, 92% of patients with asthma and eczema and 100% of patients with asthma, allergic rhinitis and eczema; (p < 0.01). Mean Der p 1, Der f 1 and Der p 2 allergen concentrations were 18.3, 0.6 and 5.6 microg/g of mattress dust, respectively. Mean Der p 1 allergen levels in the middle-low socioeconomic group were significantly higher than in the middle high group (p < 0.01). There is a high rate of allergic sensitisation among pediatric asthmatic patients in Chile. More than one species are implicated, although sensitisation and exposure to D. pteronyssinus predominates. Mite allergic patients are exposed to high mite allergen concentrations, exceeding previously established risk levels for sensitisation and symptoms.

Association between mite allergen (Der p 1, Der f 1, Blo t 5) levels and microscopic identification of mites or skin prick test results in asthmatic subjects.

BACKGROUND: Mite allergens have been involved in airway sensitization and allergic diseases. Immunoassays for the identification and quantifiction of house dust mite (HDM) allergens are useful to improve the knowledge of regional mite fauna and the remediation of mite allergens in allergic diseases. The present study analyzed the association between levels of HDM allergen and results of mite identification or skin prick test (SPT) in two different areas of Bahia, Brazil. METHODS: Forty-two asthmatic subjects from a rural area (group I; n = 21) and a slum (group II; n = 21) were evaluated through SPT with HDM allergens and had dust samples collected at their homes for mite identification and allergen measurements. RESULTS: Positive SPT to Dermatophagoides pteronyssinus, Dermatophagoides farinae and Blomia tropicalis allergens were observed in 42.9, 38.0 and 42.9% subjects from group I and in 47.6, 19.0 and 33.3% subjects from group II, respectively. D. pteronyssinus and B. tropicalis were identified in approximately 76 and 50% of samples from both groups, respectively. D. farinae was identified in 38.0 and 9.5% of samples from groups I and II, respectively (p < 0.005). Der p 1, Der f 1 and Blo t 5 detection were associated with mite identification (p < 0.05). Association between HDM allergen levels over 2 microg/g of dust and positive SPT occurred only with D. pteronyssinus (p < 0.0001). CONCLUSIONS: D. pteronyssinus was the most prevalent mite species in this study followed by B. tropicalis and D. farinae. Immunoassays done to measure mite allergens were associated with mite-species identification. We conclude that these three mite species must be included on panels for the diagnosis of allergic airway diseases in subjects living in such regions.