POSITIVE NASAL CHALLENGE RESPONSES TO BLOMIA-TROPICALIS

Background: Blomia tropicalis, a dust mite commonly found in subtropic al and tropical environments, is the fourth most common mite in the Un ited States. Thirty-eight percent of 167 consecutive subjects evaluate d for allergic respiratory symptoms in the Tampa Bay area had positive skin test responses to B. tropicalis. Methods: Nasal challenges were performed in 19 subjects with allergic rhinitis; 12 had positive skin test responses to B. tropicalis (group I), and seven had negative skin test responses to B. tropicalis but positive skin test responses to D ermatophagoides pteronyssinus and D. farinae (group II). Subjects were challenged with a normal saline control solution and increasing conce ntrations of a 1 mg/ml in-house extract of B. tropicalis (1:125,000 vo l/ vol, 1:25,000 vol/vol, 1:5000 vol/vol, 1:1000 vol/vol, and 1:200 vo l/vol). Inspiratory nasal airway resistance (was measured every 5 minu tes for 15 minutes by posterior rhinomanometry at 50 Pa after each nas al challenge. Results: Nasal challenge response was considered positiv e and stopped when the mean inspiratory nasal airway resistance was gr eater than twice the mean inspiratory nasal airway resistance after th e normal saline challenge. Ten of 12 (83%) subjects in group I and non e of seven (0%) subjects in group II had positive nasal challenge resp onses to B. tropicalis (p = 0.0024). Conclusion: B. tropicalis is alle rgenic and should be considered as a cause of allergic rhinitis when e valuating a patient who lives in an area where it is endemic.