Objective: House dust mites were found to be the most prevalent inhalant allergens in our region. We aimed to investigate the sensitization rate to Blomia tropicalis and to evaluate the cross-reactivity between Dermatophagoides pteronyssinus and B. tropicalis in children with persistent allergic symptoms.

Materials and Methods: In order to determine the sensitization rate to these two mites, skin prick tests and specific IgE levels were used. Additionally, we performed nasal and bronchial challenges in a group of 38 patients who sensitized to both D. pteronyssinus and B. tropicalis.

Results: Skin prick tests and specific IgE levels with D. pteronyssinus and B. tropicalis were performed in 165 children with asthma and/or rhinitis having persistent allergic symptoms. Then, a total of 46 nasal and 30 bronchial challenges were conducted with both mite species. The sensitization rate to B. tropicalis was found 37.4% using prick tests and 42.4% using CAP results. Nasal challenges were performed in 23 patients and all had positive results with D. pteronyssinus. 20 out of 23 (86.9%) patients had positive nasal challenges with B. tropicalis. Bronchial challenges were conducted in 15 patients and all of them had positive challenge with D. pteronyssinus except one. Twelve (80%) out of 15 patients had positive bronchial challenges with B. tropicalis.

Conclusion: We found that the sensitization rate to B. tropicalis is not as high as D. pteronyssinus in our patients with persistent allergic symptoms.