Characteristic features of cockroach hypersensitivity in Turkish asthmatic patients

Exposure to cockroach has been reported to cause asthma in many parts of the world. Although house-dust-mite is known to be the most important indoor allergen in Turkey, there are few data on the prevalence of allergy to cockroaches. Therefore, we evaluated the prevalence of cockroach sensitivity in asthmatic Turkish patients to see whether it is also an important source of asthma in addition to house-dust mites. A total of 206 patients demonstrating the characteristic features of asthma were included in the study. Sixty-three percent of the patients were considered atopic, and 37% were found to be nonatopic by skin prick tests. Mite allergens were the most common cause of indoor allergy (50%), while cockroach sensitivity was detected in 25.7% of all the asthmatics. Among all cockroach-sensitive patients, 70% were also positive for mites. A female predominance was observed in cockroach-sensitive patients, as 44% of atopic women and 34% of atopic men had positive skin tests with cockroach allergen. The average duration of asthma was 7.1+/-5.6 years in cockroach-sensitive asthmatics, and there was no difference between groups in average duration of asthma (P>0.05). Mild, moderate, and severe asthmatics constituted 73.6%, 20.7%, and 5.7% of the cockroach-sensitive patients, respectively. These data indicate that cockroach is also an important source of domestic infestation in Turkey. Thus, it seems reasonable to suggest the need for cockroach allergen in the routine battery of inhalant skin tests in this geographic location. However, possible cross-reactivity with mites has to be taken into consideration during the clinical evaluation of subjects with cockroach sensitivity, especially in our patient population with such high rates of house-dust-mite allergy.