Citrus red mite (Panonychus citri) is the most common sensitizing allergenof asthma and rhinitis in citrus farmers

Objective To evaluate type I hypersensitivity to citrus red mite (Panonychu s citri), its prevalence, and relationship to respiratory dysfunction, a cr oss-sectional survey was performed among citrus farmers on Cheju Island, Ko rea. Materials and methods Questionnaires, and skin prick test responses to 11 c ommon inhalant allergens and citrus red mite were performed in 181 citrus f armers, and serum-specific IgE antibodies to citrus red mite were measured by ELISA in sera of 123 subjects. To determine airway hyperresponsiveness, methacholine bronchial provocation tests were performed in 55 subjects who complained of recurrent lower respiratory symptoms. Results The prevalence of asthma-based on presence of asthmatic symptoms on the questionnaire and airway hyperresponsiveness to methacholine, and alle rgic rhinitis based on presence of nasal symptoms on the questionnaire and positive skin-test response were 12.1% and 19.3%, respectively. The positiv e rate of skin responses to one or more of 11 common inhalant allergens exc luding citrus red mite was 17.1%, and if citrus red mite was included, 25.9 % of farmers had positive responses. On skin prick tests, citrus red mite ( 16.5%) was the most common sensitizing allergen, followed by cockroach (11. 0%), Dermatophagoides pteronyssinus (9.9%), and D. farinae (9.3%). Among fa rmers with asthma and allergic rhinitis, the positive skin responses to cit rus red mite were noted in 54.5 and 68.5%, respectively. Serum-specific IgE antibodies to citrus red mite were detected in 45 farmers (36.5%) of the 1 23 tested, and there was significant correlation between specific IgE level and weal (A/H ratio) to citrus red mite (r = 0.57, P < 0.001). The prevale nce of asthma was higher in subjects with positive skin responses or high s erum-specific IgE antibodies to citrus red mite than in those without skin response or serum specific IgE (P < 0.05, respectively). Conclusion Citrus red mite is the most important allergen in citrus farmers with asthma and rhinitis in which causative allergen has not been identifi ed. It should be included in the skin test battery for screening the causat ive allergen in farmers exposed to citrus red mite.