Spider mite allergy in apple-cultivating farmers: European red mite (Panonychus ulmi) and two-spotted spider mite (Tetranychus urticae) may be important allergens in the development of work-related asthma and rhinitis symptoms

Background: Recent investigations have suggested that the citrus red mite ( Panonychus citri) is the most important allergen affecting citrus-cultivati ng farmers with asthma, allergic rhinitis, or both. Objective: We sought to evaluate type I hypersensitivity to spider mites, p articularly the European red mite (Panonychus ulmi) and the two-spotted spi der mite (Tetranychus urticae), and to determine the relationship between h ypersensitivity to spider mites and respiratory dysfunction. Methods: We performed a cross-sectional survey. Questionnaires were given, and skin prick tests for 11 inhalant allergens common in Korea and 2 specie s of spider mites (European red mite and two spotted spider mite) were perf ormed in 725 apple-cultivating farmers in Korea. Results: Results of skin prick tests in the apple farmers indicated that Eu ropean red mite (23.2%) was the most common sensitizing allergen, followed by Tyrophagus putrescentiae (21.2%), two-spotted spider mite (16.6%), Derma tophagoides farinae (16.3%), D pteronyssinus (14.4%), cockroach (13.1%), an d Hop Japanese (Humulus Japonicus) pollen (12.0%). Positive skin responses (mean wheal size greater than or equal to 3 mm) to one or more of 13 inhala nt allergens were found in 48.2% of farmers tested, whereas 40 subjects (8. 6%) had an isolated skin response to the spider mites. Among 119 farmers,vi th work-related asthmatic symptoms, the positive skin response rates to Eur opean red mite and two-spotted spider mite were 40.4% and 27.0%, respective ly. These figures a ere significantly higher than those found among farmers without work-related symptoms (19.1% and 14.1%, respectively; P < .01). Th e prevalence of work-related asthma symptoms was higher in farmers with pos itive skin responses to spider mites than in those with negative skin respo nses to spider mites and those with positive skin responses to any allergen tested (31.4% vs 15.0% vs 21.0%, respectively; P < .05). Conclusion: Spider mites, particularly European red mite and 2-spotted spid er mite, are common sensitizing allergens in apple-cultivating farmers. The se spider mites may be important causative allergens in the development of work-related respiratory symptoms in these workers.