Abstract

SANTOS, Natacha; CAROLINO, Fabrícia; AGUIAR, Ana  and  PLACIDO, José Luís. Occupational allergy to Tetranychus urticae in agricultural workers in the north of Portugal. Rev Port Imunoalergologia [online]. 2015, vol.23, n.2, pp.71-77. ISSN 0871-9721.

Background: Tetranychus urticae is a phytophagous mite, plague in several agricultural crops and responsible for symptoms of rhinitis, asthma and urticaria. However, allergy to this mite has not been previously evaluated in Portugal in an occupational setting. Aim: To evaluate the frequency of sensitization and allergy to T. urticae in different contexts of agricultural production. Methods: Skin prick tests (SPT) with airborne allergens, including domestic mites and T. urticae (Leti®), conjunctival provocation test (CPT) with T. urticae (Leti®) and a survey of occupational exposure and allergic symptoms were performed. The SPT were considered positive for a mean wheal diameter ≥ 3 mm after 15 minutes. The CPT was single-blinded with increasing concentration (0.002 - 0.02 - 0.2 - 2 mg/mL) of T. urticae extract at 10 minute intervals and considered positive in the presence of conjunctival hyperemia, palpebral edema or lacrimation. Results: We included 41 farmers, 27 (66%) male, mean age (SD) of 45 (12.3) years. Twelve worked in greenhouses, 6 in the production of green wines and 23 in Douro wines. Seven (17%) workers had a positive SPT for T. urticae (78% of atopic), 2 of which monosensitized: 3 greenhouse workers, 0 of the green wines and 4 of the Douro wines. Three workers (43% of sensitized) had positive CPT with T. urticae, all co-sensitized to mites: 2 greenhouse workers with contact urticaria with bean crop in the spring/summer and 1 Douro wine worker with occupational rhinoconjunctivitis in the spring. Of the 4 farmers sensitized T. urticae with negative CPT, 2 were asymptomatic and 2 had seasonal rhinitis. Conclusions: A high prevalence of sensitization and allergy to T. urticae was found mainly among greenhouses workers, which could be due to increased occupational exposure in this type of production.

Keywords : Agriculture; conjunctival provocation test; greenhouse; occupational allergy; spider mite; Tetranychus urticae.

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