Tetranychus urticae allergy in a population without occupational exposure

Eur Ann Allergy Clin Immunol. 2014 Jul;46(4):137-41.


Background: Tetranychus urticae is a phytophagus mite found in the leaves of numerous plants. High sensitization rates have been demonstrated, however, provocation tests have only been performed in an occupational setting.

Objective: To assess accuracy of skin prick tests and clinical relevance of T. urticae sensitization by means of conjunctival provocation tests (CPT) in a population without occupational exposure and to evaluate possible environmental risk factors for T. urticae allergy.

Methods: Patients ≥ 18 years old sensitized to T. urticae (n = 12) and a non-sensitized control group (n = 12) were invited to perform CPT with T. urticae and fulfill a questionnaire including demographic data, questions on environmental exposure to T. urticae and allergy symptoms/diagnosis. A single-blinded placebo-controlled CPT with T. urticae (Leti®) was performed with increasing concentrations (0.002, 0.02, 0.2 and 2 mg/mL) and considered positive if conjunctival hyperemia, palpebral edema or lacrimation were observed in the tested eye.

Results: Of T. urticae sensitized patients (mean wheal 4.4 ± 1.5 mm), 9 had a positive CPT, including 3 monosensitized. A good diagnostic accuracy was found for skin prick tests: AUC = 0.952, sensitivity = 100%, specificity = 80%, positive likelihood ratio = 5 and negative likelihood ratio = 0 for a 3 mm wheal. No differences were found between allergic and non-allergic subjects regarding atopy, allergic disease or farming activities.

Conclusions: A high prevalence of allergy to Tetranychus urticae was found in the north of Portugal. Future studies with a larger number of patients are needed to evaluate its relation to clinical symptoms and the impact of environmental factors.

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

Publication types

  • Clinical Trial

MeSH terms

  • Adult
  • Animals
  • Area Under Curve
  • Conjunctiva / immunology
  • Female
  • Humans
  • Hypersensitivity / diagnosis*
  • Hypersensitivity / epidemiology*
  • Immunologic Tests / methods*
  • Male
  • Middle Aged
  • Occupational Exposure
  • Portugal / epidemiology
  • Prevalence
  • Sensitivity and Specificity
  • Skin Tests
  • Tetranychidae / immunology*