Oral mite anaphylaxis by Thyreophagus entomophagus in a child: a case report

Thyreophagus entomophagus is a storage mite, usually sited in farms [1], but not in house dust of households [2]. Sensitization to mite species might produce occupational respiratory disorders in farmers [1,3]. However, it is unusual to live in urban houses or to produce symptoms by ingestion and there is no any report of child affected.We encountered a 13-year-old boy suffering wheals, itching and diffuse erythema, cough and wheeze immediately after ingest a home-made crêpe, prepared at home with wheat flour, which was stored in kitchen for weeks. He was treated at the Emergency Department with intravenous fluids, diphenhydramine, epinephrine, and methylprednisolone, with complete symptom resolution in 2 hours. He had a previous history of mild persistent allergic rhinoconjunctivitis and sensitization to house dust mite and facial angioedema, urticaria and bronchospasm after Ibuprofen, but not any history about food allergy. Skin prick tests (SPT) to common inhalant allergens were positive to Dermatophagoides pteronyssinus, Dermatophagoides farinae or Blomia tropicalis and negative to the remainder inhalants and foodstuffs including wheat flour. Acoustic Rhinometry showed reversible mild obstruction. Forced spirometry showed a mild obstructive pattern with values -FVC: 3.98 (97%), FEV1 2.78 (79%), MEF 50% 2.22 (49%), FEF 25-75%: 1.93 (45%)-. Bronchodilator test showed a positive response with an improvement of FEV1 post 3.17 (+13%). After written informed consent signed by patient and his mother, open oral challenge (OOC) with different foodstuffs were performed. OOC with wheat and a commercial crêpe were good tolerated. Since patient's mother brought us the culprit flour, microscopic examination was performed and revealed mite contamination by Thyreophagus entomophagus (104 mites/gram). New SPT were done showing positive reactions with Cheyletus spp. and a protein extract of Thyreophagus entomophagus (Leti, Madrid, Spain). SPT to other storage mites were negative.