House dust mites: new food allergens

In atopic individuals with respiratory sensitization to house dust mites, ingestion of food contaminated with Dermatophagoides farinae, Dermatophagoides pteronyssinus, and/or storage mites can cause acute anaphylaxis. Erben et al. reported the first case in 1993. We found 55 reported cases. The 33 women and 22 men (sex ratio, 1:5) were 5 to 45 years of age (mean, 22 to 23 years); half the patients were 18 or younger. Time to symptom onset after food ingestion was only 5 minutes to 2 h. The patients had rhinoconjunctivitis, asthma or atopic dermatitis and had been previously sensitized to airborne mites. Manifestations of anaphylaxis were as follows, in order of decreasing frequency: asthma, angioedema, rhinitis, urticaria, gastrointestinal disorders, and anaphylactic shock, which was life-threatening in two of ten cases. In some patients, the diagnosis was missed at the first episode. The many incriminated foods include pancakes, cakes, breaded foods, pizzas, polenta, and various Japanese dishes such as okonomi-yaki. The mites proliferate during storage under improper conditions. Growth of mites is particularly fast at temperatures higher than 25degrees C and relative humidity higher than 70%, which explains that most reported cases occurred in hot climates. However, cases that occur during the hot season in temperate climates are probably underdiagnosed. In patients with food anaphylaxis and negative tests for food allergens, contamination by mites should be considered. In reported cases, D. farinae was the most commonly implicated mite, followed by D. pteronyssinus, Acarus siro, Tyrophagus putrescentiae, Thyreophagus entomophagus, Suidisia nesbitti, Aleuroglyplus and Ascidae spp. Examination under the microscope can show a large amount of mites: in one estimation the range was 4,900 to 52,200 mites per gram of flour! The 60% rate of sensitivity to aspirin or nonsteroidal anti-inflammatory drugs among these patients is generating considerable interest but remains unexplained. This new risk of food-related disease requires that patients with sensitivity to mites take a number of basic precautions: they should be aware of the potential risk associated with foods such as pancakes, cakes, and pizzas; store flours in airtight containers; keep these containers in the refrigerator to prevent mite growth; and inform the catering industry of this new risk. 0 2002 Editions scientifiques et medicales Elsevier SAS.