402 Oral Mite Anaphylaxis is Caused by Mite-contaminated Okonomiyaki Mix in Japan

BACKGROUND: Anaphylaxis after the ingestion of foods contaminated with mites has recently been reported. It is an immediate and potentially life-threatening reaction in patients with previous allergic rhinitis and/or asthma following the ingestion of mite-contaminated foods. Case series and case reports thus far have shown that mite-contaminated wheat flour is the major cause of oral mite anaphylaxis. However, we have encountered 8 cases of oral mite anaphylaxis in our hospital not caused by mite-contaminated wheat flour but by mite-contaminated okonomiyaki mix. METHODS: To review the current literature, in addition to our patients, we performed a MEDLINE search of articles on oral mite anaphylaxis in Japan up to June 2011 and collected patient characteristics, interview contents, results on specific IgE against mites, wheat, and pollen and other antigens, results of skin prick tests including those using extracts from mites and/or culprit flours, and microscopic examination results. RESULTS: We found thirty oral mite anaphylaxis patients in Japan twenty-eight (93.3%) of whom ingested okonomiyaki or takoyaki, prepared at home using okonomiyaki mix (24 patients) or takoyaki mix (4 patients), respectively, which was previously opened and stored for months at ambient temperature. Takoyaki mix is similar to okonomiyaki mix, which is composed of flour, dried scallop, bonito, and mackerel. The other 2 patients ingested pancake mix. Microscopic examination of thirteen patients’ mixes revealed contaminating mites. Thyreophagus putrescentiae, Dermatophagoides pteronyssinus, Dermatophagoides farinae were found in mix samples of 4, 3, and 3 patients, respectively. The specific IgE against each mite is generally upregulated, which might be affected by cross-reactivities to other mites. Especially, the specific IgEs to Dermatophagoides pteronyssinus and Dermatophagoides farina were more than class 2 in all cases. It is suggested that mites are attracted to the flavors of okonomiyaki and takoyaki mixes and invade from a crack in a flour sack, and proliferate under favorable conditions. CONCLUSIONS: Mite-contaminated flavored mix is a major cause of oral mite anaphylaxis in Japan.