• anaphylaxis;
  • food allergy;
  • hidden allergens;
  • NSAIDs intolerance;
  • storage mites

Since the first case of oral mite anaphylaxis (OMA) was described (J Allergy Clin Immunol 1993;92:846-9), only few more cases of have been reported. The phenotype of OMA is an immediate food reaction by mite-contaminated foods (1) in patients with previous allergic rhinitis and/or asthma by sensitization to mites.

By August 2009, we compiled data of 42 patients (Table 1) with clinical history of immediate reactions to flour-based foods, suggestive of IgE-mediated hypersensitivity, and without food allergy: OMA events. All patients presented allergic rhino-conjunctivitis with/without bronchial asthma by sensitization to dust mites.

Table 1.   Clinical data of patients with oral mite anaphylaxis (OMA) events
NoSexAgeAtopy Implicated food Year event*Reaction intervalSymptoms OMANSAIDs intolerantFlour mites/g
  1. F, female; M, male; R, rhinitis; RC, rhinoconjunctivitis; A, bronchial asthma; U, urticaria; AE, angioedema; OAS, oral allergy síndrome; EIA, exercise-induced anaphylaxis; hTA, hypotension; TE, Tongue edema; N.D., Not done; AP, abdominal pain, year event*.

 1F19RCCrepes/‘012 hRC/AEA/AE/2000N.D.
 2F20RC + ACroquettes, Pancake/‘0130′U/AE/hTA/A × 2No1200
 3F25RC + APancake, Battered foods × 220–30′OAS, RC + AE × 2NoN.D.
 4F12RC + ACroquettes10–15′AEAEN.D.
 5M39RCChocolat w/cornstarch, panc’015′–20′AE- AE/UA/U/AE 2000N.D.
 6M26RC + APancake1 hUNoN.D.
 7M17RC + ACroquettes/‘0010–15′AE + U + AAE/A/2000N.D.
 8M27RCPancake × 2, Battered foods/‘025′AE × 2, AE/UAE/2003960
 9F45RPancake × 2, Battered foods5′AE/U/hTA × 3NoN.D.
10F27RC + APancake, Homemade bread5′AE × 2NoN.D.
11M37RCPancake, Croquettes15′AE/U/A × 2NoN.D.
12M17RC + APancake10′AE/U/ANoN.D.
13M16ABattered foods × 6/‘015′U × 6AE/2000N.D.
14F28RC + ACroquettes,Battered foods,cookies5U, A, hTA × 3NoN.D.
15M38RC + ACrepes, Pizza, Pancake/‘0030′hTA, U, A × 3AE/A/19891067
17F22RC + ABattered foods5′A/AENoN.D.
18M34RC + APancake/’0110′RC/A/U/AEAE/1992N.D.
19M29RC + APancake, Croquettes/‘045′AE/dysphoniaNoN.D.
20F32RC + ACroquettes/‘085′AE/AAE/1991N.D.
21F42RCPancake/’04 Muffins/‘055′AE/dysphonia/TE × 2AE/1991N.D.
22M35RC + APancake, Homemade cookies/‘005′AE/dysphagia/AAE/1982N.D.
23F23RCPancake/‘082 hAE/AAE/2002N.D.
24M35RC + AHomemade cookies/5′A/AE/U/hTANoN.D.
25F25RC + ABattered foods/‘0215′RC+AAE/A 1997N.D.
26M13RC + ACrepes, Homemade muffins/‘0815′A/U × 3AE, 2001104
29F15RC + AHallaca* with cornstarch2 hAE/ANoN.D.
30M20RC + ACookies, Battered foods, Crepes15′AE/A/UNo3905
32F20RC + ABattered food/‘0830′AE/UAE/U/20055275
33F22RC + ACrepes60′A/UNo33 634
34F15RCHomemade cookies5′A/U/AE/APNoNo mites
35M57RCBattered foods5′AE/ANoNo mites
37M33RCCrepes/‘07 AE + AAE/2007N.D.
38F13RCCrepes/‘081 hAE/U/AAE/2008N.D.
39F11RC + ACroquettes, Pancake/‘00 SAO × 2AE/1999N.D.
40M38RCBattered foods, Pancake/‘0520′AE/UAE/2000N.D.
41F26RC + ABattered foods/‘092 h + EIAAE/R/A/UAE/2001N.D.
42M23RC + ACroquettes, Battered foods/‘065′AE/U/AAE/1997N.D.

After obtaining a written informed consent from each patient for every single test, skin prick tests (SPT) were carried out with fresh and commercial extract of involved foodstuffs including flour, milk, egg, nuts, seafood, fish, fruits, meats and spices. Specific food allergy was ruled out in all patients by negative SPT, serum-specific IgE (UniCAP; Phadia, Uppsala, Sweden) and single-blinded placebo-controlled oral challenge (SBPCOC) with every single ingredient. Study of putative flours was also completed in 11 cases, detecting mites in nine samples. Interestingly, all contaminated samples showing Thyreophagus entomophagus as the unique species.

With these results, SPT were performed with a battery of aeroallergens including common mites and T. entomophagus (Leti, Madrid, Spain). SPT with T. entomophagus were positive in all 42 patients. Five T. entomophagus-sensitized patients agreed to perform SBPCOC with T. entomophagus lyophilized extract (1 mg/ml) starting with 0.1 mg and followed by increasing twofold doses of protein extract given at 60 min intervals. Total cumulative dose was 6.8 mg (47 500 mites) of lyophilized mite extract. All five patients tolerated the challenge with no side-effects.

Non-steroidal anti-inflammatory drugs (NSAIDs) hypersensitivity diagnosis was established by SBPCOC with acetylsalicylic acid (ASA). Challenge was not performed in patients who showed at least two adverse reactions with two different NSAIDs or severe reactions. Interestingly, a positive diagnosis of NSAID intolerance was established in 21 patients (50%), who suffered episodes of periorbital angioedema with/without urticaria (five with added asthma). Nineteen patients revealed episodes of NSAIDs intolerance some years before OMA.

In this report, we have demonstrated that all patients with OMA reactions had sensitization to T. entomophagus Remarkably, T. entomophagus, which has been merely described as storage mite in German farms (2) was present in stored opened flour bags in kitchens of these sensitized patients. Differently, it has not been found, as the only species implied, by other groups studying OMA, which have recognized mites triggering allergic manifestations (1, 3) after their ingestion, even after cooking.

Up to date, group 2 of mite allergens have been suggested as the most probably implicated in OMA episodes (3) as it is resistant to low pH, heating and digestion by proteases. However, Group 1, but not group 2, has been found to be masked by flour components and binding to flour’s prolamines, resulting in an underestimation of the mite content in bakery dust (4).

In our study, mite count has been low and all the SBPCOC were negative. Consequently, there might be other causes underneath. Very interestingly, a high prevalence of NSAIDs hypersensitivity has been observed in this specific population. Furthermore, it has been noticed how acetylsalicylic acid enhances anaphylactic episodes after food intake (5). However, Blanco et al. who also found T. entomophagus in some flours in the Canary Islands, were not able to demonstrate ASA in flours (1). Sato et al. (6) found a salicylaldehyde analog identified as 2-formyl-3-hydroxybenzyl formate in opisthonotal gland secretion of Dermatophagoydes pteronyssinus. It is certainly a possibility that some infested flours by mites have also salicylaldehyde analogs with a cyclooxygenase (COX) inhibitory activity. Maybe two triggers are necessary to develop an OMA episode in a susceptible patient: intake of substance with a COX inhibitory activity and the intake of the mite proteins. More extensive studies are necessary to clarify this.


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