Systemic anaphylaxis after the ingestion of pancake contaminated with the storage mite Blomia freemani

Oral mite anaphylaxis: who, when, and how?

PURPOSE OF REVIEW

To present an update on the recent advances in the understanding of the mechanisms and practical management of oral mite anaphylaxis (OMA, pancake syndrome).

RECENT FINDINGS

Among novel observations regarding OMA, this review highlights the increased prevalence of aspirin/NSAID hypersensitivity inpatients affected by OMA, the association of OMA with exercise-induced anaphylaxis, the presentation of OMA simulating acute asthma, the occurrence of OMA in childhood, the high severity and lethal potential of OMA, the contamination of other foods, such as oat and corn flour with mites, and the simultaneous induction of OMA symptoms in more than one individual exposed to the same food source.

SUMMARY

OMA is a severe, potentially lethal, acute allergic condition that should be suspected whenever symptoms begin soon after the intake of mite-contaminated foods. Physician awareness on this clinical picture is of paramount importance to establish a correct diagnosis and to implement adequate preventive measures to help patients at risk to avoid its occurrence.

The Role of Dust Mites in Allergy

House dust mites are an unsurpassed cause of atopic sensitization and allergic illness throughout the world. The major allergenic dust mites Dermatophagoides pteronyssinus, Dermatophagoides farinae, Euroglyphus maynei, and Blomia tropicalis are eight-legged members of the Arachnid class. Their approximately 3-month lifespan comprises egg, larval, protonymph, tritonymph, and adult stages, with adults, about one fourth to one third of a millimeter in size, being at the threshold of visibility. The geographic and seasonal distributions of dust mites are determined by their need for adequate humidity, while their distribution within substrates is further determined by their avoidance of light. By contacting the epithelium of the eyes, nose, lower airways, skin, and gut, the allergen-containing particles of dust mites can induce sensitization and atopic symptoms in those organs. Various mite allergens, contained primarily in mite fecal particles but also in shed mite exoskeletons and decaying mite body fragments, have properties that include proteolytic activity, homology with the lipopolysaccharide-binding component of Toll-like receptor 4, homology with other invertebrate tropomyosins, and chitin-cleaving and chitin-binding activity. Mite proteases have direct epithelial effects including the breaching of tight junctions and the stimulation of protease-activated receptors, the latter inducing pruritus, epithelial dysfunction, and cytokine release. Other components, including chitin, unmethylated mite and bacterial DNA, and endotoxin, activate pattern recognition receptors of the innate immune system and act as adjuvants promoting sensitization to mite and other allergens. Clinical conditions resulting from mite sensitization and exposure include rhinitis, sinusitis, conjunctivitis, asthma, and atopic dermatitis. Systemic allergy symptoms can also occur from the ingestion of cross-reacting invertebrates, such as shrimp or snail, or from the accidental ingestion of mite-contaminated foods. Beyond their direct importance as a major allergen source, an understanding of dust mites leads to insights into the nature of atopy and of allergic sensitization in general.

Regional Differences in Food Allergies

The prevalence of food allergies is increasing worldwide. To understand the regional specificities of food allergies and develop effective therapeutic interventions, extensive regional epidemiological studies are necessary. While data regarding incidence, prevalence, regional variation, and treatment in food allergies are available for western countries, such studies may not be available in many Asian countries. China accounts for almost 20% of the world's population and has a vast ethnic diversity, but large-scale meta-analyses of epidemiological studies of food allergy in China are lacking. A literature search revealed 22 publications on the prevalence of food allergy in Chinese populations. A review of these studies showed that the prevalence of food allergies in China is comparable to that in western countries, even though the Chinese diet is vastly different from that of the West and may vary even greatly within China, and finally, specific antigenic triggers of food allergy vary between China and the West and also within China. Current clinical management of food allergy in China includes allergen-specific immunotherapy, Chinese herbal medicine, acupuncture, and Western medicine. This study demonstrates an unmet need in China for a thorough investigation of the prevalence of food allergies in China, the specific foods involved, and characterization of the specific antigenic triggers of food allergy with respect to ethnicity, age, and diet in China.

Challenges of managing food allergy in the developing world

Food allergy (FA) is currently a significant health care problem in the developing world. Widely varying study populations and methodologies, the use of surrogate markers such as self report or hospitalization rates due to anaphylaxis rather than objective methods, limits robust estimation of FA prevalence in low income settings. Also, allergy is under-recognized as a clinical specialty in the developing world which compromises the chance for accurate diagnosis. In this review, most published data on food allergens from developing or low income countries are displayed. The diagnostic challenges and limitations of treatment options are discussed. It seems that FA is an under-appreciated health care issue in the developing world, and accurate determination of its burden in low-income settings represents an important unmet need. Multicenter surveillance studies, using standardized methodologies, are, therefore, needed to reveal the true extent of the problem and provide epidemiological clues for prevention. Preventive strategies should be tailored to fit local circumstances in different geographic regions. In addition, studying the gene environment interactions and impact of early life microbiota on the expression of FA in developing communities would be worthwhile. Efforts and resources should be directed toward public health education and training of health care providers dealing with food allergic patients.

Allergens of Blomia tropicalis: An Overview of Recombinant Molecules

Allergic diseases are considered a major problem for healthcare systems in both developed and developing countries. House dust mites are well-known triggers of allergic manifestations. While the Dermatophagoides genus is widely distributed globally, Blomia tropicalis is the most prominent mite species in the tropical and subtropical regions of the world. Over the last decades, an increase in sensitization rates to B. tropicalis has been reported, leading to increased research efforts on Blomia allergens. In fact, 8 new allergens have been identified and characterized to different degrees. Here, we provide an overview of recent developments concerning the identification and production of recombinant Blomia allergens, as well as their structural and immunological characterization. Although considerable progress has been achieved, detailed molecule-based studies are still needed to better define the clinical relevance of Blomia allergens. Thus, the establishment of a well-standardized and fully characterized panel of allergens remains a challenge for the development of better diagnosis and therapy of allergic diseases induced by B. tropicalis.

Quantitation of Blomia tropicalis allergen Blo t 5 in cereal and cereal-based foods consumed in the Nile Delta, Egypt

The mite Blomia tropicalis has significant prevalence worldwide. Blo t 5 is a major B. tropicalis allergen that has been associated with sensitization and allergic symptoms in many asthmatic patients. Besides house dust, contaminated foodstuffs are an important source of exposure to B. tropicalis allergens. In this study, a double sandwich enzyme-linked immunosorbent assay (ELISA) using mAb 4D4 and biotinylated mAb 4G9 was done to detect Blo t 5 allergen in different types of raw and processed foods, including wheat, corn, rice, bean, wheat and corn flour, cake, and rusk, which were collected from retail stores in the Nile Delta of Egypt. Out of 88 samples, 38 (43.2%) were positive for Blo t 5 allergen with no significant statistical difference in positivity according to food type. In positive samples, the Blo t 5 concentration ranged from 10 ng/g to 790 ng/g. This study showed that Blo t 5 should be considered as an important allergen that presents a risk to the Egyptian population and should become a routine allergen in the skin prick test to improve the management of allergic disease.

When mites attack: domestic mites are not just allergens

Domestic mite species found in indoor environments and in warm or tropical regions are well known for causing allergic disorders. However, little is known about human acariasis, in which mites invade and parasitize the human body in various tissues from the gastrointestinal tract to the lung. Here, we summarize the reported cases of human acariasis of pulmonary, intestinal, oral (anaphylaxis), urinary, otic, and vaginal systems. Because the clinical symptoms of acariasis often overlap with other disease symptoms leading to frequent misdiagnosis, we highlight the need for more attention on these infections.

Oral mite anaphylaxis caused by mite-contaminated okonomiyaki/ pancake-mix in Japan: 8 case reports and a review of 28 reported cases

BACKGROUND

Anaphylaxis after the ingestion of foods contaminated with mites has recently been recognized. 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 found 8 cases of oral mite anaphylaxis which were caused by mite-contaminated okonomiyaki-mix, a savory Japanese style pancake mix, in our hospital.

METHODS

In addition to our 8 cases, the databases of MEDLINE and ICHUSHI were systematically searched for patients with oral mite anaphylaxis in Japan.

RESULTS

Thirty-six patients including our 8 cases with oral mite anaphylaxis were identified. Thirty-four out of 36 cases (94%) ingested okonomiyaki or takoyaki, prepared at home using okonomiyaki-mix or takoyaki-mix which was previously opened and stored for months at ambient temperature. Microscopic examination of culprit mixes of 16 cases including our 1 case revealed contamination of mites such as Dermatophagoides farina (Der f) (5 cases), Tyrophagus putrescentiae (Tyr p) (4 cases), and Dermatophagoides pteronyssinus (Der p) (3 cases). The specific IgE to each mite is generally upregulated in these patients. Especially, the titers of specific IgE to Der p and Der f were more than class 2 in all cases.

CONCLUSIONS

Mite-contaminated flavored flour is the major cause of oral mite anaphylaxis in Japan.

Pancake syndrome (oral mite anaphylaxis)

Oral mite anaphylaxis is a new syndrome characterized by severe allergic manifestations occurring in atopic patients shortly after the intake of foods made with mite-contaminated wheat flour. This clinical entity, observed more frequently in tropical/subtropical environments, is more often triggered by pancakes and for that reason it has been designated "pancake syndrome". Because cooked foods are able to induce the symptoms, it has been proposed that thermoresistant allergens are involved in its production. A novel variety of this syndrome occurs during physical exercise and therefore has been named dust mite ingestion-associated exercise-induced anaphylaxis. To prevent mite proliferation and the production of anaphylaxis, it has been recommended that wheat flour be stored at low temperatures in the refrigerator.

Food allergy in Asia: how does it compare?

Asia is a populous and diverse region and potentially an important source of information on food allergy. This review aims to summarize the current literature on food allergy from this region, comparing it with western populations. A PubMed search using strategies "Food allergy AND Asia", "Food anaphylaxis AND Asia", and "Food allergy AND each Asian country" was made. Overall, 53 articles, published between 2005 and 2012, mainly written in English were reviewed. The overall prevalence of food allergy in Asia is somewhat comparable to the West. However, the types of food allergy differ in order of relevance. Shellfish is the most common food allergen from Asia, in part due to the abundance of seafood in this region. It is unique as symptoms vary widely from oral symptoms to anaphylaxis for the same individual. Data suggest that house dust mite tropomysin may be a primary sensitizer. In contrast, peanut prevalence in Asia is extremely low compared to the West for reasons not yet understood. Among young children and infants, egg and cow's milk allergy are the two most common food allergies, with prevalence data comparable to western populations. Differences also exist within Asia. Wheat allergy, though uncommon in most Asian countries, is the most common cause of anaphylaxis in Japan and Korea, and is increasing in Thailand. Current food allergy data from Asia highlights important differences between East and West, and within the Asian region. Further work is needed to provide insight on the environmental risk factors accounting for these differences.

Anaphylaxis from ingestion of mites: pancake anaphylaxis

Oral mite anaphylaxis is a new syndrome characterized by severe allergic symptoms occurring immediately after eating foods made with mite-contaminated wheat flour. This syndrome, which is more prevalent in tropical environments, is triggered more often by pancakes, and for that reason, it has been designated "the pancake syndrome." Because cooked foods are able to induce the symptoms, it has been suggested that thermoresistant allergens are involved in its pathogenesis. A variety of this syndrome can occur during physical exercise (dust mite ingestion-associated exercise-induced anaphylaxis).

Mite-induced inflammation: More than allergy

Clinical observations have suggested that there is an association of atopic conditions with hypersensitivity reactions to nonsteroidal anti-inflammatory drugs (NSAIDs). This relationship has been especially present in patients allergic to mites. This study was designed to review clinical and experimental evidence linking atopy, mite allergy, and hypersensitivity to aspirin and NSAIDs and discuss the possible mechanisms explaining this association. A review of the medical literature concerning the association of atopic diseases, mite hypersensitivity, and intolerance to NSAIDs using PubMed and other relevant articles is presented. NSAID-sensitive patients are frequently atopic and allergic to mites, and patients who develop oral mite anaphylaxis (OMA) show an increased prevalence of NSAID hypersensitivity. The study of atopic, mite-sensitive patients, who experience urticaria and angioedema when exposed to NSAIDs and patients with OMA suggests an interesting interaction between atopic allergy and disorders of leukotriene synthesis or metabolism. Various mechanisms that could be involved in this interaction are presented, including genetic factors, inhibition of cyclooxygenase-1, and other effects (not related to IgE sensitization) of mite constituents on the immune system. The association of mite hypersensitivity with aspirin/NSAIDs intolerance has been confirmed and provides additional clues to various nonallergic pathways that may contribute to the acute and chronic inflammatory process observed in atopic, mite-allergic, individuals. The clinical relevance of these observations is presently under investigation.

Allergens and their role in the allergic immune response

Allergens are recognized as the proteins that induce immunoglobulin E (IgE) responses in humans. The proteins come from a range of sources and, not surprisingly, have many different biological functions. However, the delivery of allergens to the nose is exclusively on particles, which carry a range of molecules in addition to the protein allergens. These molecules include pathogen-associated molecular patterns (PAMPs) that can alter the response. Although the response to allergens is characterized by IgE antibodies, it also includes other isotypes (IgG, IgA, and IgG4), as well as T cells. The challenge is to identify the characteristics of these exposures that favor the production of this form of response. The primary features of the exposure appear to be the delivery in particles, such as pollen grains or mite feces, containing both proteins and PAMPs, but with overall low dose. Within this model, there is a simple direct relationship between the dose of exposure to mite or grass pollen and the prevalence of IgE responses. By contrast, the highest levels of exposure to cat allergen are associated with a lower prevalence of IgE responses. Although the detailed mechanisms for this phenomenon are not clear, it appears that enhanced production of interleukin-10 in response to specific Fel d 1 peptides could influence the response. However, it is striking that the animal sources that are most clearly associated with decreased responses at high allergen dose are derived from animals from which humans evolved more recently (∼65 million years ago). Although the nose is still recognized as the primary route for sensitization to inhalant allergens, there is increasing evidence that the skin is also an important site for the generation of IgE antibody responses. By contrast, it is now evident that delivery of foreign proteins by the oral route or sublingually will favor the generation of tolerance.

[House dust mites and their allergens]

The taxonomy, anatomy, life cycle and ecology of Pyroglyphidae mites and storage mites (Acaridae, Glycyphagidae, B. tropicalis) are described. Pyroglyphidae and storage mites have similar morphologies: they are octopods, with characteristic gnathosoma and sensory hairs. Salivary glands and the mid gut produce most of the allergens excreted, which are enzymatic proteins. Biological cycles and development are similar, although fecundity is superior in storage mites compared to the Pyroglyphides. Relative humidity is the main parameter, which regulates mite development, with a higher degree of temperature and humidity required for storage mites. Bedding is the ecological niche of Pyroglyphidae, which feed on human skin. Moulds and food products are the storage mite biotope from which they spread in the dwelling. Initially considered as rural mites, storage mites are also present in urban dwellings. B. tropicalis, in tropical regions is a true domestic mite. Because of this, it is justified to denominate Pyroglyphidae "house dust mites" and storage mites "domestic mites". In addition to the respiratory allergic symptoms, the storage mites can also cause occupational contact dermatoses.

Dust mite infestation of flour samples

BACKGROUND

Ingestion of flour contaminated with dust mite may trigger severe anaphylaxis in tropical and sub-tropical regions.

AIMS

This study aimed to evaluate environmental factors that affect dust mite propagation in the tropics.

MATERIALS & METHODS

Dust mites were introduced to a variety of flour samples and incubated at two different environmental conditions.

RESULTS

It was found that dust mites populations flourished best in wheat flour compared to other varieties of flour, and at ambient temperatures with high humidity instead of the air conditioned environment.

CONCLUSION

Dust mite infestation of flour is dependent on the presence of wheat and high ambient temperature in the tropics.

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

Sensitization to Thyreophagus entomophagus, a storage mite, is uncommon and might produce occupational respiratory disorders in farmers. We present the first case of a child suffering anaphylaxis produced by ingestion of contaminated flour with Thyreophagus entomophagus.

Pancake syndrome (oral mite anaphylaxis)

Oral mite anaphylaxis is a new syndrome characterized by severe allergic manifestations occurring in atopic patients shortly after the intake of foods made with mite-contaminated wheat flour. This clinical entity, observed more frequently in tropical/subtropical environments, is more often triggered by pancakes and for that reason it has been designated "pancake syndrome". Because cooked foods are able to induce the symptoms, it has been proposed that thermoresistant allergens are involved in its production. A novel variety of this syndrome occurs during physical exercise and therefore has been named dust mite ingestion-associated exercise-induced anaphylaxis. To prevent mite proliferation and the production of anaphylaxis, it has been recommended that wheat flour be stored at low temperatures in the refrigerator.

Cross-reactivity between storage and dust mites and between mites and shrimp

Many patients have sensitivities to multiple species of storage and house dust mites. It is not clear if this is because patients have multiple sensitivities to species-specific mite allergens or if these mites share many cross-reacting allergens. Our objective was to further define the cross-allergenicity between several species of storage and house dust mites using crossed-immunoelectrophoresis (CIE), crossed-radioimmunoelectrophoresis (CRIE), immunoblotting, and ELISA. CIE and CRIE reactions revealed that storage mites shared two cross-antigenic molecules and one of these bound IgE in a serum pool from mite allergic patients. Antibody in anti-sera built to each species of mite recognized many SDS-PAGE resolved proteins of other mite species and this suggested the potential for other cross-reactive allergens. Among patient sera, IgE bound to many different proteins but few had IgE that bound to a protein with common molecular weights across the mite species and this suggested mostly species-specific allergens. Antiserum built to each mite species precipitated one protein in shrimp extracts that bound anti-Der p 10 (tropomyosin) and IgE in the serum pool. Anti-Der p 10 showed strong binding to shrimp tropomyosin but very little to any of the mite proteins. ELISA showed the mite extracts contained very little tropomyosin. The storage and dust mites investigated contain mostly species-specific allergens and very small amounts of the pan-allergen tropomyosin compared to shrimp and snail.