Dust mites are one of the most common triggers of allergic conditions such as in the conditions of hay fever (i.e., allergic rhinitis), allergic asthma, atopic dermatitis (i.e., eczema), and/or food allergies. Dust mites are microscopic insects that live in house dust and on human skin scales. The allergens are excreted in their droppings which then become aerosolized. When sensitized individuals are exposed to these substances in the air, they develop bothersome allergy symptoms such as nasal congestion, runny nose, sneezing, post-nasal drip, itchy nose, itchy eyes, watery eyes, redness of the eyes, fatigue, sinus pressure, sinus headaches, chest tightness, coughing, wheezing and/or shortness of breath.
Although uncommon, some individuals who are sensitive to mites can also develop severe allergic symptoms immediately after eating foods prepared with wheat flour contaminated with various species of mites. This syndrome is designated as oral mite anaphylaxis (OMA) or “pancake syndrome.” It is called pancake syndrome because the most common food to cause such a severe allergic reaction are pancakes.
This condition is more commonly reported from tropical and subtropical regions, probably because in those regions there are environmental conditions favorable for mite reproduction, especially higher temperatures and relative humidities, for longer periods of time. The majority of subjects are adolescents and young adults, although oral mite anaphylaxis can occur in children. In most cases, there is a previous history of atopy where individuals have a history of allergic rhinitis, asthma, atopic dermatitis, and/or food allergies. The allergic individual tends to develop symptoms between 10 minutes and 4 hours after eating the mite-infested food.
The types of mites identified in the pancake syndrome are generally either dust mites or storage mites. The most common dust mites are Dermatophagoides farinae and Dermatophagoides pteronyssinus. The most common storage mites include Blomia tropicalis, Blomia freeman, and Suidasia pontifica, Aleuroglyphus ovatus, Thyreophagus entomophagus, Lepidoglyphus destructor, and Tyrophagus putrescentiae.
The typical symptoms of the pancake syndrome may include shortness of breath, laryngeal and/or facial angioedema (swelling of the vocal cords and/or face which may result in a blocked airway), wheezing, coughing, runny nose, difficulty swallowing, urticaria (i.e., hives), abdominal cramping, and/or redness of the eyes. The clinical presentation may be very severe, such as anaphylaxis, which can lead to hospitalization in the intensive care unit due to laryngeal edema and acute respiratory failure.
Implicated foods usually contain wheat flour, and may include foods such as pancakes, bread, pasta, and pizza. As mentioned previously, pancakes are the most frequently involved food. It is important to note that the allergens causing oral mite anaphylaxis are resistant to heat. Thus, the reactions to the mite-contaminated foods can be induced by well-cooked foods. This is different than what is seen in oral allergy syndrome (i.e., pollen food allergy syndrome). In oral allergy syndrome, well-cooked foods denature the allergen, so individuals can eat well-cooked fresh fruits and/or vegetables without symptoms. In oral mite anaphylaxis, individuals will still develop symptoms even if the mite-infested food is well-cooked. Of note, allergy skin tests with mite-contaminated wheat flour, both before and after it is cooked, will also be positive.
In addition to oral mite anaphylaxis being more common in dust mite sensitive individuals with allergic rhinitis, asthma, atopic dermatitis and/or food allergies, it is also more commonly seen in patients with aspirin and/or NSAID (i.e., nonsteroidal ant-inflammatory drug) hypersensitivity. These patients generally develop hives and/or swelling when they consume aspirin or NSAIDs. Genetic factors are thought to be responsible for this association.
There is also a variant of oral mite anaphylaxis which only occurs after eating mite-infested food followed shortly thereafter by exercise. If the person does not exercise, no symptoms occur. If the person only eats the mite-contaminated food, no symptoms occur. It is the consumption of the mite-contaminated food followed by exercise within a relatively short period of time that will cause the allergic symptoms we have been referring to throughout this blog. This variant of the pancake syndrome has been named dust mite ingestion-associated exercise-induced anaphylaxis.
Risk Factors for Oral Mite Anaphylaxis:
1. Mite allergy
2. History of atopic disease (i.e., allergic rhinitis, asthma, atopic dermatitis)
3. Aspirin/NSAIDs hypersensitivity (i.e., hives/swelling from aspirin/NSAIDs)
4. Consumption of foods prepared with mite-contaminated wheat flour
5. Consumption of more than 1 mg. of mite allergen (>500 mites/gram of flour)
Diagnosis of Oral Mite Anaphylaxis:
1. Previous history of rhinitis, asthma, atopic dermatitis, and/or food allergies
2. Allergic symptoms occur after eating foods prepared with wheat flour
3. Positive skin test with the suspected flour
4. Negative skin tests to wheat and to uncontaminated flour
5. Mite allergens present in flour
6. Identification of mites via a microscope in suspected flour
7. Ability to eat uncontaminated flour without symptoms
8. Aspirin/NSAIDs hypersensitivity in some patients
9. Exercise-induced anaphylaxis with mite-contaminated food in some patients
It is known that mites can grow in closed packages of wheat flour at room temperature. It is also known that exposure to low temperatures inhibits mite proliferation. In order to try to prevent oral mite anaphylaxis, is recommended to store flour in sealed containers in the refrigerator.
The board certified allergy specialists at Black & Kletz Allergy have been treating mite allergies in children and adults in the Washington, DC, Northern Virginia, and Maryland metropolitan area for more than half a century. Black & Kletz Allergy provides on-site parking at all of their convenient locations in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA. The Washington, DC and McLean, VA locations are Metro accessible and there is a complementary shuttle that runs between our McLean office and the Spring Hill metro station on the silver line. Please call any of our offices to schedule an appointment for your allergy, asthma, or immunology needs. Alternatively, please click Request an Appointment and we will respond within 24 hours on the next business day. We strive to provide our patients with the highest quality and most up-to-date allergy diagnostic tests and treatments in a pleasant, caring, and professional environment.