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Approximately 11 million Americans live with food allergies. Peanut allergy is the second most common food allergy (seafood being the most common) in children although the most significant, due to the potentially life threatening nature of the reaction. It occurs in approximately 1 in 50 children and is the most likely food to cause anaphylaxis resulting in death. Estimates indicate one death for every 200 episodes of anaphylaxis. Heredity seems to be the prime reason some people have allergies and others do not. In the individual with a food allergy, the immune system produces increased amounts of immunoglobulin E antibody, or IgE. When these antibodies battle with food allergens, histamine and other chemicals are released as part of the body's immune reaction to these substances. These chemicals cause blood vessels to widen, smooth muscles to contract and affected skin areas to become red, itchy and swollen -in effect, causing an allergic response. Food allergy most commonly becomes evident during infancy and preschool years, usually presenting as eczema, hives, vomiting, diarrhea, failure to thrive and anaphylaxis. Severe reactions can occur with even trace amounts of the food allergen, especially with peanuts. Serious reactions can also occur from skin contact, touching the eyes, and through inhalation of food particles. In young children, although the initial contact with the allergen may be on the hands or arms, the reaction can spread to other parts of the body through scratching and rubbing of the face and eyes. Allergists test for diagnosis of allergies through skin and blood testing. With skin testing, the physician places a diluted amount of the extract of the suspected food on the skin through a puncture or scratch. Within 15 to 20 minutes, a positive reaction typically appears as a raised bump surrounded by redness. Currently, there are two types of blood tests: the radioallergosorbent test (commonly known as RAST) and ImmunoCAP, where the food allergen does not need to be introduced to the body for testing. If properly performed and interpreted, skin test and/or blood testing to foods are reliable and good screening tests for food allergy; nonetheless, true confirmation of a suspected food allergy requires an appropriately designed and monitored oral challenge.
Most individuals who have had an allergic reaction to
food ate something they thought was safe. And yet, the majority
of patients
and their
parents do not have a written plan from their doctor for preventing
and treating
reactions. This can be a costly mistake. 1 “Peanut Allergy,” Allergy
Unit, Royal Prince Alfred Hospital, Australia, |
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There
is no cure for food allergy. Strict avoidance of the allergy-causing
food is the most secure methodology for preventing a reaction.
Patients should be on guard for hidden ingredients in unsuspected
foods such
as in candy, baked goods, trail mixes, sauces, desserts or
gravies. (see
Precautions) In the event of an adverse reaction, studies have
shown that early administration of epinephrine (EpiPen®),
upon first presentation of symptoms, is the key to a patient's
avoidance and survival
of anaphylactic
shock.