Know the urban myths that compromise allergy care
AT 2014 AAAAI ANNUAL MEETING
SAN DIEGO – There’s no such thing as a hypoallergenic dog. Blood tests for sale on the Internet won’t identify a child’s allergies. And parents don’t have to wait until a child is 1, 2 or 3 years of age to introduce dietary milk, eggs, or nuts.
These are some of the facts that physicians need to know in order to counter common myths about allergy, Dr. David R. Stukus said at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
Patients aren’t the only ones who need enlightening. Too many physicians still believe some of the myths listed below, said Dr. Stukus of the department of pediatrics at Nationwide Children’s Hospital and Ohio State University, Columbus:
• Hypoallergenic pets: "There’s a lot of false advertising" by companies marketing supposedly hypoallergenic pets, some selling cats for $7,000-$28,000 or dogs for $16,000, he said. While some of these animals have been bred to produce fewer major allergens from their saliva, sebaceous glands, or perianal glands, they still produce minor allergens that cause clinical symptoms in sensitized people.
• Blood testing: Allergen-specific serum IgE testing is not a reliable screen for allergy, and often leads to misinterpretation and false-positive results – which in turn lead to diagnostic confusion and unnecessarily eliminating foods from a diet. Patients can purchase kits on the Internet for $49.95 that purport to test blood for 10 food, animal, environmental, and inhalant allergens, the results of which are sent back to patients for them to interpret or to ask their doctors to interpret.
Other blood-test kits selling for $450 on the Internet claim to test for IgG antibodies toward foods and additives, even thought IgG antibodies indicate exposure to products, not allergy, and may be a marker for food tolerance, not intolerance, Dr. Stukus said. A physician in the audience said that some allergists in his community are doing these IgG antibody tests, "so we have to watch ourselves, too," he said.
• No milk, eggs, or nuts for babies: Changes in recommendations over the years have contributed to the myth that highly allergenic food such as milk, eggs, or nuts should be avoided by infants until ages 1, 2, or 3 years. The most current recommendations from the American Academy of Pediatrics say that there’s no evidence to support avoiding highly allergenic foods past 4-6 months of age (Pediatrics 2008;121:183-91).
Some evidence is emerging from recent trials that early introduction of highly allergenic foods may promote tolerance, but "if they have a sibling with a peanut allergy, it makes sense to do IgE testing before peanut introduction," he said.
• Artificial dye: Despite controversy around artificial food coloring since the 1950s and around food additives in the 1970s, there is no scientific evidence to support a link between exposure to artificial dye or coloring and IgE-mediated allergic reactions, and there are no skin test extracts or serum-specific IgE tests to test for artificial dye allergy. On the contrary, many studies have found no associations.
There is some evidence, however, that an additive-free diet may improve symptoms of attention-deficit/hyperactivity disorder in a small subset of children (Clin. Pediatr. 2011;50:279-93) And rare cases of anaphylaxis have been reported in reaction to carmine, a natural red coloring derived from dried insects that is commonly used in cosmetics, but not in reaction to artificial dye.
• Egg in vaccines: Dr. Stukus handled a recent consultation in which "they were refusing to give MMR vaccine to someone with egg allergy. So, there is still a lot of confusion over this," he said.
MMR vaccine is safe for anyone with a history of egg allergy, with no testing or allergy referral required, he said. Influenza vaccine also can be given safely to egg-allergic patients, dozens of trials and guidelines conclude, with some differences in recommendations, he said. The Joint Council of Allergy, Asthma, and Immunology says there’s no need for a waiting period or referral to an allergy specialist, while the Centers for Disease Control and Prevention and the American Academy of Pediatrics recommend 30 minutes of observation for egg-allergic patients who receive influenza vaccine and referral to an allergist if there’s a history of anaphylaxis to egg. Egg-free influenza vaccine is a relatively new alternative.
Vaccine for yellow fever or rabies is contraindicated in patients with allergy to egg, but there are tests and procedures that may allow these vaccinations in a graded manner in some patients. Egg-free alternatives to rabies vaccine also are an alternative. Gelatin in both of these vaccines can cause allergic reactions, so evaluate gelatin-hypersensitive patients before vaccinating.
