Conference Coverage
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.
Wikimedia Commons/Pete Souza/Public Domain
"First dog" Bo Obama is said to be less allergenic than some other breeds.
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.
Dr. David Stukus
• 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.
• Shellfish, iodine, and radiocontrast media: Surveys suggest that a majority of radiologists and cardiologists routinely ask patients about shellfish allergy before administering iodinated contrast media, even though iodine is not an allergen, Dr. Stukus said. This myth seems to have originated from a 1975 study in which patients with any kind of reported allergy were twice as likely to react to contrast media ( Am. J. Roentgenol. Radium. Ther. Nucl. Med. 1975;124:145-52 ). Reports of seafood allergy in 15% of patients were associated with reaction to contrast media, but so were reported egg, milk, or chocolate allergy, each in 15% of patients. "Have any of you ever asked patients if they have a chocolate allergy before irradiating them?" Dr. Stukus asked.
Reactions to radiocontrast media with high osmolality agents are common, however, affecting 5%-12% of patients, with elevated risk in patients with atopy. Premedication regimens for patients with a previous reaction to radiocontrast media can lower the risk to less than 1%.
• Skin testing: The idea that skin testing is unreliable until 2, 3, or 5 years of age is sheer myth, but an ongoing one. "I had one of my colleagues say this to me 2 weeks ago," Dr. Stukus said. Skin testing is reliable at any age and can accurately assess for the presence of specific IgE, he said.
• Penicillin allergy: Adverse reactions to antibiotics are very common, but true allergic reactions are uncommon. Approximately 10% of people in general say they are allergic to penicillin, but fewer than 10% of those will have a positive skin test or symptoms if challenged. "If patients get labeled allergic" to penicillin "on their chart, that follows them forever" and makes them more likely to use less-effective, more-toxic, costlier antibiotic alternatives, Dr. Stukus said. "We can improve their lives by proving they don’t have it and taking this label off their chart."
• Gluten: Eating gluten "is currently being blamed for the ails of humanity," largely driven by companies with products to sell – so be prepared to talk about this with patients with self-diagnosed gluten allergy, Dr. Stukus said. IgE-mediated hypersensitivity reactions can occur toward wheat, rye, or barley, but not to gluten. Celiac disease is an autoimmune condition (not IgE-mediated hypersensitivity) that improves with a gluten-free diet. IgE-mediated hypersensitivity to gluten is very uncommon, but patients more commonly report having "gluten sensitivity" and GI symptoms after eating foods with gluten. That’s a poorly defined condition that’s hard to prove. A double-blind, placebo-controlled challenge is the only available method of diagnosing gluten sensitivity.
• Mold: Mold is everywhere and can cause real disease in susceptible persons, but mycotoxins rarely cause disease unless ingested in large quantities. Most health problems attributed to mold exposure are exaggerated, with no scientific basis or supportive evidence, Dr. Stukus said. But "hysteria" around mold has been a boon to some lawyers and companies that sell air purifiers and other detoxification equipment. Know your approach to identifying mold allergy, and be straightforward with patients, he advised.
Dr. Stukus reported having no financial disclosures.
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