Vital Signs: Epinephrine September 20, 2013
Fort Worth Business Press Health Care Correspondent
The tragic death of a 13-year-old California girl who suffered anaphylactic shock and died 30 minutes after eating a Rice Krispies treat with peanut butter frosting at camp this past summer, thrust food allergies back into the news.
The girl died despite the fact that she spit out the fatal bite the moment she suspected it contained peanut butter.
She died despite the fact that her father, a medical doctor, immediately administered three epinephrine injections at the scene and an emergency ambulance took her to the nearest hospital, according to news reports.
It was the kind of accident parents fear most – the kind you know could be hiding just around the corner.
Food allergies create tremendous anxiety, but they are not nearly as prevalent, and most are not nearly as severe as people fear, Dr. Robert Rogers of Fort Worth Allergy and Asthma Associates, told physicians, nurses and other health care professionals at Cook Children’s Medical Center Sept. 10.
“Clearly, a lot of progress needs to be made in diagnosing and treating food allergies in children,” Rogers said in his Grand Rounds presentation.
But, clearly food allergies are not as common as most people believe.
“There is an enormous gap between perception and the real prevalence of food allergy,” Rogers said. “The public thinks at least a fourth of the population has food allergies, when it’s actually 2 to 3.5 percent prevalence overall and 6 percent in infants and young children.”
But, the prevalence of food allergies increased 18 percent between 1997 and 2007, and no one really knows why.
Allergic reactions range from mild skin rashes and itching to vomiting, diarrhea, stomach cramps, swelling and airway restriction, depending in part on whether you have had an earlier reaction and the amount of allergen you ingest.
What is sometimes called an allergic reaction might be a sensitivity or intolerance rather than a true allergy. Food allergy reactions are consistent and occur within minutes to several hours after each exposure to a particular food, although more than one-third of those who have food allergies are allergic to more than one food, Rogers said.
He also pointed out that a lot more people are sensitive to gluten than the number who actually have celiac disease. If you have celiac disease, eating gluten (a protein found in wheat, barley and rye) triggers a specific immune response in the small intestine that over time produces inflammation and damages the intestine.
“My practice is calming down, but a year ago everybody thought they had celiac disease and everybody wanted tested for it – (allergists) started calling it the – ‘Dr. Oz influence,’’’ Rogers said.
Most food allergies result from exposure to eight kinds of foods: eggs, milk, peanuts, tree nuts, soy, wheat, shellfish and fish.
Allergy to cow’s milk is the most common food allergy in children and the most likely to be outgrown, he noted. Children usually develop any allergic response to milk in the first year of life, and 80 percent outgrow it by age 16.
Egg allergies are second, and 68 percent of children who are allergic to eggs outgrow it by age 16. More than 70 percent of those who are allergic to eggs have mild reactions and tolerate pretty extensive exposures, Rogers added.
Most children who have egg allergies tolerate the small amounts involved in producing various vaccines like those used to immunize against measles, mumps and rubella (MMR) and the flu, and researchers are developing an egg-free flu vaccine, he said.
And, then there are peanuts.
Allergies to peanuts, tree nuts, sesame, fish and shellfish are typically life-long and can be very severe.
Some 6 percent of the population is allergic to peanuts – more than 1 percent of children, Rogers said. “Prevalence has tripled from 0.4 percent of children in 1997 to 1.4 percent in 2008. Usually the onset of symptoms is by age 2.
Severe reactions to peanuts account for about 150 deaths per year – 75 percent with first exposure, and four out of five children still react as adults, Rogers added.
Blood tests involving broad screening panels for food allergies in general are so unreliable (more than half result in false positives) that they are not used for universal screening in the absence of a history of allergic reaction, Rogers said.
For most suspected food allergies, you avoid the suspected foods then re-introduce them one at a time, but peanut allergies are so severe it is too dangerous to reintroduce them, even in small amounts, he said.
Peanut allergies are diagnosed with a blood test, in most cases after an allergic reaction.
“I don’t challenge test for peanut allergy even if it’s suspect. We do the blood test and diagnose on patient history and IgE (antibodies that attack allergens as well as infectious agents) response,” Rogers said.
EpiPens (automatic injectors that deliver a measured dose of epinephrine) should be immediately available to anyone with known food allergies as well as those allergic to the stings of bees, hornets, yellow jackets wasps and fire ants (the most common problem in Texas), Rogers said.
The 82nd Texas Legislature enacted regulations that make EpiPens readily available in schools and allow children with diagnosed allergies to stash extras with the school nurse.
Epinephrine doesn’t always work but it is the only known antidote that can stop an allergic reaction in progress.
“I think if there is any sign of reaction, give epinephrine immediately. It’s not going to hurt a child to get epinephrine,” Rogers said. “Side effects are trivial in comparison to the possible reaction. Early aggressive use of epinephrine is appropriate in anyone with a history of allergic reaction.”