Allergist Dr. Phillip Lieberman has been tracking anaphylaxis in adults at the University of Tennessee allergy clinic for decades, trying to solve the riddle of “idiopathic” anaphylaxis. That’s a disturbing diagnosis to get as a patient: a severe allergic reaction, with no identified cause – and therefore no clue as to what to avoid.
In a report on adult anaphylaxis cases at the Memphis clinic dating up to 2006, 59 percent were labeled as “idiopathic.” But in a new report on 222 such patients from 2006 to present, Lieberman and his colleagues were able to reduce the rate of “undetermined” anaphylaxis cases to 34 percent, an impressive drop of 25 percentage points.
The big difference? Lieberman revealed in a case report presented at the 2018 AAAAI/WAO congress that his team was able to confirm alpha-gal or red meat allergy in a majority of those patients. The first study on this allergy was only published in 2009, but it is becoming an increasingly common allergy that’s getting better recognition.
The mechanism of alpha-gal allergy is unusual. It develops after a bite from a Lone Star tick (Amblyomma americanum) triggers a person’s immune system to begin producing IgE antibodies to alpha-gal, a sugar found in meat such as beef, lamb, venison and pork.
“We just happen to be in the epicenter of the Lone Star tick distribution in the United States out in Memphis,” Lieberman said during a press conference at the Orlando meeting. “We’re surrounded by rural community, with a lot of hunters and fishers and a lot of forest exposure. So it has now become the single most common cause of anaphylaxis [in adults] in this area.” In adults, particularly women, at Lieberman’s clinic, it’s now a more common anaphylaxis trigger than traditional IgE-mediated food allergy or drugs.
Tennessee is far from the only state affected. In previous reporting, Allergic Living has been told that alpha-gal allergy has effectively “taken over” the adult side of food allergy practices in Tennessee but also Virginia, North Carolina, Arkansas and Missouri. As the Lone Star tick roams farther north, many cases are now being reported in Ohio, New York, New Jersey and even Minnesota.
Lieberman says identifying alpa-gal as the culprit behind these idiopathic cases has been life-changing for his patients, some of whom were suffering “as many as 15 to 24 reactions, because we couldn’t tell them what to avoid.”
Complicating diagnosis is the fact that alpha-gal allergy symptoms are delayed in onset. A person with this allergy may eat dinner, go to bed and awaken five or six hours later with severe symptoms of anaphylaxis – and go to hospital, without connecting the dots to a meal consumed much earlier.
Watch for: Allergic Living will have a full report on the rise of red meat allergy in its Summer 2018 print magazine.