Alpha-Gal Syndrome: Red Meat Is 'Just the Beginning,' Expert Says

ANAHEIM, California — Alpha-gal syndrome (AGS) is commonly described as an allergy to red meat, but that is "just the beginning," allergist and immunologist Scott P. Commins, MD, PhD, told attendees on the opening day of the American College of Allergy, Asthma, and Immunology (ACAAI) 2023 Annual Meeting.

Commins, associate chief for allergy and Immunology at the University of North Carolina at Chapel Hill, has made alpha-gal, a potentially fatal allergy, which, in the United States is tied to the bite of the Lone Star tick, his primary research focus.

Beyond red meat, "there are some people who are allergic to all things mammal," he explained. Dairy products from mammals, medical devices made from mammalian products, vaccines and medicines that contain gelatin, and even commercial products such as perfumes and cosmetics may be behind an AGS reaction.

"The derived products from pigs and cows really find their way into a lot of our day-to-day products," he said. "I try to keep an open mind about these exposures."

Physicians should also be aware that "this can happen to kids," said Commins. "It looks very similar to adults' [AGS]. They can end up in the emergency department."

He also had clinical advice about food challenges for AGS. He explained that there's more alpha-gal in beef than in other red meats (including pork, venison, and lamb) with the exception of pork kidney. Pork kidney, he said, "has the most alpha-gal that we can find in the lab."

Commins says he has stopped using beef for AGS food challenges and has switched to pork sausage patties with a high fat content microwaved in the clinic because they have less alpha-gal in general and he views them as safer.

Long Delay in Symptom Onset

AGS symptoms typically take 2-6 hours to appear after eating red meat or being exposed to mammalian products, but Commins related a story about a patient he sent home who had very mild symptoms (some lower back itching) after he had spent the day at the clinic after a pork sausage food challenge for AGS.

The patient had returned home. Eight hours after the food challenge, his wife sent Commins a picture of her husband's back, which was riddled with welts and was itching badly.

"I learned that if you're going to do these food challenges, if there is a hint of symptoms at the clinic at 6 hours, keep them in the clinic, because it may really take that long to evolve," Commins said.

One of the early signs he's discovered is palmar erythema (redness and swelling of the hands).

Research has shown that AGS has been heavily concentrated in the Southeast, where Lone Star tick populations are clustered, but research has shown that from 2017-2022, it moved up the East Coast to the central US and Upper Midwest.

"We are seeing increasing diagnoses of AGS in places that are not, perhaps, where we first thought this allergy existed," said Commins. "Stay aware," he cautioned.

The allergy is not exclusive to the US, he noted. In Europe and Australia, for example, AGS is not thought to be tied to the Lone Star tick, which doesn't inhabit those regions.

"It is a global phenomenon," Commins said.

In August, the CDC alerted physicians to emerging cases of alpha-gal allergy after an article in Morbidity and Mortality Weekly Report indicated that healthcare providers have little knowledge about the allergy. Of the 1500 healthcare providers surveyed, 42% had never heard of the syndrome, and another 35% were not confident in diagnosing or managing affected patients.

Matthew Lau, MD, an allergist with Kaiser Permanente in Honolulu, Hawaii, who listened to Commins' talk, told Medscape Medical News, "It's important to raise awareness in primary care particularly, he said, as "allergists see only a fraction of the [AGS] patients."

Allergists Can Help Raise Awareness

"Allergists have a role to alert the general community" and to drive more referrals, he said. That includes emergency departments, where physicians commonly see anaphylaxis.

Lau said he expects the incidence of AGS to increase, because global warming will likely lengthen warmer seasons and cause the geographic distribution to change.

Jay Lieberman, MD, a pediatric allergist at Le Bonheur Children's Hospital in Memphis, Tennessee, told Medscape Medical News, "There's still a lot of confusion, and hearing from an expert like Dr Commins helps tease out the not-obvious things about patients who are having more mild symptoms," such as from allergy to dairy or medicines or vaccines that contain gelatin.

As a pediatric allergist, Lieberman says he sees less alpha-gal than his colleagues, but, he said, "On the adult side in Tennessee, it's rampant."

Commins, Lieberman, and Lau report no relevant financial relationships.

Marcia Frellick is a freelance journalist based in Chicago. She has previously written for the Chicago Tribune, Science News, and Nurse.com, and was an editor at the Chicago Sun-Times, the Cincinnati Enquirer, and the St. Cloud (Minnesota) Times. Follow her on Twitter at @MLfrellick