Red meat fans beware. The Centers for Disease Control and Prevention warns that alpha-gal syndrome (AGS) — a tick-borne illness that causes a red meat allergy — is an emerging public health concern.
There have been more than 90,000 suspected cases documented between 2017 and 2022, yet nearly half of clinicians have never heard of the condition, according to a pair of CDC reports released on Thursday.
Because many providers aren’t aware of AGS, which also requires a diagnostic test, the agency estimates that as many as 450,000 people may have been affected since 2010.
Scientists first connected the dots between red meat allergies and tick bites more than a decade ago, when they identified patients who got allergic reactions such as hives or anaphylaxis after eating beef or pork. Most had been bitten by Lone Star ticks. Now, doctors’ understanding of these allergies has evolved.
“What’s new is that we have patients who really just have GI symptoms,” explains Dr. Sarah McGill, a gastroenterologist at the University of North Carolina. McGill says some alpha-gal syndrome, or AGS, patients feel sick to their stomachs after they eat red meat, but never develop more typical allergic symptoms, such as a rash, swelling or trouble breathing.
McGill has co-authored new guidance for the American Gastroenterological Association to raise awareness about the GI-only onset. She has diagnosed AGS in people who experience abdominal pain, diarrhea, nausea or vomiting about 2 to 6 hours after eating red meat.
That’s exactly what happened to Randy Rayborn, 72, who lives in a rural community in Caswell County, North Carolina. “I figured it was food-poisoning,” Rayborn recalls thinking after his first alpha-gal attack in the fall of 2019.
“I woke up in the middle of the night with severe pain and nausea. I had to rush to the restroom,” Rayborn recalls. He describes the episode as “the most violent upheaval” he’d ever experienced.
Deer and ticks are prevalent near Rayborn’s home. He recalls pulling several ticks off his body in the months before his illness began, but he didn’t realize the bites had triggered the illness. Nor did he imagine that the hamburgers or bacon he’d eaten had anything to do with it.
When he had a similar attack a few weeks later, he went to see his doctor, who referred him to McGill. A blood test showed he had Immunoglobin E, or IgE antibodies to alpha-gal, the sugar molecule that he was exposed to from the tick bites, suggesting he was positive for the allergy. “I’d never heard of it,” Rayborn says, so he was very surprised.
McGill advised him to eliminate all red meat from his diet. “I miss bacon, I miss hamburgers, ” Rayborn says. But after suffering through such painful episodes, “I don’t miss them that much,” he says. He remains symptom-free after several years on the diet.
Alpha-gal is a sugar molecule found in most mammals, including cows, lambs and pigs. It can also be found in the saliva of ticks. Humans don’t make alpha-gal, so it’s foreign to us, explains Dr. Scott Commins, an allergist at the University of North Carolina in Chapel Hill. When tick saliva goes through a person’s skin and transmits alpha-gal it can be a potent inflammation trigger.
