First came the itching — hives so maddening they made Suzanne Keithley-Myers want to claw her flesh. Then came waves of stomach pain so dizzying and disorienting they made her "kind of afraid for my life."
The 45-year-old nurse couldn't explain her body's breakdown. She suspected it was tied to ticks that had bitten her during a June mushroom hunting trip in the woods near Aurora, Minn., but this didn't seem like a typical tick reaction.
On a hunch, she Googled "meat allergy" and found something that seemed like a perfect fit — a rare, potentially severe allergy to "alpha-gal," a sugar found in red meat, triggered by a bite from the lone star tick.
Adding to the mystery: the lone star tick isn't supposed to be in Minnesota. Yet, in the last couple years at least two dozen people in the northern part of the state have suddenly become severely allergic to red meat.
Dr. Alaaddin Kandeel, an allergist at Essentia Health in Duluth who saw Keithley-Myers, said he's diagnosed the same allergy in 18 patients, including 10 from northeast Minnesota and eight from northwest Wisconsin.
"And I've seen this at least one patient a month with this allergy," he said. "I've had patients who passed out as a result of this, and sometimes it can be fatal as well."
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Dr. Chris Cleveland, an allergist at Sanford Health in Fargo, N.D., has seen similar symptoms in a handful of Minnesota patients he treated in Bemidji and Thief River Falls.
"Waking up often in the middle of the night, usually four to six hours after they've been done with their meal, and have very intense itching to their palms and the soles of their feet," he said.
It can spread across nearly the entire body, even swelling the tongue and throat, he added.
Nationally, the allergy has largely been concentrated in the southeastern U.S., where scientists have linked it to the lone star tick.
Diagnoses of the allergy have exploded, from a couple dozen people when it was first identified about seven years ago, to several thousand today.
In Minnesota, it's not clear what kind of tick is triggering the trouble. The lone star tick's range currently stops just below the Iowa border.
"We get sporadic reports of lone star ticks, but we don't know of any established populations because when we've gone out and done our routine tick surveillance, what we really find are wood ticks ... and then those black legged ticks, or the deer ticks," said Elizabeth Schiffman, an epidemiologist at the Minnesota Department of Health.
In Minnesota, tick-borne diseases are reportable by law. So every time a provider diagnoses a case of Lyme disease, for example, they send that information to the Department of Health. But allergies, like the alpha-gal allergy, are not reportable conditions, Schiffman said.
So the state doesn't know if cases of alpha-gal allergies are on the rise.
Researchers, though, are starting to think there could be something other than the lone star tick causing the allergy.
"We have colleagues who've reported patients from Sweden and Australia and central Europe and now even in Japan and they have very different ticks. So I don't think it's by any stretch limited to one species of tick," said Scott Commins, an associate professor of medicine and pediatrics at the University of North Carolina and one of the researchers who first identified the alpha-gal allergy.
Researchers may have been guilty of pigeonholing the allergy on the lone star tick, he said, adding that people who've been bitten by different kinds of ticks are now also contracting the allergy.
He's now conducting experiments to try to find out exactly what in the tick bite is triggering the allergy.
Here's the leading hypothesis. A tick feasts on an animal like a deer, or a mouse, that carries the alpha-gal carbohydrate. Later that tick bites a human, and transfers something in its saliva that triggers an allergic reaction.
The deer tick, which carries Lyme disease, could probably cause the alpha-gal allergy in that manner, said Commins.
"I don't want to alarm people, but I do feel that there probably is legitimate concern that this may be something that is the tip of the iceberg (in Minnesota) with the cases that you have at the moment.
Genetic factors likely determine whether someone has an allergic response. Hundreds of thousands of people get tick bites, he said, and only a very small fraction end up with the alpha-gal meat allergy.
Still, there are likely people who already have the allergy but don't know it, said Commins. Often it results in painful stomach cramps, but not itchy hives. And because the reaction occurs several hours after eating, he said it's hard for patients to put the connection together.
"It's really hard for people to pinpoint it," said Heather Fealy, 44, of Orr, Minn. She was diagnosed with the allergy last summer after being bitten by a tick in April, and one morning waking up covered in hives.
Now she tries to educate others about it. She recently met someone at the grocery store, shopping for veggie burgers.
"She had never heard of the allergy, but she said she hasn't been able to eat beef for quite a few years. She gets real bad stomach pain."
Kandeel said his advice for people who think maybe they have the allergy is to keep a food journal, to see if their symptoms are related to any specific food, and then seek further help for evaluation.
Commins said people who suspect they have the allergy must avoid beef and pork fat in recipes and foods, and perhaps dairy as well.
"We know that in some patients the allergy fades over time. There are others where this appears to be long-lasting," he added. "The issue is we don't know what defines the groups or how to predict who will end up in each group at the outset. It may depend on further tick bites."
For Keithley-Myers, it's been about six months since she was diagnosed with the alpha-gal allergy.
She's had to stop eating the meat her husband hunts. She's also had to give up cheese and be vigilant for animal byproducts like gelatin that can also spark a reaction.
"It makes things really hard," she said. I can't go to pot lucks and enjoy myself," she said. "I can't host the same way that I used to. I spent a few months really grieving it. It was a huge change."