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As Tick Bites Rise, So Do Meat Allergies

lone star tick

Aug. 3, 2018 -- Barbara Newman didn’t think much about it when she first noticed a large tick in her hair one day after hiking in September 2012. She had several bites on her arms from tiny tick nymphs, too. But she hikes frequently and works for the Jefferson County Health Department in Alabama and knows how to remove them. So she did, and she put some cream on her arms and carried on.

Newman and her husband ate roast beef for lunch the next day, and the following night, her husband made bell peppers stuffed with ground beef for dinner. About 8 hours after that, Newman’s scalp started to itch so badly, it woke her up in the middle of the night.

“My head felt like it was on fire, and when I got up and looked in the mirror, my lips were so swollen. I looked like Daffy Duck,” she recalls. “I got up to take some Benadryl and figured I would go to the doctor in the morning. But it kept getting worse and worse, so I went to the ER.”

Emergency crews wasted no time when she walked in, immediately recognizing the symptoms of anaphylaxis -- a severe allergic reaction that can be life-threatening. They laid her on a gurney and gave her epinephrine as quickly as possible.

“The whole time I remember thinking, ‘Whoa. How did this happen?’ ” Newman says.

She followed up with an allergist, and testing revealed high levels of resistance to beef and pork -- even though Newman, who was then 53, had been eating meat her entire life. “The doctor told me he knew of a researcher looking into this phenomenon where if you are bitten by a tick, you can develop this bad allergic reaction to mammalian meat, so he wanted to do a more specific test,” Newman said.

Further testing revealed she did indeed have high levels of alpha-gal in her blood, meaning she had been bitten by a Lone Star tick, which triggered the anaphylactic reaction to meat.

“The time between when I ate the meat and the allergic reaction was about 8 hours, and I feel like it could have been hard to correlate the two things,” Newman says. “I feel so lucky my doctor knew about this.”

The CDC says tick, mosquito, and flea bites tripled in the United States between 2004 and 2016, and Lone Star ticks -- named for the white shape on the back of adult females that resembles the shape of Texas -- have increased in “distribution, range and abundance” in the last 20 to 30 years. They can now be found as far north as Maine and as far west as Texas and Oklahoma, while they’re normally found across the Eastern, Southeastern, and South-Central states.

Researchers have discovered that a Lone Star tick bite can make some people react to the alpha-gal carbohydrate, a complex sugar found in red meat like beef and pork.

Understanding the Link Between Meat Allergies and Tick Bites

Alpha-gal syndrome isn’t listed on the CDC website as a tick-borne disease. Scott Commins MD, PhD, an associate professor of medicine and pediatrics at the University of North Carolina, says that makes sense, because this is more of an allergy than a disease. He is part of the team that first discovered that the Lone Star tick can cause a meat allergy. He did that while working at the University of Virginia with Thomas A.E. Platts-Mills, MD, the doctor who discovered alpha-gal was the cause of allergic reactions to a cancer drug.

“We had a couple of patients who described this delayed reaction to red meat,” Commins says. “At first we were the only center reporting this, and there was a healthy amount of skepticism. But over time, an awareness of this allergy began to grow.”

Platts-Mills published his first paper on alpha-gal in 2008, and he and Commins published about the link to a meat allergy in 2009, although they say they’ve have heard of cases as far back as the 1970s. And around the same time their research was beginning, Platts-Mills himself got the meat allergy after being bitten by a number of ticks during a 5-hour hike in Virginia. Three months later, he ate two lamb chops and woke up 6 hours later in the middle of the night covered in hives.

“I think in part it shows how common this is and that the kind of people who get it spend hours on a mountain walking off trail,” Platts-Mills says. In fact, a crowdsourcing website has almost 3,000 reports from people around the world who say it happened to them.

Now, a study published last week in Annals of Allergy, Asthma and Immunology reports the alpha-gal meat allergy was the most common known cause of anaphylaxis at the University of Tennessee Health Science Center between 2006 and 2016 -- accounting for 33% of 218 cases reviewed.

Debendra Pattanaik, MD, lead author of the study and an associate professor of medicine at the University of Tennessee Health Science Center in Memphis, says an increase in the Lone Star tick population since 2006 is the likely cause of the jump in cases, as is a better understanding in the medical community that tick bites may cause the alpha-gal allergy.

“Our research clearly identified alpha-gal as the cause of anaphylaxis in the majority of cases where the cause was detected. Food allergies were the second leading cause, accounting for 24%,” Pattanaik says.

In previous studies at the center, researchers often couldn’t identify the source of severe allergic reactions. “When we did the same review in 1993, and again in 2006, we had a great many cases where the cause of the anaphylaxis couldn't be identified,” Pattanaik says. The number of unexplained cases is now at 35%, down from 59% in 2006, he says.

Researchers acknowledge that Tennessee has a big population of Lone Star ticks, which likely influenced the numbers of alpha-gal cases they identified. Still, they point out that while the Lone Star tick is mostly found in the Southeastern U.S., cases are being reported nationwide.

Laura Stirling can attest to that. The Severna Park, MD, resident ate Italian sausage for dinner one night in 2017 and woke up 6 hours later covered head to toe in hives. They were itchy, painful, and had nearly swollen one eye shut. She was also dizzy, lightheaded, and nauseated.

That morning, she went to her primary care doctor, who had no idea what was going on and referred her to an allergist who asked if she’d been bitten by a tick. She had, about 3 weeks earlier. The 51-year-old’s blood test came back with an alpha-gal number of 89. Normal is below 0.35.

“I was lucky I never stopped breathing. In my reactions, hives, upset stomach, and lightheadedness are the signs,” Stirling says. “The whole concept of this is totally crazy, but being able to control it makes it just fine. I have not had another reaction since I was told a year ago to stop eating red meat.”

What We Know About Alpha-Gal

Researchers still don’t know the molecular trigger for the allergic response. Platts-Mills, the UVA professor, says it can happen anywhere from 2 weeks to 3 months after a tick bite when someone eats any red meat, including beef, pork, and venison.

The allergy is best diagnosed with a blood test checking a person’s sensitization to these meats. It can cause hives, itching, swelling, difficulty breathing, and a variety of digestive symptoms, including cramping, pain, and nausea. The National Institutes of Health describes an anaphylactic reaction as one that involves two or more organs. It can be stopped with epinephrine.

Commins, the UNC professor, says cases often happen to people in their 40s or 50s, but he’s published research on nearly 50 cases in children, too. This food allergy does have one big difference from most others: Unlike other food allergies that happen within seconds or minutes of having a certain food, symptoms of allergic reactions to alpha-gal aren’t seen for 3 to 6 or even 8 hours.

“We think the timing of the allergy has to do with the fat content of meat and that fat gets absorbed slowly into the bloodstream,” Commins says. “We are actively investigating that now.”

Researchers are also trying to figure out what it is about ticks that causes this reaction. They’re looking at deer blood, tick saliva, and bacteria from ticks as possible causes, and there’s now research around the world, with cases of meat allergies resulting from tick bites coming from Australia and Europe, although as a result of different kinds of ticks. Commins says once this is better understood, there’s hope of someday having a treatment that could desensitize people through allergy shots -- like what’s available for bee or wasp venom.

In the meantime, researchers say it’s important that medical professionals other than allergists know about this condition. They say doctors need to understand that abdominal pain is a key marker of this allergy and that symptoms are delayed.

“Allergists are aware, but I’m not sure about ER and primary care doctors,” says Pattanaik, the lead author of last week’s alpha-gal meat allergy study. “Many doctors think allergic reactions happen right away since that happens with milk and peanuts. I think it is even hard for many patients to make the connection when it’s several hours later, so we need to spread the knowledge that you can have this reaction to meat you ate hours before.”

Commins says it’s also important to educate doctors that this allergy often has symptoms at night -- likely because many people eat red meat for dinner. “Typically these patients often have nighttime reactions. They have a history of being outdoorsy. Sometimes they even know they had a recent bad tick bite,” Commins says. “Even though it seems remote, an important question for doctors to ask is, ‘What did you eat, the meal before your symptoms started?’ ”

Living Without Meat

Many who get the alpha-gal allergy have it not only to meat, but to all animal products, including dairy. That’s happened to Stirling. Her symptoms have reappeared with dairy -- she even reacted once to organic soap made with goats’ milk. She now checks all food and product labels, asks restaurants to cook her food in separate pans if possible to avoid cross-contamination, and she frequently calls manufacturers to see if they’re using animal products as seasoning or a minor ingredient.

“It is a crazy allergy, but I don’t let this restrict my life,” the real estate agent says. “I just got back from Greece. I travel. I go out to dinner. I just ask a lot of questions.”

A year after her reaction, Stirling’s alpha-gal numbers have dropped 30%. But when her allergist encouraged her to try a small slice of cheese, she still got a stomachache within 30 minutes. So she’s continuing to avoid all animal-based products and doing what she can to educate people about the condition along the way.

“I’ve had chefs actually come to a restaurant table to ask questions because they want to learn more about this,” Stirling says. “I really feel like a lot of people don’t get it. I think they feel like it isn’t a real thing, and that is extremely dangerous. It was very overwhelming in the beginning and terrifying, too, because I was always wondering if I would have a reaction.

“But I have educated myself, and now I have it under control. You can live with this. It’s tough, but it’s not the end of the world.”

Newman, the Alabaman who got the allergy in 2012, agrees. She’s avoided beef and pork for 6 years now and says she does just fine with a diet that relies on turkey bacon, chicken, and fish for protein. She says that has made it easy to maintain a healthy weight, and food has become cheaper. And while her bloodwork last year also indicated her alpha-gal levels have gone down and her allergist says she could try to start eating meat again, she says she’s not interested. 

“No way. I’m off meat. My reaction was so bad. I’m not going to do that again,” says Newman, who’s now 59. “I’ve lived without meat just fine, and I’m outside a lot, so nope -- I’m not taking that chance again.”

WebMD Article Reviewed by Michael W. Smith, MD on August 06, 2018

Sources

Scott Commins, MD, associate professor of medicine, University of North Carolina, Chapel Hill.

Barbara Newman, Birmingham, AL.

Debendra Pattanaik, MD, associate professor of medicine, University of Tennessee, Memphis.

Thomas A.E. Platts-Mills, MD, professor of medicine and microbiology, University of Virginia, Charlottesville.

Laura Stirling, Severna Park, MD.

Journal of Allergy and Clinical Immunology: “Red meat allergy in Sweden: Association with tick sensitization and B-negative blood groups.”

Pediatrics: “Galactose-α-1,3-galactose and delayed anaphylaxis, angioedema, and urticaria in children.”

Annals of Allergy, Asthma & Immunology: “The changing face of anaphylaxis in adults and adolescents.”

Current Opinion in Allergy and Clinical Immunology: “Understanding the mechanisms of anaphylaxis.”

Journal of Allergy and Clinical Immunology: “The alpha-gal story: Lessons learned from connecting the dots.”

CDC: “Tickborne Diseases of the United States,” “Illnesses from Mosquito, Tick, and Flea Bites Increasing in the US,” “STARI or Lyme?”

Zeemaps: “Where in the world is alpha gal?”

Mayo Clinic: “Anaphylaxis, Symptoms & causes, Overview.”

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