Mysterious new allergy is triggered by a tick bite.
[Updated July 27, 2017]
It’s an allergy ripped from the pages of a science fiction novel. A lone star tick, widespread in the southeast, mid-Atlantic and northeast regions of the United States, bites an unsuspecting subject. Four to eight weeks later, the victim starts to notice some odd reactions. There may be itching on the palms of the hands and soles of the feet. There usually is a very bad night, where the person is awakened around midnight due to an outbreak of hives. There may be diarrhea, nausea, vomiting. Some people feel dizzy, their blood pressure drops, their throat begins closing up and they start going into anaphylactic shock.
The tick bite, as it turns out, has triggered an allergic reaction to meat, specifically to beef, pork, lamb and venison—but not to chicken, turkey or fish.
Meat allergy from a tick bite? As bizarre as it sounds, it is a real medical condition that is becoming more common in the United States.
Scientists at the University of Virginia are at the forefront of trying to understand what makes the allergy tick, as it were. They say that tick saliva may trigger some people to produce allergic IgE antibodies to a sugar (a simple carbohydrate) in meat, called galactose-alpha-1,3-galactose—or alpha-gal, for short. When people with the allergic alpha-gal antibody eat meat from mammals, an allergic response kicks in that, in the worst case, can lead to anaphylaxis.
This allergy is even more confounding because up until now, food allergies have always been associated with reaction to proteins—but alpha-gal is a sugar. Plus, food allergy reactions are usually immediate (within minutes to an hour), whereas a person with the alpha-gal allergy doesn’t react for four to six hours.
Tick as Trigger
In 2012, Elizabeth Wenig was diagnosed with the alpha-gal allergy. When Wenig, who owns Rocky Creek Valley Farm in Rayville, Missouri, with her husband, tells others about her meat allergy, they are astounded.
“Their mouths fly open. Some people laugh outright. It’s just the most absurd thing,” Wenig says. “I can tell that some people don’t believe me when I’m saying it. They think it’s ridiculous: ‘You can’t be allergic to meat!’ I remember having a similar reaction when I first heard about it.”
Wenig raises a herd of dairy goats on her farm. Every morning, she takes the goats out to the “mountain,” a huge, wooded hill behind the barn.
“It was a regular occurrence for me to be bitten by ticks. I never thought anything about it,” she says.
Wenig does not recall getting an unusually angry tick bite, something that many people with alpha-gal allergy report experiencing. But hours after dining on roast beef one evening, she had a reaction.
“I had itching on my hands and feet. It started around midnight,” she explains. “The next day, the itching kept getting worse. I was driving to town and the palms of my hands were so itchy and on fire, I remember rubbing them back and forth on the steering wheel. After I got home, I looked under my clothes and there were huge, swollen, red welts and hives all over my body.”
Wenig has a history of anaphylaxis due to other allergies, mostly to medication. Now her symptoms were beginning to feel frighteningly familiar.
“When I start to go into anaphylactic shock, it’s like a light on a dimmer. It gets dimmer and dimmer and you feel yourself going down. You know you’re going to pass out,” she says.
By that evening, she called her daughter-in-law, who came over and rushed her to the emergency room. She ended up being in the hospital for three days.
“They told me it was an allergic reaction but they didn’t know what had triggered it. I was just terrified because whatever it was, I didn’t want it to happen again,” she says.
A few days later, her daughter-in-law’s mother heard a news report about a tick-borne meat allergy. Wenig asked her family doctor to order a blood test for alpha-gal but he refused. She went to three other physicians before she found a doctor who would order the blood test. In a few days, test results came back positive for the alpha-gal allergy.
“I was at once joyful and sad,” Wenig says. “We discovered what had caused the reaction but it meant I’d have to give up meat. I’m a big meat eater. I love meat and I love milk.”
Alpha-gal is also present in dairy products. While most individuals with alpha-gal allergy do not react to dairy, some do. Wenig found that when she ate dairy, her toes and the balls of her feet would swell up, becoming itchy and painful.
“That broke my heart,” she says. “Not only am I a milk lover, I have dairy goats so I used to drink a lot of goat’s milk. For me, the allergy goes much farther than just avoiding meat and milk. If there’s something that might have some kind of a mammal ingredient in it, then I try to avoid it. There are hundreds of products I can’t have. We’ve pretty much eliminated eating out because if the restaurant is using any packaged food, I might be in trouble.”
Unraveling the Mystery
In 2007, Thomas Platts-Mills, MD, PhD, a University of Virginia professor of medicine in allergy and clinical immunology, was investigating unusual reactions to a cancer medication. In certain areas of the United States — North Carolina, Arkansas, Missouri, Virginia and Tennessee— patients were showing a baffling hypersensitivity to the drug cetuximab.
“The reactions were troubling,” says Scott Commins, MD, PhD, an allergist and immunologist at the University of Virginia, who began working with Platts-Mills in 2008. “It just didn’t add up. The more people we screened, the more we came across these strange positives.”
Platts-Mills and his colleagues were able to determine that the antibodies were to a sugar, galactose-alpha-1,3-galactose—or alpha-gal, for short. (Alpha-gal is present in nonprimate mammals but not in humans.)At the same time, patients in general allergy clinic were telling Platts-Mills and Commins, “I know it sounds really weird but I swear I’m allergic to beef.” Yet these same patients would have a negative skin test for a beef allergy.
The researchers finally hit pay dirt when they looked at a map that charted the occurrence of Rocky Mountain spotted fever, a tick-borne infection.
“We thought, wow, that not only looks like the distribution of these cancer cases with increased incidence of hypersensitivity to cetuximab but it also really correlates with patients who have this red meat allergy. So we thought, let’s start asking our patients about tick bites,” Commins says. “It opened up a Pandora’s box.”
“Hearing the stories in the clinic and having this lab research going on, we couldn’t have designed it to coincide any better,” Commins says. “It was really a strange set of circumstances. I don’t know if we could ever repeat it.”
All three life stages—larva, nymph and adult—of the aggressive lone star tick feed on humans. The nymphs are often called seed ticks, because they are the size of poppy seeds; sometimes they’re mistaken for chiggers.
“I now ask patients if they’ve been bitten by ticks, seed ticks or chiggers,” Commins says. “If you ask it that way, it’s amazing— 95 percent of patients who end up with the allergy answer yes to that question.”
“It’s clear to us that lone star ticks can cause the allergy. But it’s not at all clear that this is the only way it happens,” Commins explains, noting that the alpha-gal allergy has also been reported in parts of Australia, Europe and Japan. “The global data would argue that it really is not specific to lone stars, that other ticks can trigger it, too.”
“There’s a group of patients who develop a really brisk reaction to a tick bite but by no means does everyone who has been bitten develop the allergy,” he says. The quantity of tick bites, as well as the quantity and type of meat eaten, might figure into the allergy, as well.
As a general rule, patients are told to avoid all meat from mammals. Some patients cannot tolerate any dairy, while others can tolerate milk in their cereal but have allergic reactions to ice cream or to creamy cheeses, like brie. Some can eat very lean cuts of venison without symptoms.
Fat plays a key role. That’s because alpha-gal is a sugar that attaches to fat molecules, existing as a glycolipid. The way fats are absorbed in the body may explain the four-hour delay in developing a reaction.
“If you look at how fat is absorbed in the body, it takes about four hours for lipids to make it to the bloodstream after a meal,” Commins says. “Not only could this explain the delay but it also explains a lot of what we see in clinic with patients telling us, ‘If I eat a really lean piece of meat, I don’t always have problems but if I eat ten pieces of bacon, I’m totally going to have a reaction.’”
The allergy may not last a lifetime. Alpha-gal antibody levels can eventually drop in patients who avoid additional tick bites. In time, some people get a negative blood test for the antibody and pass a food challenge, enabling them to eat meat again.
“This does not seem to be a forever allergy. It appears the antibody level goes down after a period of time,” Commins says. “However, I would caution patients: Be aware that if you get more tick bites, especially the ones that become red, itchy, inflamed and tend to stay for a while, you may well develop this whole thing all over again.”
Serves 4 to 8.
This easy gluten-free recipe was developed specifically for those with the alpha-gal allergy. Use it to replace ground beef or pork. It makes a delicious breakfast sausage and an excellent substitute for beef in chili, gluten-free spaghetti and tacos. For variety, add diced peppers and onions or a little maple syrup.
1 pound ground turkey
1 clove garlic, minced
2 heaping teaspoons ground sage
¾ teaspoon red pepper flakes
½ teaspoon celery salt
½ teaspoon ground cumin
½ teaspoon salt
½ teaspoon fresh ground pepper
1. Place all ingredients in a bowl and knead until mixed well.
2. Form mixture into 6 or 8 balls and press them into thin patties or crumble for a ground beef substitute.
3. Cook in a skillet over medium heat for 5 minutes or until no longer pink.
Each serving contains 86 calories, 5g total fat, 1g saturated fat, 0g trans fat, 45mg cholesterol, 205mg sodium, 0g carbohydrate, 0g fiber, 0g sugars, 10g protein, 0 Est GL.
TIP For a quick breakfast, make several batches in advance. Form into patties and place on a cookie sheet. Freeze and then transfer to a plastic freezer bag. The night before serving, remove the patties you need and defrost in the refrigerator overnight.
Recipe adapted from rockycreekvalley.com. Used with permission.
While the researchers have made great strides, there are still many unknowns. Could other types of ticks also be responsible? How long must a tick be attached to trigger the allergy? Are these ticks carrying a bacteria? Is a substance in the tick’s saliva to blame? Why do some people develop the allergy but not others? Why do some people develop hives and others have gastrointestinal symptoms, like abdominal cramping, diarrhea, nausea or vomiting?
Tina Moore, who lives in Millsboro, Delaware, had allergic reactions to meat for eight years before her alpha-gal allergy was diagnosed in November 2011.
A technician for Verizon, Moore works out in the field, climbing poles, installing and repairing telephone services. Tick bites are a common occurrence, even with long pants tucked into her high-top boots. But there’s one particular bite she remembers. Swollen and red, it took forever to heal.
A few months later, Moore broke out in hives. Her hives became bigger, growing together to the point where her entire body looked like one huge hive. When her mouth, tongue and lips ballooned and she began going into anaphylactic shock, she was rushed to the emergency room. She had hives almost daily after she was discharged and had to take steroids for six months. Working with an allergist and keeping a food diary, she finally figured out that beef was to blame. So she switched to pork but she reacted to pork. She reacted to lamb. She reacted to venison.
One day, she was looking for answers online at an allergy message board. Somebody wrote, “I bet you got a tick bite.”
“I typed back, ‘Don’t be absurd. Everyone knows that ticks don’t cause food allergies,’” Moore recalls. “I was amazed and I was absolutely livid that this allergy had been around and my doctor had never suggested it to me.”
About a year ago, Moore launched an alpha-gal Facebook group for people to share tips and experiences about the allergy.
“I started it because I was angry and I thought there had to be people in the same boat that I am,” Moore says. “I thought I should reach out and help those people. And I wanted answers.”
Members discuss their symptoms, the latest alpha-gal research and recipes. They also share tidbits about foods and medications that contain hidden meat — Buffalo Wild Wings are cooked in beef fat; Cracker Barrel corn muffins are cooked with bacon grease; some turkey sausages are made with beef casing; marshmallows and gummy candies usually contain animal gelatin; medicine gel caps can contain gelatin.
“Some members are frustrated because their doctors don’t believe this is real. I’ve learned more from these people and have been helped out more by this group than by my doctor,” she says. “Everyone is so different and their reactions are so different — they share that in the group. I didn’t want to be alone with this. Now I’m not alone.”
Adults and Children Alike
While the alpha-gal allergy has been reported in more than 2,000 adults, it’s been reported in only about 45 children. (Compare this figure to the roughly 25,000 new cases of Lyme disease reported every year.) In a study published in the journal Pediatrics in May, Commins states that kids can have severe reactions to alpha-gal. Almost half of the children in the study had to go to the emergency room for treatment.
Andrea Roseman’s 9-year-old son Grant has the alpha-gal allergy. Before being diagnosed, he had sporadic outbreaks of hives. But during his last outbreak, he didn’t just have hives—his throat began closing up.
As anyone with a food allergy knows, avoiding hidden ingredients and cross-contamination isn’t easy. Grant carries an EpiPen everywhere he goes in case of accidental exposure. The whole family has switched from a meat-lover’s diet to one that relies on ground turkey, chicken and fish.
Roseman, who lives in Cape Girardeau, Missouri, was already homeschooling Grant and his younger sister. With his diagnosis, she’s intent on continuing to do so. “If I had to send him to school and trust other people every day, all day, I think I would be a wreck,” she says. “It would be a lot worse if he were younger and couldn’t tell people, ‘I can’t eat that.’ If someone offers him candy or something suspect, he knows how to check out the ingredients. He knows what to look for.”
Grant is in a unique position. The family does not personally know any other children with alpha-gal. Still, when Grant participates in 4-H, Cub Scouts and social get-togethers, Roseman is amazed at how supportive their community is.
“Everyone’s been really great about it. Our family, they always make sure that what they’ve bought is food he can eat. We’ve been really blessed in this way.”
Looking back, Roseman thinks she knows when Grant was exposed.
“We camp. We’re out in the woods a lot,” she says. “There was one time we thought he had chigger bites. Apparently when seed ticks bite, they look like chigger bites. He had them all over his ankles and feet. We’re pretty sure that’s when he contracted the allergy.”
Getting the Word Out
Allergists are becoming increasingly aware of the alpha-gal allergy but it remains relatively unknown among general practitioners. When internist Susan Wolver, MD, learned about alpha-gal from a patient, she was initially doubtful.
“It’s paradigm shifting to have anaphylactic shock to anything that is delayed,” says Wolver, an assistant professor of general internal medicine at Virginia Commonwealth University Health System. “The essence of anaphylactic shock is you eat something or you get an injection or you get stung by a bee and within 30 to 60 minutes, you have a reaction. It’s not standard to have a four-hour to six-hour delay before developing anaphylaxis. When I talked to my colleagues about it, they were aghast. They couldn’t believe it.”
To help alert general practitioners to the allergy, she wrote an article in the Journal of General Internal Medicine, published in February.
“It’s important for primary care doctors to know that this allergy exists. They need to consider it when they see a patient who has unexplained hives or anaphylaxis, especially those who wake up in the middle of the night after having meat for dinner,” she says.
The blood test for IgE antibody to galactose-alpha-1,3-galactose (conducted through Viracor-IBT Laboratories), must be ordered by a physician and blood must be drawn in a doctor’s office. Standard allergy skin tests are not accurate for diagnosing alpha-gal.
Elizabeth Wenig’s husband created a page on their Rocky Creek Valley Farm website devoted to alpha-gal information and recipes. A certified clinical herbalist, Wenig gives informative presentations on herbs, organic gardening and natural animal husbandry. She also talks about the alpha-gal allergy.
“It’s been a wild ride. I’m trying to educate the people in my area because when the symptoms hit, you’re so in the dark about what’s causing them,” she says.
Tina Moore has become used to not eating beef. “You learn to improvise. You learn to try other things. You learn to expand your palate. If a recipe calls for ground meat, I just use ground turkey or ground chicken instead. My new steak is seared tuna,” she says.
The health implications of being forced to give up meat aren’t lost on Moore, who has a family history of heart disease.
“My dad died from a heart attack at age 55,” she says. “I consider this allergy a godsend.”
Chicago-based health writer Eve Becker is author of glutenfreenosh.com. Her daughter has celiac disease.