The tick that makes people allergic to red meat spreads north and west in U.S.

Lone star tick

Spring weather has reawakened ticks, and one tick, in particular, is becoming more common in the eastern U.S.: the lone star tick. One bite from this tick, which is easily identified by the white spot on its back if it’s female, can make people have adverse reactions to eating red meat for life.

The lone star tick originated in the Southern states but has spread north and west to cover much of the eastern half of the U.S. With a warming climate, more ticks survive the winter months, and their range is expanding.

Unlike the black-legged (deer) tick, the lone star tick doesn’t transmit Lyme disease, but it can produce a severe food allergy in people called alpha-gal syndrome, which is an allergy to red meat.

When lone star ticks feed on mammals, such as mice, rabbits, or deer, they ingest alpha-gal sugars. Later, if the ticks bite and feed on humans, they inject the alpha-gal sugars with their saliva into their human host.

Primates don’t have alpha-gal in their bodies. Therefore, the human immune system recognizes alpha-gal from a tick bite as a foreign substance and mounts a response, including the development of antibodies. Often, the tick bite site becomes swollen and itchy.

However, after the lone star tick bite, if red meat is eaten, which also contains alpha-gal sugars, the immune system recognizes the alpha-gal from the meat as a foreign substance. As a result, it mounts another response, often much more severe than the initial response to the tick bite.

The alpha-gal allergy to red meat can lead to a rash, hives, itching, swelling, shortness of breath, headaches, abdominal pain, diarrhea, and vomiting. With severe cases, a person may suffer anaphylaxis, a potentially fatal allergic reaction.


Initially, alpha-gal syndrome was hard to diagnose because the allergic reaction occurs many hours after eating meat. In addition, the allergy to red meat lasts a lifetime and can become worse with time.

Keith Tremel from Edgewater, Md., is a competitive barbecue cook who can’t eat or taste his smoked beef and pork dishes. He needs to wear rubber gloves when handling red meat, or he’ll break out in a rash. He contracted alpha-gal syndrome after a lone star tick bite five years ago and is highly allergic to most of the meat he cooks.

Tremel remembers the tick bite that gave him alpha-gal syndrome: “I was bitten on the thigh by a tick while I was sleeping. It woke me up. I pulled the tick off and immediately saw the white dot. I had recently read an article about alpha-gal and lone star ticks, so I instantly recognized it. I wouldn’t say the bite was painful, but it did wake me up.”

Soon after the tick bite, Tremel ate a hamburger which produced a rash over most of his body. A week later, another hamburger made the same rash. Later, a third hamburger had a similar outcome, and Tremel went to see a doctor, fearing alpha-gal syndrome.

Tremel’s doctor had never heard of alpha-gal and looked it up on his laptop while Tremel waited. Later, the diagnosis was alpha-gal syndrome. “It was not comforting when I realized I knew more about alpha-gal than a medical professional,” said Tremel in an email.

“Before my diagnosis, I loved bacon cheeseburgers. My wife and two kids both like bacon, and my son enjoys steak, so cooking that for them can be a little bit of torture. As for barbecue competitions and catering, I’m used to it now, but in the beginning, it was frustrating.”

Tremel and his teammates compete in the Kansas City Barbeque Society, cooking chicken, ribs, pork and brisket at each contest. Chicken, he said, is the only meat he can sample. For the rest of the dishes, he relies on his “teammates’ taste buds to make any last-minute changes to our turn-ins, like does it need more spice, less spice, is it salty, too sweet, etc.?”

After Tremel’s alpha-gal diagnosis, his favorite foods have changed to chicken tacos and pizza. “So far, dairy has not affected me, so cheese is still okay.”

William Gimpel, retired entomologist from the Maryland Department of Agriculture, was bitten by a while ago by a tick in the Northern Neck of Virginia. But he wasn’t officially diagnosed with alpha-gal syndrome until six years ago.

Gimpel’s allergic reaction to red meat was severe. Gimpel said in an email, “I developed hives, fainted, my blood pressure dropped, and I told my wife on the way to the ER that I could not see. That has been my most serious reaction.”

Initially, Gimpel was told he was allergic to beef. So, he dined on pork, lamb, and venison for several years. Then he had an allergic reaction to pork, and three months later reacted poorly to lamb. Finally, he found an allergist who correctly diagnosed his condition as alpha-gal syndrome.

Gimpel remains optimistic about his alpha-gal allergy. He wrote, “The best news is I eat all of the non-red meats, including chicken, turkey, fish, crabs, and other shellfish!”

Not all lone star tick bites produce alpha-gal syndrome. I was bitten by one earlier this month in the D.C. area, but have not developed the allergy to red meat … yet. In fact, I have been bitten by over a dozen lone star ticks.

The increase in ticks can be attributed to warmer temperatures across the seasons. Michael Raupp, entomology professor at the University of Maryland, said warmer temperatures in the winter allow more ticks to survive the usually harsh season. Mild weather in the fall, winter and spring also allows them to actively seek hosts for longer periods of time, which increases their chances of survival. Lastly, Raupp said a boost in animals the ticks feed on, such as white-tailed deer, also help boost tick populations.

In addition to alpha-gal, the lone star ticks transmit diseases, including Southern Tick Associated Rash Illness (STARI), which produces a rash, fever, fatigue, and pain in muscles and joints. Another disease spread by the lone star tick is ehrlichiosis, which has flu-like symptoms including headache, joint and muscle ache, fever, and fatigue.

The female lone star tick has a white spot on its back, but the male does not, making it harder to identify. However, the lone star tick has a different shape than the dog tick and is much larger than the deer tick.

If you do contract alpha-gal syndrome though, some are opting for genetically modified meat. Recently, pigs have been genetically modified to remove alpha-gal sugars so their organs can be transplanted in humans with a lower chance of rejection. The leftover meat can be used as food for people with alpha-gal syndrome.


One company named Revivicor has been mailing packages of their alpha-gal-free pork to people with alpha-gal syndrome. And so far, it appears the meat from the alpha-gal-free pigs can be eaten without an allergic reaction.

In December 2020, the FDA approved the genomic alteration of pigs for human food and cosmetics, so there may be a future for selling alpha-gal-free meat to people with alpha-gal syndrome.

Perhaps one day, Tremel can barbecue pork ribs for competition and give it a taste test himself, without help from others. And then eat the leftovers.