One bite from a lone star tick could cause an allergy to red meat for life
Recent warm weather has reawakened ticks, and one type, in particular, is becoming more common in the D.C. area: the lone star tick. One bite from this tick, which is easily identified by the white spot on its back if it’s a female, can cause a life-long adverse reaction to eating red meat.
The lone star tick originated in the southern states but has spread north and west to cover much of the eastern half of the country. 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 known as alpha-gal syndrome,whichis 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.
Because people don’t have alpha-gal in their bodies, 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 bite site becomes swollen and itchy.
But red meat, which contains alpha-gal sugars, can further trigger reactions. If red meat is eaten by people bitten by the lone star tick, the immune system recognizes the alpha-gal from the meat as a foreign substance. As a result, the body mounts a 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. In 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 meat is ingested. In addition, the allergy to red meat lasts a lifetime and can become worse over time.
Living with alpha-gal syndrome
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: “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 and broke out in a rash over most of his body. A week later, another hamburger caused the same rash. Later, a third hamburger led to 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. The diagnosis was indeed alpha-gal syndrome. “It was not comforting when I realized I knew more about alpha-gal than a medical professional,” he said 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.?”
Since 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, a retired entomologist from the Maryland Department of Agriculture, was bitten awhile 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. He 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 he reacted poorlyto lamb. Finally, he found an allergist who correctly diagnosed his condition as alpha-gal syndrome.
Gimpel remains optimistic despite his 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 last month in the D.C. area but have not developed the allergy to red meat … yet. In fact, I have been bitten by more than a dozen lone star ticks.
The increase in ticks can be attributed to warmer temperatures across the seasons. Michael Raupp, entomology professor emeritus 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, which increases their chances of survival. In addition, Raupp said, a boost in animals on which the ticks feed, such as white-tailed deer, also helps increase the tick population.
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, and ehrlichiosis, which produces flu-like symptoms, including headache, joint and muscle aches, 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 from the dog tick and is much larger than the deer tick (see photo above).
If you do contract alpha-gal syndrome, though, genetically modified meat may be an option. 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, Revivicor, has been mailing packages of its alpha-gal-free pork to people with the syndrome. The meat appears not to produce an allergic reaction.
In December 2020, the Food and Drug Administration 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 the syndrome.
Perhaps one day, Tremel can barbecue pork ribs for competition and do his own taste test. And then eat the leftovers.
Tick makes its way to Mexico
Earlier this year, researchers in northwest Mexico reported that as many as one in five children who got the disease died from it.
model (Fig 2A) identified areas with different levels of suitability for lone star ticks across North America. Highly suitable areas were concentrated in the lower Midwest and South, and suitability declined towards the central United States and southeastern Canada. Broad areas in northern California and the west coast of Oregon, Washington and British Columbia were suitable as were disparate areas in Mexico, with suitable areas extending into northern Central America. Much of the Caribbean was also identified by this model as highly suitable, although it may not be accessible to the species. The present-day model showed low uncertainty throughout the predicted distributional area (Fig 2B), and the MOP analysis revealed that only the southwestern United States and northern Mexico would present model extrapolation in current conditions (Fig 2C).
Fig 2Climatologically suitable regions for Amblyomma americanum distribution in North America.
a. Median prediction. b. Uncertainty associated with the median prediction of suitable regions for Amblyomma americanum in North America. c. Mobility-oriented parity analysis revealing areas in N. America for which the present-day model predictions are strictly based on extrapolation.
The models identified a future potential distribution that reflected dramatic expansion of the distributional potential of lone star ticks from the present distribution. Composite maps (i.e., across the four GCMs) for RCP 4.5 (Fig 3A and 3B) and RCP 8.5 (Fig 4A and 4B) both indicated potential range expansion well into the upper Midwest, southeastern Canada, and contiguous areas of the western United States. Predictions from different GCMs differed, as can be appreciated from the different levels of agreement in Figs Figs3A3A and and4A.4A. A predicted potential range retraction in Mexico is rather less certain, as our occurrence data were exclusively from the United States and Canada and did not represent the Mexican part of the species’ range. The MOP analysis of future climates for both scenarios indicated that model predictions for broad areas in southern California, Mexico, and Central America were based on extrapolative conditions (Figs (Figs3B3B and and4B4B).
Fig 3Predicted future suitable regions under climate change scenarios.
a. Predictions under the Representative Concentration Pathway (RCP) 4.5, and agreement between different Global Circulation Models. 1 = areas in which one of the four GCMs predicted suitability for Amblyomma americanum distribution. 2, 3, 4 = two, three and four GCMs predicted suitability, respectively. 5 = areas in which one of the four GCMs predicted loss of territory for A. americanum compared to the present-day distribution. 6, 7, 8 = two, three, and four GCMs predicted loss of territory, respectively. b. Agreement among Global Circulation Models (GCMs) in North America with strict extrapolative conditions under the low emissions, RCP 4.5 scenario. 1 = Areas in which the prediction based on one of the four Global Circulation Models (GCMs) were strictly extrapolative. 2, 3, 4 = degree of agreement in strict extrapolative areas based on two, three and all four models, respectively.
Fig 4Predicted suitable distribution under climate change scenarios.
a. a. Predictions under the Representative Concentration Pathway (RCP) 8.5 and agreement between different Global Circulation Models (GCMs). 1 = areas in which one of the four GCMs predicted suitability for Amblyomma americanum distribution. 2, 3, 4 = two, three and four GCMs predicted suitability, respectively. 5 = areas in which one of the four GCMs predicted loss of territory for A. americanum compared to the present-day distribution. 6, 7, 8 = two, three, and four GCMs predicted loss of territory, respectively. b. Agreement among Global Circulation Models (GCMs) in North America with strict extrapolative conditions under the high emissions, RCP 8.5 scenario. 1 = Areas in which the prediction based on one of the four Global Circulation Models (GCMs) were strictly extrapolative. 2, 3, 4 = degree of agreement in strict extrapolative areas based on two, three and all four models, respectively.