Mandy Litteral's daughter was setting up a show-rabbit stall at a Kentucky county fairground when a tick bit her. Months later, in November 2017, the 8-year-old woke up with swollen lips and tongue and a constricted throat — anaphylaxis. The last thing she had eaten was Gatorade and ibuprofen for a headache. It would take three more years, a false diagnosis of gluten sensitivity, and daily anaphylactic episodes before doctors identified what was actually happening to Harmony Litteral: alpha-gal syndrome, a red-meat allergy triggered by a tick bite that a growing body of research says is both more common and more medically serious than most consumer coverage acknowledges. [1]
"People are not educated enough about alpha-gal," Mandy Litteral said. "Alpha-gal affects people in different ways. It's not like any other allergy." [1] Her daughter's early doctors had never heard of the condition. One suspected gluten intolerance and sent the family looking in the wrong direction — Harmony avoided bread but kept eating bacon and burgers, not realizing the mammal meat itself was the trigger, and continued having reactions hours later. By the time she reached specialists in 2021, she was in anaphylaxis "every single day," her mother said, with gastrointestinal problems, kidney stones, and a throat that closed at the mere smell of meat cooking. [1]
Alpha-gal syndrome, or AGS, develops when a tick injects a sugar molecule called galactose-alpha-1,3-galactose into the bloodstream, and a susceptible person's immune system forms antibodies against it. Because that sugar is present in the meat and byproducts of nearly all mammals — beef, pork, venison, dairy — the resulting allergy can turn ordinary meals into medical emergencies. In the United States, the lone star tick is the most common culprit; the species is expanding out of its traditional Southern range into the Midwest and Northeast, and black-legged ticks, the same species that spreads Lyme disease, have also been linked to cases. [1]
Experts estimate roughly 500,000 people in the US now have AGS, up from a 2023 federal estimate of 450,000. "Based on more recent data and the trends that we're seeing, we probably imagine that there have been an additional 50,000 cases," said Scott Commins, an allergist and immunologist at the University of North Carolina at Chapel Hill who treated Harmony. [1] A separate study of five tick-heavy states found that one in four adults tested positive for alpha-gal antibodies — though antibodies alone don't confirm a diagnosis, since many people carry the antibody without ever developing symptoms, a pattern also seen with peanut and other food allergies, according to University of Virginia allergist Jeffrey Wilson. [1] The condition was first described in US medical literature only in 2007, making it, in Commins' words, "a young diagnosis" that researchers are still working to fully characterize.
Severity varies widely. Some patients can still tolerate dairy; others must avoid every trace of mammal product, including skin care items, gelatin capsules and certain medications. Bobbi Pritt, who chairs clinical microbiology at the Mayo Clinic, said doctors first recognized the syndrome's danger through patients who had severe, sometimes immediate anaphylactic reactions to cetuximab, a cancer drug derived from mammal cells. [1] Reactions to food classically arrive hours after eating — often overnight, since red meat is commonly an evening meal in the US — which can make the connection to a meal eaten hours earlier hard for patients and even doctors to trace. [1]
This week, researchers added a complication almost no consumer coverage of alpha-gal has mentioned: the allergy can make blood transfusions dangerous. A study published in JAMA Internal Medicine found that alpha-gal syndrome patients with blood type O face significantly higher risk of severe allergic reactions when transfused with platelets or plasma from donors with type B or AB blood — because the alpha-gal sugar molecule closely resembles the B blood-group antigen, allowing alpha-gal antibodies to mistakenly attack transfused blood products. [2]
A team led by Dartmouth Hitchcock Medical Center analyzed nearly 559,000 platelet and plasma transfusions across 40 sites in five countries. In nine US sites located in regions with high AGS prevalence, type O patients who received B or AB blood products had nearly four times the rate of allergic transfusion reactions compared with type O patients who received type O products — a risk ratio of 3.93. No such excess appeared among type B patients, and sites in low-AGS-prevalence regions and outside the US showed no clear signal at all. [2] "We anticipate that this will change transfusion practices in the U.S., at least in AGS high-prevalence regions," said lead author Richard Kaufman, a Dartmouth pathology professor. Dartmouth Hitchcock has already stopped giving B or AB platelets to type O patients. [2]
Harvard Medical School physicians reviewing the study called it "the strongest data to date" supporting what researchers are calling transfusion-related alpha-gal syndrome, even while cautioning that documented cases remain "vanishingly small" for now — a caveat that argues for awareness, not alarm. Study coauthor Nancy Dunbar, a Dartmouth Hitchcock pathologist, tied the finding to a broader pattern: "The changing climate and ensuing greater proliferation of ticks is leading to illnesses and symptoms we had not seen before, and we continue to learn about them in real time." [2]
For Harmony Litteral, now working toward the remission Commins told her was possible if she avoided mammal products through age 18, the transfusion study is a reminder of how much about her own condition remains unmapped. For hospitals in tick country, it is a concrete, actionable warning — one that a syndrome still routinely described as a food-allergy curiosity is only now generating the clinical evidence to support.
-- NORA WHITFIELD, Chicago