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A single tick bite could trigger a lifelong allergy to red meat in some, and new federal data suggest the condition is far more common than doctors previously thought, especially in five specific U.S. states.
Nearly one in four adults in the states hit hardest by the lone star tick carry antibodies linked to alpha-gal syndrome, a potentially life-threatening allergy to red meat, according to a study published in the Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report.
Dr. Chirag Patel, chief of Allergy and Immunology at Hackensack Meridian Jersey Shore University Medical Center, told Newsweek that alpha-gal syndrome behaves unlike most food allergies.
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"What makes this allergy unique is that reactions are typically delayed, occurring three to six hours after consuming mammalian meat, and reactions may not occur every time, which can make diagnosis challenging," Patel said.
He said the condition is often mistaken for a stomach bug rather than an allergy.
"Many patients experience gastrointestinal symptoms such as abdominal pain, nausea, vomiting, and diarrhea—sometimes without the hives or skin rashes commonly associated with allergic reactions," he said. "In severe cases, life-threatening anaphylaxis can occur."
How a Tick Bite Causes a Meat Allergy
Alpha-gal syndrome develops when a tick bite prompts the immune system to react to galactose-alpha-1,3-galactose, or alpha-gal, a sugar molecule found in beef, pork and lamb. In the U.S., the lone star tick is the species most often blamed.
Patel said repeated bites can make the allergy worse.
"Recurrent tick bites may worsen or perpetuate the allergy over time, making tick avoidance an essential part of management," he said.
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For the study, researchers tested roughly 3,000 blood samples collected between November 2024 and April 2025 from residents of 10 states. The share of people carrying alpha-gal antibodies tracked closely with where lone star ticks are established.
Arkansas had the highest rate, at 31 percent of residents. Missouri followed at 26 percent. Across the five hardest-hit states—Arkansas, Kentucky, Missouri, Tennessee and Virginia—about 24 percent of residents tested positive for the antibodies.
Patel pointed to those same figures as evidence of how widespread exposure may be.
"While not everyone who is sensitized will develop clinical symptoms, these numbers suggest that alpha-gal syndrome may be far more widespread than previously recognized," he said.
Researchers cautioned that carrying antibodies does not mean someone has, or will develop, full-blown alpha-gal syndrome.
They warned that blood tests alone could lead doctors to "overdiagnose" the condition, since many people test positive without ever having an allergic reaction. Alpha-gal syndrome was estimated to affect up to 450,000 Americans in 2022, but researchers say that figure likely undercounts how many people have been exposed.
Patel said the safest path for diagnosed patients is avoiding mammalian meat entirely, while poultry, fish and shellfish remain safe options. Some patients can tolerate small amounts of dairy, he said, but that should be watched closely.
He also warned that hidden animal ingredients—including beef broth, lard and pork casings—can trigger reactions, so patients need to read food labels carefully. Patel said anyone diagnosed with the condition should speak with their physician about carrying an epinephrine auto-injector and know how to use it.
Reference:
Saunders EF, et al. Alpha-gal Immunoglobulin E Seroprevalence Among Blood Donors — 10 States, 2024–2025. Morbidity and Mortality Weekly Report (2026). DOI: dx.doi.org/10.15585/mmwr.mm7525a1
Contact Newsweek editors on this story: Kara Dolman and Emma Lee-Sang
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