Can a Tick Bite Trigger a Meat Allergy — and Raise Heart Disease Risk?

A tick bite is best known for spreading Lyme disease, but it can also trigger a potentially life-threatening meat allergy called alpha-gal syndrome (AGS) — and researchers are now investigating whether the immune response behind it may also raise the risk of heart disease. The Centers for Disease Control and Prevention estimates that up to 450,000 people in the U.S. may currently be affected by AGS. "The range is moving farther north and west, and more states are being affected," said Dr. Sachin Shah, a professor of pharmacy practice at the University of the Pacific in Stockton, California.

Alpha-gal is a sugar molecule naturally found linked to proteins and fats in most mammals — including in beef and pork — but not in humans or other primates. The molecule itself is not harmful to eat. A bite from certain ticks, usually the lone star tick, can trigger an immune response in which the body develops antibodies against alpha-gal; future exposure to alpha-gal in food can then cause a delayed allergic reaction. Not everyone bitten develops the syndrome, and it is not yet known why some people do and others don't.

Researchers are increasingly interested in whether the immune response behind AGS could affect cardiovascular health. "There is a growing body of evidence linking allergic diseases and inflammation with heart disease," said Dr. Jeffrey Wilson, an allergist and immunologist at the University of Virginia School of Medicine. Antibodies produced in response to allergens may help drive inflammation throughout the body, and researchers suspect chronic inflammation may play a role in coronary artery disease, in which plaque builds up in the arteries supplying blood to the heart. A 2018 study led by Wilson was the first to find a connection between alpha-gal antibodies and heart disease, and a larger 2022 study linked alpha-gal sensitivity to higher levels of artery plaque and a greater risk of serious heart attacks.

Wilson and other experts caution that more research is needed on a possible link between alpha-gal antibodies and coronary artery disease. Alpha-gal syndrome is diagnosed using a combination of symptom history and a blood test for alpha-gal antibodies, since many people who carry the antibodies never develop symptoms. Reactions to alpha-gal typically appear three to five hours after eating, a delay that makes the allergy unlike most others, which usually cause symptoms soon after ingestion.