The Lone Star Tick May Make You Allergic to Red Meat - AARP

When temperatures warm and foliage blooms, doctors and public health experts urge people to take proper tick precautions before heading outdoors. A bite from one of the little bugs could result in a disease, like Lyme or babesiosis. It could also lead to a strange but serious food allergy that, for meat-eaters, could sideline summer barbecue plans.

Alpha-gal syndrome is an allergy to red meat that can be triggered weeks after a bite from the lone star tick and possibly other varieties. And like tick-borne diseases, which are on the rise in the U.S., so are cases of alpha-gal.

"We're continuing to identify new patients every week in allergy clinics across the Southeast and East who've had essentially brand-new reactions," says Scott Commins, M.D., an associate professor of medicine at the University of North Carolina and a leading expert on alpha-gal syndrome. "And that has been a big change over the past, say, 10 years."

More than 34,000 people in the U.S. have tested positive for alpha-gal syndrome, according to research published by Commins and his colleagues in 2021.

What is alpha-gal?

Alpha-gal is a sugar molecule — many mammals have it, including cows and pigs, and Commins says researchers have come to understand that some ticks do too. But it's not found in people, so when a person gets a bite from a tick that has alpha-gal in its saliva, the body creates an immune response to the molecule, and some people create a strong allergic response.

Symptoms of alpha-gal syndrome

Reactions can range from mild to severe and may include:

• Hives or itchy rash

• Nausea or vomiting

• Heartburn or indigestion

• Diarrhea

• Cough, shortness of breath or difficulty breathing

• Drop in blood pressure

• Swelling of the lips, throat, tongue or eyelids

• Dizziness or faintness

• Severe stomach pain

Source: Centers for Disease Control and Prevention 

"So then when we eat a hamburger, hotdog, etc., we have an allergic reaction to the meat, and it's specifically to that alpha-gal that's in pigs and cows," Commins says. This is the case even if a person has been able to eat red meat their whole lives without issue. 

Recognizing the symptoms of alpha-gal

Unlike other food allergies, symptoms of alpha-gal syndrome don't come on right away. "If you have a peanut allergy and you go out to a restaurant and you get an accidental exposure, you know you're in trouble before you leave the restaurant," says Jeffrey Wilson, M.D., an allergist and immunologist and assistant professor of medicine at the University of Virginia.

With alpha-gal, however, it could be hours — three to six, or more — before hives or a rash develop, or you start to feel lightheaded and short of breath. Other common warning signs include indigestion, nausea, vomiting, diarrhea and severe stomach pain.

This delay can make it difficult for people to make the connection between what they ate and their symptoms, Commins says. To complicate matters even more, some people experience only gastrointestinal (GI) symptoms, which is easy to blame on food poisoning or a stomach bug.

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