Aug. 12, 2014 at 10:39 AM ET
Carnivore no more? Doctors are seeing more and more people who have developed allergies to red meat after being bitten by a tick that has become a fixture in the eastern United States.
A bite from the lone star tick can prompt such a severe reaction to meat that people are even landing in the hospital.
“Classically three to six hours after eating red meat [a person with the allergy] can get with hives, swelling and problems breathing,” says Dr. Robert Valet, an assistant professor of allergy and immunology at Vanderbilt University. “They may even have a full anaphylactic reaction in which their airways close.”
Scientists believe the allergy to red meat is caused by a sugar called alpha-gal passed from the lone star tick to its victims during the bite. Once the sugar enters the blood stream, it can be flagged by the immune system as an invader which results in antibodies being formed against it.
The problem is alpha-gal is found in all red meats, including beef, pork and venison. When the sugar is consumed as food, the stomach just breaks it down, explains Dr. Amesh Adalja, an infectious disease specialist at the University of Pittsburgh Medical Center.
“It’s an interesting mechanism,” Adalja says. “It’s really the reverse of what we’re doing when we give allergy shots. When you get a tick bite, it primes the immune system by exposing the blood to this sugar — and that allows the allergy to develop.”
Right now no one knows whether how long the allergy will last, Valet says. “Anecdotally, there are some patients in whom it does resolve,” he adds. “The most important thing you can do if you develop the allergy, along with avoiding red meat, is to avoid more tick bites since the number of antibodies will rise if there are more tick bites.”
As it turns out, meat allergy isn’t the only damage the lone star tick can cause.
They are also known to spread several serious bacterial infections, such as ehrlichiosis and the potentially deadly tularemia.
Symptoms usually appear within 30 days of a bite and can include:
Treatment is typically with oral antibiotics, although it's unclear whether medication helps recovery, according to the Centers for Disease Control and Prevention.
Ultimately the best advice experts can offer is avoid getting bit by ticks by staying out of brush areas.
“It underscores the importance of checking your body for ticks when you come in from the outdoors,” Adalja says. “And wearing clothing that can protect you from ticks landing on your skin.”
Linda Carroll is a regular contributor to NBCNews.com and TODAY.com. She is co-author of "The Concussion Crisis: Anatomy of a Silent Epidemic”and the recently released “Duel for the Crown: Affirmed, Alydar, and Racing’s Greatest Rivalry”