A bug can turn you into a vegetarian, or at least make you swear off red meat. Doctors across the nation are seeing a surge of sudden meat allergies in people bitten by a certain kind of tick.
This bizarre problem was discovered only a few years ago but is growing, as the ticks spread from the Southwest and the East to more parts of the United States. In some cases, eating a burger or a steak has landed people in the hospital with severe allergic reactions.
Few patients seem aware of the risk, and even doctors are slow to recognize it. As one allergist who has seen 200 cases on New York’s Long Island said, “Why would someone think they’re allergic to meat when they’ve been eating it their whole life?”
The culprit is the Lone Star tick, named for Texas, a state famous for meaty barbecues. The tick is now found throughout the South and the eastern half of the United States.
Researchers think some other types of ticks also might cause meat allergies; cases have been reported in Australia, France, Germany, Sweden, Spain, Japan and Korea.
Here’s how it happens: The bugs harbor a sugar that humans don’t have, called alpha-gal. The sugar is also is found in red meat — beef, pork, venison, rabbit — and even some dairy products. It’s usually fine when people encounter it through food that gets digested.
But a tick bite triggers an immune system response, and in that high-alert state, the body perceives the sugar the tick transmitted to the victim’s bloodstream and skin as a foreign substance, and makes antibodies to it. That sets the stage for an allergic reaction the next time the person eats red meat and encounters the sugar.
It happened last summer to Louise Danzig, 63, a retired nurse from Montauk, eastern Long Island, N.Y. Hours after eating a burger, “I woke up with very swollen hands that were on fire with itching,” she said. As she headed downstairs, “I could feel my lips and tongue were getting swollen,” and by the time she made a phone call for help, “I was losing my ability to speak and my airway was closing.”
She had had recent tick bites, and a blood test confirmed the meat allergy. “I’ll never have another hamburger, I’m sure,” Ms. Danzig said. “I definitely do not want to have that happen to me again.”
Erin McGintee, an allergy specialist on eastern Long Island, an area with many ticks, has seen nearly 200 cases over the past three years. At least 30 involved children, and the youngest was 4 or 5. She is keeping a database to study the illness with other researchers.
“It is bizarre,” Dr. McGintee said. “It goes against almost anything I’ve ever learned as an allergist,” because the symptoms can occur as long as eight hours after eating meat, rather than immediately, and the culprit is a sugar — a type of carbohydrate — whereas most food allergies are caused by proteins, she said.
Allergic reactions can be treated with antihistamines to ease itching, and more severe ones with epinephrine. Some people with the allergy now carry epinephrine shots in case they are stricken again.
Doctors don’t know if the allergy is permanent. Some patients show signs of declining antibodies over time, although those with severe reactions are understandably reluctant to risk eating meat again. Even poultry products such as turkey sausage sometimes contain meat byproducts and can trigger the allergy.
The meat allergy “does not seem to be lifelong, but the caveat is, additional tick bites bring it back,” said Scott Commins, who co-authored in 2011 the first paper tying the tick to the illness.