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 a few years ago and 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.

Few patients seem aware of the risk, and 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. 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.

It happened last summer to Louise Danzig, a 63-year-old retired nurse from Montauk on eastern Long Island.

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.

In Mount Juliet near Nashville, Tenn., 71-year-old Georgette Simmons went to a steakhouse June 1 for a friend’s birthday and had a steak. “About 4:30 in the morning I woke up and my body was on fire,” she said. “I was itching all over, and I broke out in hives. Nothing like that had ever happened to me before.”

Dr. Robert Valet at Vanderbilt University said Simmons was one of two patients he diagnosed with the meat allergy that day.

At the University of Virginia in Charlottesville, “I see two to three new cases every week,” said Dr. Scott Commins, who with a colleague, Dr. Thomas Platts-Mills, published the first paper tying the tick to the illness in 2011.

Doctors don’t know whether the allergy is permanent. Some patients show signs of declining antibodies over time.

The meat allergy “does not seem to be lifelong, but the caveat is, additional tick bites bring it back,” Commins said.