NEW YORK (NEWSnet/AP) — More than 100,000 people in the U.S. have become allergic to red meat since 2010 because of a syndrome triggered by tick bites, according to a government report released Thursday. Health officials believe many more have the problem and don't know it.

A second report estimates as many as 450,000 Americans have developed the allergy.

Dr. Scott Commins, a University of North Carolina researcher, co-authored both reports, published by Centers for Disease Control and Prevention.

People with the allergy have described it as bewildering and terrifying.

The reaction, called alpha-gal syndrome, occurs when an infected person consumes meat from mammals or ingests milk, gelatin or other mammal products.

It is caused by alpha-gal, that is in meat from mammals, and in tick spit. When the sugar enters the body through the skin, it triggers an immune response and can lead to a severe allergic reaction.

Scientists had encountered reactions in patients taking a cancer drug that was made in mouse cells containing the alpha-gal sugar. In 2011, researchers found it could spread through tick bites, too.

They tied it to the lone star tick, which, despite its Texas-themed name, is most common in the eastern and southern U.S.

One of the studies released Thursday examined test results from 2017-22 from the main U.S. commercial lab, looking for alpha-gal antibodies. The number of people testing positive rose from about 13,000 in 2017 to 19,000 in 2022.

Experts say cases may be up for a variety of reasons, including the tick’s expanding range, more people coming into contact with the ticks and more doctors learning about it and ordering tests.

The second survey came in 2022, of 1,500 U.S. primary care doctors and health professionals. Nearly half of providers were unaware of alpha-gal syndrome, and only 5% said they felt confident they could diagnose it. Researchers used that information to estimate the number of people with the allergy.

People with the syndrome experience symptoms that include nausea, vomiting, diarrhea, severe stomach pain, difficulty breathing, dizziness and swelling of the lips, throat, tongue or eyelids. Unlike some food allergies, which occur soon after eating, reactions come hours later.

Doctors counsel people with the allergy to change their diet, carry epinephrine and avoid tick bites.

“The tick bites are central to this,” Commins said. “They perpetuate the allergy.”

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