Two additional tick species can transmit red meat allergies: See where they are

Ticks have been known to transmit diseases to humans, such as Lyme disease, babesiosis or Rocky Mountain spotted fever, but now a recently discovered red meat allergy could become more common.

The red meat allergy, or alpha-gal syndrome, was first reported in 2009 and is still relatively rare. Once a person is bitten and infected, symptoms appear after they eat red meat or if they're exposed to other animal products, the Centers for Disease Control and Prevention said.

Until recently, scientists thought only the lone star tick could spread the disease. But a new study finds bites from two other tick species – the blacklegged tick and Western blacklegged wood tick – can trigger the allergy, too.

Where the three tick species linked to red meat allergies are found

The eastern and southern U.S. is home to the majority of lone star tick populations. The blacklegged tick, also known as the deer tick, is widespread in the East. Western blacklegged wood ticks are found on the West Coast.

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Where alpha-gal syndrome cases have been reported the US

More than 110,000 cases of alpha-gal syndrome were documented in the U.S. from 2010 to 2022, according to CDC data, but the agency estimates up to 450,000 people may have been infected and most didn't report it.

"The overwhelmingly vast majority of cases occur within the range of the lone star tick, which is why most cases of AGS are found in the eastern, southeastern and the south-central parts of the United States," Dr. Johanna Salzer, veterinarian and disease ecologists at the CDC, told USA TODAY in a statement. 

What are the symptoms of alpha-gal syndrome?

Alpha-gal, a sugar molecule, enters the body via a tick bite. In certain people, this sets off a response from the immune system, the body's defense mechanism. Red meats such as lamb, beef and pork can trigger mild to severe allergic responses, according to the CDC. Reactions to other foods that come from animals, such as dairy or gelatins, also can occur.

Ways to prevent tick bites

If you expect to be in an area where ticks live, such a backyard, park or campsite, be extra careful when venturing outside. Ticks can be a year-round annoyance, but they are most active in the warmer months of April through September.

CONTRIBUTING Jim Sergent, Ahjané Forbes and Julia Gomez

SOURCE Centers for Disease Control and Prevention, Mayo Clinic, University of Minnesota and USA TODAY research

This story was updated to add new information.