Here's the crazy way it works, plus how to protect yourself.
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Do you normally down burgers, steaks, and other types of red meat and feel just fine when the meal's over? Take note if you break out in hives, experience swelling and itching, or get symptoms like vomiting or diarrhea four to six hours after consuming the stuff: Doctors are beginning to report allergic reactions—even anaphylactic shock—in patients who've recently eaten beef, pork, or lamb, even if they'd never had reactions in the past. The reason? A bite from a kind of tick called the Lone Star could be to blame.

While the Lone Star tick was once mainly prevalent in the Southwest (like in Texas, the Lone Star state), it's been appearing along the Eastern Seaboard in states like North Carolina, Virginia, and all the way up into Maine, according to the Associated Press. With it, doctors have been seeing bizarre cases of this red-meat allergy in numbers going into the thousands, ScienceDaily reports.

The Lone Star tick carries in its gut a sugar called alpha-gal—a sugar that's also found in meat. Experts believe that when a Lone Star tick bites someone, their immune system treats the sugar as an invader and makes antibodies. The next time that person eats red meat, they could have a serious allergic reaction.

Doctors at Vanderbilt University Medical Center say there isn't a good way to treat or reverse this allergy, but so-called alpha-gal patients can safely eat poultry like chicken and turkey.

How to protect yourself: Follow proper tick-prevention behavior when you're out in the woods, especially in the parts of the U.S. mentioned above—i.e. wear long pants and sleeves, and check for bites post-exposure.

And if you notice any strange allergy symptoms after eating your next roast beef sandwich, hit the ER, pronto.

Camille Chatterjee is the Deputy Editor of Health.