Alpha-Gal Syndrome: A Tick Bite That Could Make You Allergic to Red Meat

A growing number of Americans are developing a serious, sometimes life-threatening allergy to red meat, and it all starts with a tick bite. Alpha-gal syndrome, triggered primarily by the lone star tick, causes the body to react to a sugar molecule found in the meat of some mammals, and in certain medications as well.

Thomas Hart, a researcher at the Johns Hopkins Bloomberg School of Public Health, says the illness works by confusing the immune system. "That can kind of confuse our bodies and make us recognize the sugar as a foreign threat," Hart said, "and so in that case, it makes us allergic to the sugar and thus allergic to red meat."

The CDC estimates as many as 450,000 people in the United States have the condition, though the true number is likely higher. Because cases aren't required to be reported, many go undiagnosed.

Symptoms can appear after eating red meat or dairy and include hives or an itchy rash, swelling of the mouth or eyelids, nausea, vomiting, diarrhea, indigestion, coughing, difficulty breathing, dizziness, a drop in blood pressure, and in serious cases, full anaphylaxis.

Hart says the illness is spreading partly because the ticks are too. "These ticks are everywhere," he said. "They're spreading rapidly with climate change and with land use change."

The best defense, Hart says, is avoiding a bite in the first place. Treating clothing with permethrin insecticide and applying bug spray can help. After spending time outdoors, check your body thoroughly, paying special attention below the waist and belt line, where lone star ticks tend to bite. Don't forget to check pets as well, since they can carry ticks inside. Showering after outdoor activity can also help rinse off any ticks you may have missed.

If you do find a tick has bitten you, Hart says the next step is clear: "Definitely go to the doctor."