Hours after savoring that perfectly grilled steak on a beautiful summer evening, your body turns traitor, declaring war on the very meal you just enjoyed. You begin to feel excruciating itchiness, pain or even swelling that can escalate to the point of requiring emergency care.

The culprit isn’t food poisoning – it’s the fallout from a tick bite you may have gotten months earlier and didn’t even notice.

This delayed allergic reaction is called alpha-gal syndrome. While it’s commonly called the “red meat allergy,” that nickname is misleading, because alpha-gal syndrome can cause strong reactions to many products, beyond just red meat.

The syndrome is also rapidly spreading in the U.S. and around the globe. The Centers for Disease Control and Prevention estimates as many as 450,000 people in the U.S. may have it. And it’s carried by many more tick species than most people realize.

Alpha-gal syndrome is actually an allergy to a sugar molecule with a tongue-twisting name: galactose-alpha-1,3-galactose, shortened to alpha-gal.

The alpha-gal sugar molecule exists in the tissues of most mammals, including cows, pigs, deer and rabbits. But it’s absent in humans. When a big dose of alpha-gal gets into your bloodstream through a tick bite, it can send your immune system into overdrive to generate antibodies against alpha-gal. In later exposure to foods containing alpha-gal, your immune system might then launch an inappropriate allergic response.

Often this allergy is triggered by eating red meat. But the allergy also can be set off by exposure to a range of other animal-based products, including dairy products, gelatin (think Jell-O or gummy bears), medications and even some personal care items. The drug heparin, used to prevent blood clotting during surgery, is extracted from pig intestines, and its use has triggered a........

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