Alpha-gal syndrome, also called the 'red meat allergy,' is spreading. Lone star and black-legged ticks are to blame.

Cases of suspected alpha-gal syndrome based on confirmed laboratory evidence. (CDC map via The Conversation)

Despite being unable to jump or fly, ticks are surprisingly good at hiding in vegetation and attaching to people as they walk or hike past. When a tick attaches to a person's flesh and begins to suck blood, the tick injects its saliva -- and anything it contains -- into the person's body. Certain ticks expel alpha-gal sugar molecules into their host's body, which can, months later, leave the person allergic to specific proteins.

"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," writes entomologist Lee Rafuse Haines for The Conversation. Dairy products, gelatin and even some prescription medications can trigger a response.

Alpha-gal syndrome isn't a disease; it's a reaction to the "alpha-gal sugar molecule [that] exists in the tissues of most mammals, including cows, pigs, deer and rabbits. But it’s absent in humans," Haines explains. "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."

Once a person is exposed to the alpha-gal sugar protein through a tick bite, it can take months for an allergic reaction to occur. Syndrome symptoms can "range from hives or swelling to crushing abdominal pain, violent nausea or even life-threatening anaphylactic shock," Haines adds.

Alpha-gal syndrome is commonly blamed on the lone star tick bites, but other ticks can spread it as well. In North America, tick bites from the lone star tick and the black-legged tick, also called a deer tick, can cause alpha-gal syndrome. Scientists are also looking at other species of ticks found in the U.S. as possible culprits.

Even as alpha-gal syndrome spreads in the U.S., not all medical professionals have experience with it. Haines writes, "A study in 2022 found that 42% of U.S. health care practitioners had never heard of alpha-gal syndrome."