Alpha What?

By Peter Galvin, MD

I never cease to be amazed by the size and scope of medicine. I read medical journals regularly in order to stay current, and every now and then, I come across a disease or condition I didn’t know about. The latest one I came across is alpha-gal syndrome. Like Lyme disease, it is associated with tick bites, but from a different tick. Alpha-gal is caused by the painless bite of a Lone Star tick. Aha, you think, it must be a Texas disease, only it’s not. The moniker “Lone Star” refers to a silver-white star-shaped or “lone star” spot on the back of the tick (see photo). It is also known as a northeastern water tick or turkey tick. It lives in wooded areas of the eastern U.S. (approximately from the Mississippi to the Atlantic coast) and Mexico.

When the tick bites a human, it injects a type of sugar molecule (galactose-alpha-1,3-galactose), also called alpha-gal, which leads to the formation of antibodies in the person who was bitten. Because alpha-gal is present on the cells of most mammals, including cows, pigs, lambs, and goats, when affected individuals eat these animal products, an allergic reaction may occur. Alpha-gal allergic reactions can range from mild to life-threatening (anaphylaxis) and typically occur about two to six hours after ingestion of mammalian meat or other mammalian products (like cow’s milk, cheese, and gelatin). Symptoms may include hives; swelling of the lips, tongue, throat, or eyelids; cough; difficulty breathing; wheezing; heartburn; nausea or vomiting; abdominal pain; diarrhea; or decreased blood pressure.

In the U.S., about 110,000 cases of alpha-gal were reported from 2010 to 2022, however many more cases were likely undiagnosed and/or unreported. It is most frequently diagnosed in the southern, central, and eastern U.S., but cases have been reported in other areas of the U.S. and worldwide. It can affect both children and adults. The ticks live in the thick underbrush or forest floor of wooded areas. They move up to the tip of a blade of grass and then extend their front legs, thereby catching, or latching onto, a person walking by. This process is called questing. They also feed on white-tailed deer, rodents, turkeys (hence the name “turkey tick”), and other small mammals and birds. Alpha-gal syndrome can be diagnosed with a blood test to detect the antibodies. Mild symptoms can be treated with antihistamines, while those with severe reactions need to carry an epinephrine injector (Epi-pen) and may require treatment in an ER. Those with alpha-gal need to avoid mammalian meat and mammalian-based products. Some medications, for example blood thinners (heparin), snake antivenom, some cancer medications (cetuximab), and mammal-based organ replacements (such as heart valves) may cause allergic reactions in those with alpha-gal.

The simplest prevention is avoiding grassy, brushy, and wooded areas where ticks live. For those who are outdoors in these areas, they should walk in the center of trails, use EPA-registered insect repellants, and wear clothing that covers all exposed skin. When coming inside, they should check their skin for ticks, and if one is found, use tweezers to pull it out before it becomes engorged. Lone Star ticks can cause a rash similar to Lyme disease and may also carry the heartland virus and tularemia. For more information go to: www.cdc.gov/ticks/alpha-gal/index.html.

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