Tick Bites Are Giving More People Alpha-Gal Red Meat Allergy in the US

And the CDC suggests it could get worse.

If you spend time outdoors during the summer, you probably know how important it is to check for ticks to make sure you don’t contract Lyme disease, Rocky Mountain Spotted Fever, or any other tick-borne illnesses. But there’s also a surprising condition spread by ticks that you may not have bargained for when you stepped out for your walk in the woods: an allergy to red meat. That’s right. A bite from the Lone Star tick (Amblyomma americanum) can leave you allergic to beef, pork, lamb, and any other mammal’s meat. And unfortunately, doctors suspect that the condition is becoming more common as the tick’s habitat expands.

In early May, the US Centers for Disease Control and Prevention warned that vector-borne diseases are on the rise, and while this allergy isn’t technically a disease, the rising numbers and expanding ranges of vector bugs will likely contribute to rising numbers of new cases. The condition, which is transmitted through a still-poorly-understood process by the saliva of the Lone Star tick, makes people allergic to galactose-alpha-1,3-galactose — alpha-gal for short — a carbohydrate that’s present in the flesh and organs of most mammals, but not humans.

When someone with the allergy eats mammal meat, their body responds by releasing histamines, much in the same way that someone’s body would respond to other food allergies. This can mean breaking out in hives and experiencing gastrointestinal disturbances in many cases.

The Lone Star Tick is ruining summer barbecues across the United States.

As Inverse previously reported, scientists initially connected the dots to identify tick bites as the source of alpha-gal allergies by comparing data on people who are allergic to a cancer drug called cetuximab with people who are allergic to meat.

People in the southeastern U.S., they found, were 10 times more likely to be allergic to this effective cancer drug. Further investigation showed that the region was also home to people with meat allergies. Since cetuximab and mammal meat both contain alpha-gal, and the affected people’s blood contained alpha-gal antibodies, the researchers hypothesized that the sugar was behind the allergy.
Most scientists agree that allergies occur when a foreign allergen — like alpha-gal — is mistakenly marked as an invader by the antibodies of the body’s immune system, which then releases chemical weapons to destroy it. One of those weapons is histamine, which triggers the inflammation necessary to deal with the allergen — but also causes the rest of your body to swell up, as well.

But even since that discovery, our understanding of the alpha-gal allergy has progressed very slowly. Scientists still don’t quite know how ticks can infect people with an allergy, though some suspect it happens when alpha-gal from a non-human animal gets injected into a human’s bloodstream as a tick feeds, causing the body to produce antibodies as an immune response.

In some cases, an epipen may help alpha-gal allergic people deal with accidentally eating meat.

Vu Nguyen, flickr

Underscoring how far we have to go in understanding this phenomenon, a spokesperson for the National Institute of Allergy and Infectious Diseases tells Inverse that there’s still no system in place for tracking new cases of alpha-gal-related meat allergies. In fact, some researchers say that we may be seriously underestimating the number of cases in the US.

“We’re confident the number is over 5,000 [cases], and that’s in the U.S. alone,” [Scott Commins[(, an allergist and associate professor of medicine at the University of North Carolina, Chapel Hill tells WUNC. “The range of the tick is expanding.”

Commins’ warning, coupled with the CDC’s assessment that ticks’ seasons are getting longer and their ranges getting larger, underscores the need to wear DEET-containing bug repellant and cover up as much as possible when venturing out into the woods or the high grass this summer. Otherwise you may experience some serious FOMO at the barbecue.

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