A little-known allergy is spreading throughout the U.S. It’s called alpha-gal syndrome, is triggered by a tick bite, and has made thousands of people (including Katie's brother, Johnny) allergic to red meat. According to one study, the number of people with the alpha-gal antibody has increased 100-fold from 2013 to 2024.
Here’s what you need to know about the condition — and what's causing this precipitous rise.
What is alpha-gal syndrome?
Alpha-gal is a sugar that’s found in beef, pork, venison, milk — and tick spit. The substance isn’t usually an issue for most people when they’re eating a burger or downing a plate of ribs. But researchers think that when a tick bites someone, it puts their immune system on high alert. The body then identifies alpha-gal as a potentially dangerous foreign substance and creates antibodies that target the sugar, so the next time that person has a hot dog, they could break out into hives, experience nausea, vomiting, or diarrhea, or see their throat, tongue, or lips swell. Johnny's doctor even suggested he carry an EpiPen, because if he were to accidentally have red meat there's a chance he could go into anaphylactic shock.
For some, it's not just beef, pork, and meat from other mammals that becomes off limits. Alpha-gal can also cause a reaction to dairy, or even foods containing gelatin. The odd thing is that people don’t usually feel unwell until hours after their meal, says Theresa MacPhail, Ph.D., author of the new book, Allergic. Most allergic reactions to food occur just minutes after exposure, which is why scientists believe many people might not even realize they’re allergic to red meat at all.
It’s recommended that those with alpha-gal change their diet to cut out meat, carry epinephrine, and avoid tick bites.
How long does alpha-gal syndrome last?
There's no known treatment for alpha-gal syndrome, and it can be a lifelong condition. But it's common for the levels of alpha-gal antibodies to fall over time and for the allergy to fade. According to the Mayo Clinic, some with the allergy can eat meat after 1 to 2 years. However, it's crucial people with the allergy aren't re-bitten by a tick, Scott Commins, M.D., Ph.D., a University of North Carolina researcher studying the syndrome, told the Associated Press.
“The tick bites are central to this,” he said. “They perpetuate the allergy.”
How common is alpha-gal syndrome?
According to the Centers for Disease Control, nearly 500,000 Americans are living with the allergy, although the agency says "emerging evidence suggests the true number may be significantly higher."
They say the allergy’s probably undercounted because it’s so new; the syndrome wasn't discovered until around 2007 by Dr. Thomas Platts-Mills, a prominent allergist and immunologist at the University of Virginia. In a survey of 1,500 primary care doctors, the CDC found that about half had never heard of the condition, and only 5 percent said they felt confident diagnosing it. And as we mentioned earlier, the reaction is so belated that patients might not even connect their upset stomach to their steak dinner.
The allergy is most common in the eastern and southern U.S., where a specific variety of tick, called the lone star tick, is found. The pest is the best known for spreading alpha-gal syndrome, but it’s thought that others can too. According to the Associated Press, cases have been reported in Australia, France, Germany, Japan, and other countries where lone stars aren’t present.
Why are rates of alpha-gal rising?
Experts say it’s partly because more doctors are becoming aware of the allergy and are ordering their patients to get tested. But there’s evidence that climate change is to blame too, Dr. MacPhail tells us.
Warmer temperatures have allowed the parasites to expand their territory and move further north. They’ve now been found as far as Canada, she says. The milder winters also mean that fewer ticks are being killed off, which has caused the population to explode. The heat and pollution has also changed the composition of our forests, providing more cover for critters, which is like a “smorgasbord for ticks,” Dr. MacPhail says.
“It’s a whole lot of things changing, which have led to rising tick populations,” she says. (We spoke to Dr. MacPhail about how climate change has super-charged other allergens too.)
