Deadly meat allergies from tick bites are on the rise. Should you be worried?

Tick season is booming, and with it come fears over a potentially deadly tick-borne allergy to meat.

Discovered just under 20 years ago, alpha-gal syndrome is caused by bites from the lone star tick in the U.S., though other ticks can trigger the illness in other parts of the world. At least one person is known to have died because of the disease, but scientists know relatively little about it—including how to best treat it. Now researchers have met for the first-ever scientific conference dedicated to alpha-gal to try to tease out some answers.

Physician Scott Commins of the University of North Carolina School of Medicine, who helped discover alpha-gal syndrome, spearheaded the organization of the event, which took place on July 7 and 8. The aim, he says, is to develop “a national set of priorities” for research, funding and education as cases continue to rise.

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Alpha-gal syndrome has long been considered a rare disease in the U.S., but a quick search online suggests it is very much at the fore of the public consciousness: there are scores of alpha-gal support groups on Reddit and Facebook, while some TikToks on the condition have tens of thousands of “likes.”

The most popular alpha-gal Facebook group, “The AlphaGal Kitchen,” has 82,000 members—more than 4,000 than there were just two weeks ago, says Sharon Forsyth, executive director of the Alpha-gal Alliance and the Alpha-gal Alliance Action Fund.

A 2023 U.S. Centers for Disease Control and Prevention study found that, between 2010 and 2022, the number of suspected alpha-gal cases increased each year. An estimated 450,000 people have the disease, according to the CDC, but that may be an underestimate. In a study published on July 2, around one in four people in Arkansas, Kentucky, Missouri, Tennessee and Virginia tested positive for the antibody associated with alpha-gal syndrome, although not all of them were symptomatic.

Despite the growing caseload and heightened public awareness since alpha-gal’s discovery, researchers don’t know a lot about the syndrome.

What we do know is that lone star tick and other ticks can carry the alpha-gal molecule, which is naturally present in the tissues of many mammals but not humans or other primates. A tick bite can inject the molecule straight into the bloodstream, triggering an immune system response. This response produces a certain antibody that causes an allergic when the affected person eats red meat or other meat-related products, such as dairy or gelatin.

At the two-day alpha-gal conference, co-hosted by the University of North Carolina at Chapel Hill, North Carolina’s Department of Health and Human Services and the CDC, speakers and panels discussed everything from tick populations to the syndrome’s impact on heart valves to gastrointestinal issues.

“There’s nothing else that would bring a veterinarian, a physician, an entomologist and an epidemiologist all to the same room with knowledge about the same syndrome,” Commins says.

In part, the risk of alpha-gal is an ecological problem. Lone star ticks’ main diet consists of the blood of white-tailed deer, the population of which has skyrocketed thanks to conservation efforts and the reforesting of the East Coast after the industrial revolution.

“We’ve brought white-tailed deer back from the brink of extinction,” says Holly Gaff, a biology professor at Old Dominion University, who presented at the conference. “When we bring back deer, we bring back their parasites, and then we’re surprised when it happens in our own yards.”

“We’ve created this perfect ecology for the lone star ticks to explode,” she says.

The lone star ticks’ range is also expanding. While they were once relatively sequestered to the U.S. Southeast, the arachnids have begun to spread west and north as white-tailed deer have also spread and the climate has warmed, Gaff says.

As tick interactions increase, so does public—and clinical—awareness of the disease. It’s “absolutely unambiguous” that diagnoses are on the rise, alpha-gal syndrome awareness advocate Forsyth says.

But alpha-gal syndrome is unpredictable, which can make it hard to identify.

In some people, the immune response to alpha-gal looks like an allergic reaction to red meat—yet the symptoms don’t happen right away. It can take hours for hallmarks such as hives, nausea or trouble breathing to manifest. After eating mammalian products, some people with the syndrome experience gastrointestinal problems that can be mistaken for food poisoning or irritable bowel syndrome. Others still can eat red meat with no problems, but if they take medication that contains the alpha-gal molecule, for example, or receive a new heart valve made from a pig or cow, they’ll have a reaction.

Because the syndrome presents so differently among those affected, Forsyth says, she often acts as a helpline for people with questions about the syndrome.

“Right in the middle of the conference, I got a call from someone who has a medical procedure tomorrow,” she says. “I’m not a doctor, and I have no medical background. But they have no one to tell, and they just found out their doctor is going to use heparin, which is derived from pig lungs or intestines. So I have to tell them, ‘Here’s some papers you can take to your doctor, and then you have to trust them to do a risk-benefit analysis.”

Forsyth is also advocating for policy that would formally recognize alpha-gal as a major allergen and require changes to food and drug labeling. Most pharmaceutical companies, she says, don’t clarify whether their products contain alpha-gal.

Researchers don’t know why some people experience such a range of symptoms—or none at all—or what exactly about the tick’s saliva causes these different reactions. Commins’s team hopes better understanding of the tick’s bites and their affect on the body could lead to more human clinical trials for alpha-gal syndrome and perhaps even a vaccine.

For a field that contains so many different silos of research, Gaff says, she appreciated the “multidisciplinary nature” of the conference.

“As researchers and as patient groups, we have our own worlds, and so to bring us together is brilliant.”