Paul Guyre got home from his lab one evening about 15 years ago and found his wife, Veronica, covered in hives from head to toe. She was too weak to get to her inhaler.
“She lived to tell about it,” Guyre said. “But it was really horrible.”
The culprit: She had eaten meatloaf four hours earlier. She was suddenly allergic to meat.
Guyre is a professor emeritus of microbiology and immunology at Dartmouth’s Geisel School of Medicine, and even he didn’t connect his wife’s condition to her meal right away. That’s the puzzling part about alpha-gal syndrome, a tick-borne allergy to red meat and nearly everything else that comes from a mammal. The reaction arrives hours after the meal.
“The key thing about alpha-gal is you don’t connect the dots so easily,” Guyre said.
What happened to Veronica is far more likely to happen to an Upper Valley resident today than it was 15 years ago. The tick that carries the allergy is the same one that carries Lyme disease, and Vermont counted more ticks and more of their diseases in 2025 than in any year on record. The CDC estimates as many as 450,000 Americans may have alpha-gal, most undiagnosed. This summer, Dartmouth researchers found that the same antibody can turn a routine blood transfusion into an emergency.
Alpha-gal is a sugar found in beef, pork, lamb, dairy and the gelatin that coats many pill capsules. Humans are the only mammals that don’t make it, so our immune systems already treat it as foreign. A tick bite can push that reaction into overdrive: some ticks carry alpha-gal in their saliva, and in a minority of people, the immune system responds by producing IgE, the antibody class behind allergies. After that, a hamburger can trigger a life-threatening reaction hours after the sugar has been digested.
Guyre was able to identify what was happening because he was an immunologist. Their primary care doctor had never heard of the condition. That hasn’t changed as much as it should have. In a 2023 CDC survey, 42% of the health providers surveyed had never heard of alpha-gal syndrome. Diagnosis has sped up: a 2025 study from the CDC and a North Carolina allergy clinic found recent patients were diagnosed in about a month, whereas a decade earlier it took more than five years. A third of patients still waited over a year.
No treatment existed back then, and none exists now. Instead, Guyre and his wife used what he called a “tincture of time.” Some people’s antibody counts drop low enough over time that the reactions stop. Veronica did not eat meat for seven years. Some can never eat meat again.
Veronica was a nurse and an avid hiker, paddler and skier, and she took the diet in stride. She died recently of pancreatic cancer, unrelated to any of this.
“She was tough. She said it wasn’t a big deal,” Guyre said. “And she was actually rubbing my nose in the fact that I had a healthier diet now.”
Her reactions in those years didn’t come from the dinner table.
“It was due to gelatin-containing pharmaceuticals,” Guyre said. “That’s, I guess, how we learned that that was a problem.”
Guyre suspects a deer tick did it, the ordinary kind common across the Northeast, not the Lone Star tick usually blamed for alpha-gal. That is no longer a fringe idea.
That matters here, because the deer tick is the one the Upper Valley has in abundance.
The woods, and who lives near them
When Dr. Jeffrey Parsonnet arrived at Dartmouth Hitchcock Medical Center in 1990, ticks this far north mostly carried nothing. Lyme was still a coastal problem.
Today, “most ticks harbor the organism all the way up to the Canadian border,” said Parsonnet, an infectious disease specialist.
Vermont counted 2,246 cases of Lyme disease in 2025, the most it has ever recorded, according to the Vermont Department of Health, which says its three most common tick-borne illnesses all hit record highs that year. Anaplasmosis, which produced three or fewer cases a year as recently as 2010, had more than 700. More than half the blacklegged ticks the state has tested carried at least one pathogen. Across the river, New Hampshire has one of the highest rates of Lyme disease in the nation, according to the CDC, though the state’s own counts for anaplasmosis and babesiosis are incomplete for the last two years.
Alpha-gal syndrome is the newest entry on that list, and the only one that isn’t an infection. The CDC counted more than 110,000 suspected cases nationally between 2010 and 2022 and estimates as many as 450,000 Americans may have it, most undiagnosed.
What makes this more than an inconvenience is who lives here. Windsor County’s median age was 48.5 at the 2020 census, and nearly a quarter of residents were 65 or older. Parsonnet said he generally resists alarmism, then said this is a case where concern is earned.
“Babesiosis can be severe, especially in people with compromised immune systems and in the elderly,” he said. And when clinicians say elderly, he added, they aren’t describing frail 85-year-olds. Immune function starts slipping in a person’s 50s and 60s.
He put alpha-gal and babesiosis above Lyme on his own list of worries. Lyme is treatable. Alpha-gal has no fix.
“What is this going to do to our eating habits?” Parsonnet said. “What’s it going to do to the beef industry and the pork industry?”
It is common enough on Martha’s Vineyard that restaurant menus mark safe dishes “AG,” and when patients tell Parsonnet they’re spending the summer there, his advice is blunt.
“I say no. Don’t do that. Go swimming in the Amazon,” Parsonnet said. “That’s much safer than going to the Cape.”
The patient on the table
That was the version of alpha-gal syndrome doctors understood: a food allergy, frightening but manageable once you knew what to avoid. This summer, Dartmouth researchers described a second risk. It doesn’t come from a plate. It comes in a bag of platelets, and the people at risk have no idea they’re carrying the allergy at all.
In 2025, a man was on the table for heart surgery at Dartmouth Hitchcock when he “got a Group B platelet product,” said Dr. Richard Kaufman, a pathologist at the hospital, “and immediately dropped his blood pressure in the operating room.”
He was having a severe allergic reaction. His surgeons brought him back. Nothing they had done explained it.
His blood was type O. The sugar that marks blood as type B is so similar to alpha-gal that his antibodies couldn’t tell the difference. Kaufman ordered the test that confirmed it: the patient was positive for alpha-gal IgE. The reaction “was consistent with an anaphylactic, a really severe allergic reaction,” he said.
The patient had a history of tick bites. But he had never had trouble eating red meat, the usual sign of alpha-gal syndrome, so no one had thought to test for it.
Kaufman knew what to look for because Dr. Michael Knudson, a pathologist at the University of Iowa, proposed in 2022 that alpha-gal antibodies might cross-react with type B blood after a few case reports pointed that way. Knudson would become a co-author of the Dartmouth study.
The researchers looked for a pattern: if the hypothesis held, reactions to type B products should cluster in regions where tick bites have sensitized many people and stay flat everywhere else.
Kaufman, with Dartmouth colleagues Nancy Dunbar and Anne Hoen, pulled records of more than half a million platelet and plasma transfusions from 40 hospitals in five countries, sorting the hospitals in advance by whether alpha-gal syndrome is common nearby. Reactions were rare: about three in every thousand transfusions.
They weren’t evenly spread. At the nine U.S. hospitals in regions where alpha-gal syndrome is common, a group that included Dartmouth Hitchcock, type O patients given type B or AB units were nearly four times as likely to react as type O patients given type O units, according to the study published Aug. 24 in JAMA Internal Medicine. At the 15 U.S. hospitals in places where the ticks don’t live, most in the West, and at the hospitals overseas, the pattern was absent.
The study is epidemiological, Kaufman said, and can’t prove the mechanism. It shows a pattern that matches what the hypothesis predicted.
He suspects the transfusion risk reaches more people than the meat allergy does. Only about 1% of those carrying the antibody ever react to meat. Of the nine transfusion cases in the literature, most of the patients, like the man at Dartmouth Hitchcock, could eat a steak without trouble. They had no reason to know.
“It’s just that you’re much more likely to eat a hamburger than you are to get a platelet,” Kaufman said.
What hospitals are doing
Platelets and plasma have never worked the way red blood cells do. A type O patient needs type O red cells, but platelets and plasma could go to anyone, which is how blood banks avoided throwing out units that expire in five days.
“We’ve gone a step further at Dartmouth to say, okay, if someone’s type O, we’re just going to avoid giving them any B or AB platelets or plasma unless we absolutely have to,” Kaufman said, with an exception for bleeding emergencies. Dartmouth Health announced the change alongside the study. Other hospitals have made similar changes.
The cost is waste. “We may end up having to discard some platelet units because we can’t just give them to anybody like we had been doing,” Kaufman said.
The product hospitals now need most is the one already hardest to keep on the shelf. “Type O, O positive and O negative, tend to be in greatest demand,” said Jennifer Costa, regional communications director for the American Red Cross, which supplies about 40% of the nation’s blood, “and so those are typically the first to be depleted.”
Platelets are the harder ask: a two-and-a-half- to three-hour process at a donation center, with a needle in each arm, for a product that lasts five days. “Those platelets have such a short shelf life that there’s always a greater need than the donations coming in,” Costa said.
Kaufman said Dartmouth Hitchcock’s own supply has held, helped by multiple suppliers and a hospital-based donor program.
What nobody knows yet
How many people in the Upper Valley carry the antibody is anyone’s guess. Fourteen states now require doctors and labs to report alpha-gal cases, and six more accept reports voluntarily. Neither Vermont nor New Hampshire does either, and alpha-gal was left off Vermont’s list of reportable diseases when the state revised it in June. Massachusetts began a one-year trial of mandatory reporting on April 1.
There is no alpha-gal support group in the Upper Valley. The nearest in-person groups are on Martha’s Vineyard and, as of this month, in Branford, Connecticut.
No one knows what share of antibody carriers would react to a transfusion.
“For this allergy related to blood transfusion, we’re just defining the problem now,” Kaufman said.
Guyre’s wife had an immunologist in the house. The man on the operating table had a surgical team that happened to include a pathologist who had read the right paper. Neither of them had any way of knowing before the hives, or the crash, that a tick had changed how their bodies worked.
For everyone else, the signal is the delay. Hives, stomach cramps or trouble breathing that arrive in the middle of the night, hours after a dinner of beef, pork or lamb, are the pattern doctors look for, especially in someone who spends time outdoors and has pulled off ticks.
If you think you may have alpha-gal, ask your doctor for the antibody blood test by name. If you already have it, tell your surgeon before an operation. If a reaction reaches your throat or affects your breathing, call 911.
In the Upper Valley, the only way most people find out is the hard way.
