When you become allergic to meat
A tick-borne syndrome that triggers an allergy to meat and animal products is spreading throughout the southeastern U.S. and the world, said journalist Maryn McKenna. It has doctors baffled—and worried.
I T IS EARLY morning in early summer, and I am tracing my way through the woods of central North Carolina, steering cautiously around S-curves and braking hard when what looks like a small rise turns into a narrow bridge. I am on my way to meet Tami McGraw, who lives with her husband and the youngest of their kids in a sprawling development of old trees and wide lawns just south of Chapel Hill. Before I reach her, McGraw emails. She wants to feed me when I get there: “Would you like to try emu?” she asks. “Or perhaps some duck?” These are not normal breakfast offerings. But for years, nothing about McGraw’s life has been normal. She cannot eat beef or pork, or drink milk or eat cheese, or snack on a gelatincontaining dessert without feeling her throat close and her blood pressure drop. Wearing a wool sweater raises hives on her skin; inhaling the fumes of bacon sizzling on a stove will knock her to the ground. Everywhere she goes, she carries an array of tablets that can beat back an allergy attack, and an autoinjecting EpiPen that can jolt her system out of anaphylactic shock.
McGraw is allergic to the meat of mammals and everything else that comes from them: dairy products, wool and fiber, gelatin from their hooves, char from their bones. This syndrome affects some thousands of people in the United States and an uncertain but likely larger number worldwide, and after a decade of research, scientists have begun to understand what causes it. It’s brought on by the bite of a tick—picked up on a hike, or brushed against in a garden, or hitchhiking on the fur of a pet that was roaming outside. The illness, which generally goes by the name “alpha-gal allergy” after the component of meat that triggers it, is a trial that McGraw and her family are still learning to cope with. In much the same way, medicine is grappling with it, too. Allergies occur when our immune systems perceive something that ought to be familiar as foreign. For scientists, alpha-gal is forcing a remapping of basic tenets of immunology: how allergies occur, how they are triggered, whom they put in danger and when.
For those affected, alpha-gal is transforming the landscapes they live in, turning the reli- They sent her for MRI scans, pulmonary function tests, echocardiograms of her heart. Nothing yielded a result. Looking back, she realizes she missed clues as to the source of her problem. She would feel short of breath and need to visit an urgent-care clinic on Saturdays—which always started, in her household, with a big breakfast of eggs and sausages.
Then a close friend had a scary episode, going for a run, arriving home and passing out on the hot concrete of her driveway. Once she had recovered, McGraw quizzed her. Her friend said: “They thought I got stung by a bee while I was running. But now they think maybe I have a red-meat allergy.” McGraw remembers her first reaction was: That’s crazy. Her second was: Maybe I have that, too.
She Googled, and then she asked her doctor to order a little-known blood test that would show if her immune system was reacting to a component of mammal meat. The result was so strongly able comforts of home—the plants in their positive that her doctor called her at home gardens, the food on their plates—into an to tell her to step away from the stove.
T uncertain terrain of risk.
HE SURPRISING STORY of how docIn her memory, McGraw’s symptoms began tors in the U.S. discovered alpha-gal after 2010. That was the year she and her allergy begins with a cancer drug husband, Tom, a retired surgeon, spied called cetuximab, which came onto the a housing bargain in North Carolina in market in 2004. Cetuximab is a protein a development next to a nature reserve. grown in cells taken from mice. For any The leafy spread of streams and woodland new drug, there are likely to be a few peopockets was everything she wanted in a ple who react badly to it, and that was true home. She didn’t realize that it offered for cetuximab. In its earliest trials, one or everything that deer and birds and rodents, two of every 100 cancer patients who got it the main hosts of ticks, want as well. infused into their veins had a hypersensitivShe remembers one tick that attached to ity reaction: Their blood pressure dropped, her scalp, raising such a welt the spot was and they had difficulty breathing. red for months afterward, and a swarm of But there was an aberration. In clinics in baby ticks that climbed her legs and had North Carolina and Tennessee, 25 of 88 to be scrubbed off in a hot bath laced with recipients were hypersensitive to the drug, bleach. Unpredictably, at odd intervals, she with some so sick they needed emergency began to get dizzy and sick. shots of epinephrine and hospitalization.
“I’d have unexplained allergic reactions, At about the same time, a patient who got and I’d break out in hives and my blood cetuximab in a cancer clinic in Bentonville, pressure would go crazy,” she told me. The Ark., collapsed and died after the first dose. necklines of all her T-shirts were stretched, Alpha-gal is familiar to many scientists because she tugged at them to relieve the because it is responsible for an enduring feeling she couldn’t take a deep breath. She disappointment: Its ability to trigger intense trekked to an array of doctors who diagimmune reactions is the reason that organs nosed her with asthma or early menopause taken from animals have never successor a tumor on her pituitary gland. They prefully been transplanted into people. The scribed antibiotics and inhalers and steroids. puzzle was why the drug recipients were