Why Are so Many People Getting a Meat Allergy?

December 12, 2018

Becoming allergic to meat turns your life upside down. Known as alpha-gal allergy, the condition dictates what you can eat, wear, how you relax, and even which medicines are safe. Is research finally starting to catch up?

It 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 gelatine-containing 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 auto-injecting 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 fibre, gelatine from their hooves, char from their bones. This syndrome affects some thousands of people in the USA and an uncertain but likely larger number worldwide, and after a decade of research, scientists have begun to understand what causes it. It is created 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 reliable comforts of home ­– the plants in their gardens, the food on their plates – into an uncertain terrain of risk.

In 1987, Dr Sheryl van Nunen was confronted with a puzzle. She was the head of the allergy department at a regional hospital in the suburbs of Sydney, Australia, and had a reputation among her colleagues for sorting out mysterious episodes of anaphylaxis. This time, a man had been sent to see her who kept waking up, in the middle of the night, in the grip of some profound reaction.

Van Nunen knew at once that this was out of the ordinary, since most allergic reactions happen quickly after exposure instead of hours later. She also knew that only a few allergens affect people after they have gone to bed. (Latex, for instance – someone sensitive to it who has sex using a latex condom might fall asleep and wake up in the midst of an allergy attack.) She checked the man for the obvious irritants and, when those tests came up negative, took a thorough look at his medical history and did a skin test for everything he had eaten and touched in the hours before bedtime. The only potential allergen that returned a positive result was meat.

This was weird (and dismaying, in barbecue-loving Australia). But it was the only such case Van Nunen had ever seen. She coached the patient on how to avoid the meals that seemed to be triggering his reactions, put it down mentally to the unpredictability of the human immune system, and moved on.

Then a few more such patients came her way. There were six additional ones across the 1990s; by 2003, she had seen at least 70, all with the same problem, all apparently affected by meat they had eaten a few hours before. Groping for an explanation, she lengthened the list of questions she asked, quizzing the patients about whether they or their families had ever reacted to anything else: detergents, fabrics, plants in their gardens, insects on the plants.

“And invariably, these people would say to me: ‘I haven’t been bitten by a bee or a wasp, but I’ve had lots of tick bites,” Van Nunen recalls.

In her memory, Tami McGraw’s symptoms began after 2010. That was the year she and her husband Tom, a retired surgeon, spied a housing bargain in North Carolina, a development next to a nature reserve whose builder had priced the big houses to sell. The leafy spread of streams and woodland pockets was everything she wanted in a home. She didn’t realise that it offered everything that deer and birds and rodents, the main hosts of ticks, want as well.

She remembers one tick that attached to her scalp, raising such a welt the spot was red for months afterwards, and a swarm of baby ticks that climbed her legs and had to be scrubbed off in a hot bath laced with bleach. Unpredictably, at odd intervals, she began to get dizzy and sick.

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