A Tick Bite Made Them Allergic to Meat
And an organ-transplant company has an unexpected solution.
A few months ago, Candice Matthis and Debbie Nichols sat down with their husbands to have some bacon. It was an unremarkable scene, except for two details.
First, there were the EpiPens, which Matthis and Nichols both had ready in case of emergency. The two women can’t eat red meat, not after they were each diagnosed with a dangerous red-meat allergy that develops, oddly enough, after tick bites. They had bonded as friends over their strange shared fate, where a strip of bacon could send them into anaphylactic shock. Matthis is so sensitive that even the airborne particles wafting off a pan of cooking meat typically make her sick. But this time, nothing happened to her as the bacon sizzled. Her EpiPen remained untouched. Nichols made herself a BLT. “It had been years,” she told me. And for her, too, nothing happened, except that she remembered how good a BLT tasted.
Which brings us to the second remarkable thing about the meal. This bacon was not your regular bacon, or even your fancy pasture-raised, thick-cut bacon; this bacon was so exclusive that it’s not available in stores. It came from Revivicor, a biotechnology company that genetically modifies pigs to create organs suitable for transplant into humans. (One of its pig hearts was experimentally transplanted into a human for the first time this January.) It just so happens that the same molecule—a sugar called alpha-gal—that causes the human immune system to reject pig organs also causes the tick-associated red-meat allergy, known as alpha-gal syndrome. To make a pig whose organs could be harvested for transplant, Revivicor first had to make an alpha-gal-free pig. And when it did, the company realized that transplant surgeons weren’t the only ones interested.
Since last fall, Revivicor has been quietly sending refrigerated packages of alpha-gal-free bacon, ham, ground pork, chops, and pork shoulders to people in the alpha-gal-syndrome community. These packages were free, but Revivicor has told the FDA it is exploring a mail-order business. And so a biomedical company has found itself an accidental purveyor of specialty pork products.
Alpha-gal syndrome is an unusual allergy with an unusual history, even before genetically modified bacon entered the picture. It was considered a rare curiosity when it was first discovered in 2008. Since then, the true prevalence of alpha-gal syndrome has begun to reveal itself; tens of thousands of Americans likely have it. And the tick species that causes this syndrome, the Lone Star tick, is spreading across the United States too. Exactly how the bites of the Lone Star tick trigger this specific immune reaction to alpha-gal is still unknown. One hypothesis is that the tick’s saliva also contains the sugar molecule.
Although sometimes shorthanded as an allergy to red meat, alpha-gal syndrome is more accurately called an allergy to mammalian products. The molecule is found in the bodies of nearly all mammals other than primates, where it likely functions as a molecular tag. It is in muscle and fat, which means steaks, bacon, and lamb chops are obvious no-no’s for people with alpha-gal syndrome. But for people who are more sensitive to alpha-gal, dairy can also trigger a reaction. And for the small minority who are the most sensitive, avoiding alpha-gal means hunting for mammalian by-products hiding in the most unexpected places: drug capsules and candy (which can contain gelatin), face creams (collagen), and lip balm (lanolin). Even a wool sweater can make some people break out in hives.
To avoid alpha-gal, Matthis and Nichols—who blog about alpha-gal syndrome as the Two Alpha Gals—had to dramatically restructure their diets and their lives. “I was a huge Paleo person,” says Matthis, which obviously wasn’t going to work anymore. She eventually went vegan.
Her entire family had to give up red meat at home because of her sensitivity to meat fumes. “They went through their own mourning,” she told me. It was hard, but they understood the danger; her teenage children have had to take her to the ER in anaphylactic shock. Eating in restaurants is a total minefield, so she packs a cooler of safe foods when she travels. Nichols, for her part, went on a cruise a few months after she was first diagnosed, thinking she could just avoid beef, pork, and dairy. She woke up in the middle of the night in what she now understands to have been anaphylaxis. In retrospect, she must have accidentally eaten something of mammalian origin. She remembers pacing the top deck, trying desperately to breathe, and waking a nurse, who did not believe that she had such an allergy. “I’m never going on a cruise again,” she told me. “Never!”
Skepticism from doctors and nurses is unfortunately not uncommon. Alpha-gal syndrome doesn’t quite look like typical food allergies, says Scott Commins, an allergist at the University of North Carolina who originally helped discover the syndrome back in 2008. The symptoms usually appear hours after eating rather than immediately. “At 2 a.m., no one really in the ER thinks to ask what you had for dinner at 8 p.m.,” he told me. “The delay is a big issue.” And while some people have classic allergy symptoms such as hives and swelling of the lips and tongue, others tend to have gastrointestinal issues, including abdominal pain and diarrhea. A diagnosis requires a test for antibodies against alpha-gal. Some patients told me they had a relatively easy time getting the test; others had to deal with doctors totally unfamiliar with alpha-gal. “Living in Nevada, nobody really has alpha-gal [syndrome] unless they moved here,” says Ilana Short, who lives in Las Vegas now but grew up in Tennessee. (Lone Star ticks are currently found in the eastern, southern, and midwestern United States, though they have been moving west.) She had unexplained hives for years before she was finally diagnosed.
Commins first got in touch with Revivicor years ago when he was looking into alpha-gal-free pigs as an experimental model to study the allergy. Revivicor, for its part, was not founded with niche food allergies in mind. It is and has always been focused on the goal of xenotransplantation, or animal-to-human organ transplants. Alpha-gal happens to be one of the biological obstacles to that goal. Because human bodies don’t naturally produce this molecule, its presence on, say, a pig organ causes immune rejection. To get around this, Revivicor had to create a pig lacking a functional gene for alpha-gal. If this strategy to get around the immune system worked for transplants, it could work for food allergies too.
Again, Revivicor was focused on transplants. “We didn’t at first think there were enough patients with alpha-gal syndrome to really be a blip on their radar screen,” Commins told me. But over time, the community of people with the syndrome has grown larger and larger. They joined Facebook groups to swap information and tips and recipes. And some of them started reaching out to Revivicor about its alpha-gal-free pigs.
One of these people with alpha-gal syndrome happened to be Steve Troxler, who is, ironically enough, the agriculture commissioner of North Carolina, one of the top hog-producing states in the nation. “Part of my job as a commissioner of agriculture is to be able to eat more barbecue than any human being on the face of the Earth,” he says, which became rather awkward when he developed the allergy in 2017. When Troxler heard about Revivicor, he saw the benefit both for people with alpha-gal syndrome and, potentially, for North Carolina. He sprang into action.
With his decades of agriculture-industry experience, Troxler knew which people at the FDA to introduce the company to and how to navigate the complex regulatory process. “It kind of became a part of my life’s work to try to help get this product to the market,” he told me. The agency took 20 years to approve the first genetically modified animal for food, the AquaBounty salmon. Troxler was proud to help get Revivicor’s pig—only the second genetically modified food animal—approved in a relatively speedy two years. In December 2020, the FDA gave Revivicor’s GalSafe pig an official stamp of approval. (These pigs are not, by the way, the exact same pigs whose organs were used in the much-publicized pig-heart transplant or in two recent kidney transplants into brain-dead patients. Xenotransplantation requires a suite of additional genetic modifications to minimize rejection and make the organs comparable in size to humans’.)
The original herd of GalSafe pigs at the time of approval was small—reportedly numbering just 25. And Revivicor still has a long road to travel to commercial availability. The pigs are currently raised at a facility in Iowa, but Troxler hopes to set up a bigger production plant in, of course, North Carolina, with the alpha-gal-free pork hitting the market in 18 months. Revivicor has been very tight-lipped about its plans for commercializing GalSafe pork. The company, which rarely grants media interviews, declined to comment for this story.
Late last year, though, the company began offering free samples of GalSafe pork products in limited quantities. An order form began to circulate among the alpha-gal support groups on Facebook. Amber Shifflett received her order of four ham steaks and four packs of ground pork last fall. She had had to give up her beloved steaks and bacon breakfasts when she was diagnosed with alpha-gal syndrome earlier in the year. Now she has carefully rationed her precious stock of alpha-gal-free pork. She ate the ham steaks for Christmas. “That was my Christmas present to myself,” she told me. The ground pork is still in her freezer, waiting for a special occasion. “I’m so hesitant because they’re the last of my samples,” she said. Maybe she’ll have them for a cookout this summer, when everyone else is chowing down on red meat. She is still researching the right recipe.
The half-dozen people I talked with who tried the Revivicor meat all had good experiences. Troxler, in his expert opinion, said the pork tasted just like normal pork. No one had allergic reactions. “The only bad thing is it reminded me how delicious pork is,” says Sharon Forsyth, who has had the syndrome for three years and runs the site Alpha-gal Information. Scott Commins is about to begin a study, funded by Revivicor, to formally confirm the pork’s safety for people with alpha-gal syndrome, because the FDA approval was just for general consumption.
As nice as it was to taste pork again, those who tried Revivicor’s pork told me, it didn’t solve the challenges of living with alpha-gal. Some missed eating bacon more than others, but they all missed the carefreeness they hadn’t known they’d once enjoyed. “I miss being able to have a normal life,” Forsyth said. “I miss being able to travel. I miss being able to eat out without it always being an ordeal.” One of her good friends lives in Madagascar, but she can’t fathom traveling to a country where she doesn’t speak the language and where she would have to ask about the presence of meat and dairy and hidden mammalian ingredients such as gelatin in everything she used or ate.
It’s not just food and personal care products she worries about. Mammalian by-products are also used widely in medicine: Replacement heart valves come from pigs or cows; vaccines can contain additives such as glycerin or bovine extract; gelatin is in drug capsules; sutures can have collagen; and monoclonal antibodies can be derived from mammals or mammalian cell lines. In fact, one of the first pieces of evidence that clued scientists in to alpha-gal syndrome was when cancer patients in areas with ticks started reacting to a mouse-derived monoclonal-antibody treatment. Most people with alpha-gal syndrome are not so sensitive that they have to avoid all of these medical products, but some are. Imagine that you’re sick in a hospital, Forsyth said, and you have to worry about reacting to not just the food you eat but the drugs you’re given.
But Revivicor’s pigs could offer a safer alternative here, too. “Having pork is great,” Commins said. “But to me it’s really the medical uses of these animals that can be really helpful for patients.” They might not be as sci-fi as transplanting whole pig organs, but alpha-gal-free sutures and heart valves would matter to these patients. The genetically modified pigs that were created for xenotransplant research and then turned into niche pork products might become medical products again.