Story Excerpt

Alpha Gal

by Greg Egan

Elena woke, aching, itching, queasy. She stumbled out of the bedroom without turning on the lights and made it to the toilet in time to relieve the pressure in her bowels, but no sooner was that done than she was vomiting.

She knelt by the toilet bowl, shivering, empty but still wretched. The tiles against her knees were torture, but as she struggled to her feet every other joint and muscle in her body protested just as loudly. In the bathroom, as she rinsed her mouth out, she squinted into the mirror, and realized that she was peering through barely open eyelids, not as a response to brightness but from the swelling around her eyes squeezing them shut.

Her throat was constricted, too; each inhalation was like sucking molasses through a straw. She made her way back to the bedroom. Daniel had already woken and turned on a lamp, but now he rose and approached her, horrified.

“What’s happening?” he asked.

“Call an ambulance.” Elena wasn’t sure if her words were even audible, but Daniel got the meaning straightaway and grabbed his phone. “Some kind of allergic reaction,” he guessed, as the operator quizzed him. “No, we don’t have an EpiPen. Nothing like this has ever happened before.”

Elena sat on the bed, gasping. Her arms were covered in red blotches. She was beginning to feel light-headed and vertiginous, as if she was perpetually toppling over, even though she could see that she was perfectly still.

“ETA fifteen minutes,” Daniel told her.

Elena nodded. At least they weren’t saying two hours. “I just need . . .” he added, before deciding not to waste time explaining. He dashed out of the room, and returned half a minute later with a short length of plastic tubing and a bottle of olive oil. Elena didn’t know whether she should feel reassured or terrified that the operator was contemplating talking him through an emergency intubation, but better that than skewering her windpipe with the shell of a ballpoint pen.

“If it was the mushrooms, why am I okay?” Daniel fretted. Elena was sure that the restaurant’s supplier kept a tight control on their product; it wasn’t as if they foraged in the wild and might have misidentified the species. The sour cream in the Stroganoff might have been spoiled, but her symptoms seemed too extreme for an ordinary bout of food poisoning. Maybe the meal had nothing to do with it.

Daniel held her hand. Her nose was running now, her nostrils burning, like hay fever on . . . well, not steroids, that would have had the opposite effect. Elena let her eyes close fully and curled her swollen tongue against her stinging palate, trying to find a configuration that let the most air through while still keeping her from choking on the mucus sliding down the back of her throat.

The pounding on the door came sooner than she’d expected. Daniel ran to let the paramedics in. Elena opened her eyes as widely as she could as the woman examined her, questioned her—eliciting no comprehensible replies—questioned Daniel, then jabbed her in the thigh.

Elena felt a jolt of clarity, as if she’d been wrenched out of a mud pit into open air. It took a little longer for her breathing to become normal, but in a matter of minutes all the worst symptoms had abated.

“We’re going to need to take you in to the emergency room,” the paramedic who’d injected her explained.

“But I’m fine now,” Elena insisted.

“Maybe, but if you don’t know what brought this on, you need to be checked out.”

At the hospital, they waited three hours before anyone could see her. Dr. Eggar took a detailed history—mostly asking questions to which the answer was “no”—then ordered some blood tests and went away.

“You should go home and get some sleep,” Elena told Daniel.

He laughed and shook his head. “I’m not leaving until they discharge you.”

“What if they can’t tell us what caused it?”

He said, “Then you must have swallowed some mysterious allergen that blew in on the wind . . . but even if they can’t name it, we can re-wash all the plates and cutlery and hope it was a freakish accident that’s never going to happen again.”

Dr. Eggar returned just before noon. “I think we know the problem,” she said. “You’re reacting to a molecule called alpha-Gal, which is found on the cells of most mammals—including cows, pigs, and sheep. You’ve developed a sensitivity to it, and that makes you allergic to red meat.”

Elena had heard of Alpha-Gal Syndrome, but she’d always thought of it as a rare condition, mostly confined to the countryside, and it had never even crossed her mind that her own body might be rebelling against anything as benign and familiar as meat.

“So I must have been bitten by a tick?” she asked. But when? Between the lamb curry she’d had three days earlier, and the beef Stroganoff that Daniel had brought home from the restaurant that night?

“That would explain it,” Dr. Eggar confirmed. “We used to think the tick needed to have fed on an animal with alpha-Gal in order to get it into its saliva, but it turns out the ticks make their own, and some bacteria that live in ticks make it, too. So even a tick whose previous hosts were birds, which don’t have alpha-Gal, can give you the allergy.”

Daniel had been listening intently, trying to follow all the repercussions. “So even if she was bitten by a tick that came from a bird, she can still eat chicken?”

Dr. Eggar said, “Sure. Birds and fish are fine.” She turned back to Elena. “Even dairy products should be okay, but I’d tread carefully for a while. I’ll give you an information booklet, and some antihistamine tablets and EpiPens in case you eat the wrong thing by accident—additives like gelatin aren’t always labeled clearly. There’s also a risk of a more severe reaction to any subsequent tick bite, so you’ll want to avoid that. But it’s all spelled out in the pamphlet.”

She left to arrange Elena’s discharge.

Daniel said, “At least you got a clear diagnosis. And it shouldn’t be that hard to work around it.”

“I’m still trying to figure out how I could have been bitten,” Elena mused. “I don’t think I’ve touched a dog or a cat in months, or walked through long grass. Though maybe someone at work who has pets brought ticks into the building.”

“Ticks in an entomology lab?” Daniel joked. “What an outrage.”

“You mean because they’re arachnids, not insects?”

“I didn’t know that,” he admitted. “But the university really should defend these taxonomic boundaries.”

“Don’t worry, our wasps can look after themselves.”

At home, Elena promised to rest, and Daniel reluctantly left for the restaurant. She still felt lethargic, but she wasn’t too tired to start searching through the literature on the syndrome. Along the east coast of Australia, the supposed culprit was the “paralysis tick,” Ixodes holocyclus, which needed three successive blood meals, one for each stage of its life cycle: larva, nymph, and adult. The adults started out four millimeters long and ballooned to the size of a thumbnail when engorged, so it was hard to believe she could have missed that—while the neurotoxin that gave them their common name was powerful enough to kill a dog. But the larvae were tiny, and could often feed without provoking any immediate reaction, so perhaps that was what had happened to her. Hikers and forestry workers were at far higher risk than city dwellers, but maybe she’d stooped down on a patch of grass, for a second or two, to pick up something she’d dropped.

Ticks aside, alpha-Gal had its own fascinating natural history. Though present in all other mammals, it had disappeared from Old World primates some twenty-eight million years ago, possibly as a response to a pathogen that contained the same molecule, and which could be better fought if antibodies against it were no longer screened out for their autoimmune activity. Now the microbiota in every healthy human gut churned out alpha-Gal, and in response, the healthy human immune system contained more antibodies targeting it than anything else. But those were IgG antibodies; Alpha-Gal Syndrome, like all allergies, arose from a different kind, IgE. Exactly why the alpha-Gal in tick saliva primed the body for an IgE response, and the alpha-Gal that entered the bloodstream after eating meat triggered it, seemed to be due to how the structure was presented; it could end up bound to different carbohydrates and proteins in different circumstances, and that affected the immune system’s response. None of this was entirely settled, though; an alternative theory raised the possibility that a prostaglandin in tick saliva was able to cause immunoglobulin “class switching,” where some of the B cells that had hitherto cranked out anti-alpha-Gal IgG changed to IgE.

Elena put her phone down and closed her eyes. Whatever the biochemical fine print, the upshot was the same. She was grateful she’d survived the anaphylaxis, but it was hard not to mourn what she’d lost. There were memories, now, that she might never have the chance to summon up the same way again: her grandmother’s lamb ragu with gnocchi, her mother’s pork tenderloin with sun-dried tomatoes, all the sumptuous meals Daniel had cooked for her since they’d met. The condition could abate after several years, especially if she managed to avoid any further tick bites, but since she’d hardly been reckless in the first place, it was difficult to see what precautions she was supposed to take.

She dozed off, then woke to the sound of Daniel in the kitchen. She went out to greet him.

“You’re home early,” she said.

“That’s one of the perks of hiring good staff,” he replied. “They don’t need me breathing down their necks all the time.”

“What are you making?” Elena had been ready to protest that she still had no appetite, but in fact the smell of garlic and spices had already set her mouth watering.

“A Moroccan stew, with eggplant and chickpeas.”

“So no meat at all?”

Daniel turned from the stove to face her. “Do you mind? I thought you’d get sick of chicken and fish pretty fast if you never had anything else, so . . .”

“No, it sounds delicious.”

When they sat down to eat, the promise of the aromas was more than fulfilled, and Elena savored every mouthful. A few hours ago, she’d been grieving for a handful of ingredients she could no longer consume, but that seemed absurd now.

“I can’t believe you never made this at home before,” she told Daniel.

He smiled. “You never asked me to. You know . . . we could eat something different every night for the rest of our lives, if you want.”

Elena wasn’t sure how seriously he meant that—and she had no intention of holding him to it—but it was a beautiful thought. When it came to food, human imagination and ingenuity were boundless. Even as one set of possibilities slipped away from her, there’d always be something new to look forward to.