Our Irritated Bodies in a Changing World

About the Book

An “important and deeply researched” (The Wall Street Journal) exploration of allergies, from their first medical description in 1819 to the cutting-edge science that is illuminating the changes in our environment and lifestyles that are making so many of us sick

Hay fever. Peanut allergies. Eczema. Either you have an allergy or you know someone who does. Billions of people worldwide—an estimated 30 to 40 percent of the global population—have some form of allergy. Even more concerning, over the last decade the number of people diagnosed with an allergy has been steadily increasing, placing an ever-growing medical burden on individuals, families, communities, and healthcare systems.

Medical anthropologist Theresa MacPhail, herself an allergy sufferer whose father died of a beesting, set out to understand why. In pursuit of answers, MacPhail studied the dangerous experiments of early immunologists as well as the mind-bending recent development of biologics and immunotherapies that are giving the most severely impacted patients hope. She scaled a roof with an air-quality controller who diligently counts pollen by hand for hours every day; met a mother who struggled to use WIC benefits for her daughter with severe food allergies; spoke with doctors at some of the finest allergy clinics in the world; and discussed the intersecting problems of climate change, pollution, and pollen with biologists who study seasonal respiratory allergies.

This is the story of allergies: what they are, why we have them, and what that might mean about the fate of humanity in a rapidly changing world.
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Praise for Allergic

“An important and deeply researched book by Theresa MacPhail, a medical anthropologist who memorably portrays the human face of disease . . . In Ms. MacPhail’s analysis, allergy is not only the evil twin of immunity, but also the unexpected dark side of material progress, which has made us unhealthy in ways that we struggle in vain to cure. The author doesn’t have an easy fix for the allergy crisis, but her compassionate insights into the problem make for engrossing reading.”The Wall Street Journal

Allergic is the definitive biography of allergies. This accessible, comprehensive, and troubling portrait should be read by those who suffer from allergies and those who care about them, which, as MacPhail so carefully documents, includes almost all of us.”—Michael Moss, bestselling author of Salt Sugar Fat and Hooked

“A fascinating account that most of us (sniffle sniffle) will find of compelling interest—and also a powerful reminder that what we do to the world around us eventually affects the world inside us.”—Bill McKibben, author, educator, and founder of Third Act

Allergic is just the sort of thoughtful, comprehensible, and comprehensive book we urgently need to understand how rapidly changing modern environments are interacting with our ancient immune systems to cause a frightening explosion in allergies.”—Daniel Lieberman, author of The Story of the Human Body and Exercised

“In this astute, empathetic, and wonderfully informative investigation, Theresa MacPhail makes a persuasive case that cooperation—with one another and with our internal ecosystems—is the key to allergy relief.”—Michelle Nijhuis, author of Beloved Beasts

“Comprehensively researched, deftly told, and radiating both intellect and passion, Allergic is essential reading for anyone interested in our bodies and our world. I am grateful to have this book to share with my allergy patients.”—Kari Nadeau, MD, PhD, director of the Sean N. Parker Center for Allergy and Asthma Research at Stanford University

“A holistic study of how allergies continue to bewilder medical science . . . While the culprits responsible for the increases in allergic sufferers are debatable moving targets, MacPhail skillfully narrows down the possibilities and some of the solutions. . . . [Her] examination of the science of immunology from a social and cultural perspective will give readers plenty of relevant, thought-provoking information. An exhaustive and accessible report.”Kirkus Reviews
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Chapter 1

What Allergy Is (and Isn’t)

Before I began researching this book, I had no idea just how massive the problem of allergy truly is. Approximately 40 percent of the entire human population already has some form of allergic condition. And by 2030, experts estimate that statistic will increase to 50 percent. But before we can dive more deeply into what these numbers might mean, and why allergies are projected to rise over the next few decades, we need to answer a more basic and fundamental question: What exactly is an allergy?

When I first started talking with scientists and allergists, I assumed I knew what an allergy was. If someone had quizzed me, I would have said, confidently, that an allergy was a negative bodily response to something a person had eaten, touched, or inhaled. If pressed for more details, I probably would have trotted out what I had learned long ago from an introductory biology course—that the human immune system is similar to a defense system. It reacts to foreign substances, such as viruses, bacteria, and parasites, and helps to protect us against infection. But in people with allergies, that same immune system is triggered by something in the environment—like pollen or milk or nickel in metal jewelry—that is harmless to nonallergic people. I would have listed sneezing, runny or stuffy nose, coughing, rashes, redness, hives, swelling, and difficulty breathing as possible symptoms.

Whenever I ask normal people (i.e., not scientists or biomedical experts) to explain what an allergy is, I usually hear something similar to my own initial definition. People of all ages and backgrounds tend to think of allergy and allergens as, as one young nonallergic man described them to me: “Some sort of imbalance with whatever is entering your system. It just doesn’t mesh well with whatever is in your body and it causes your body to try to get rid of it.” Another man described allergy as the body being “self-destructive” when it doesn’t know how to handle something like pollen or a particular food. In one memorable interview, a man with several allergies who had grown up in Chihuahua, Mexico, near the Texas border, suggested that his body is in a constant defense mode—but sees this as primarily positive. He thinks of himself as well defended and described his body as more “careful” and alert than the bodies of nonallergic people. These are all more or less accurate depictions of allergic-type immune responses and they work well enough . . . until they don’t.

Even people who have allergies don’t always understand what, in exact terms, they are or how to distinguish them from nonallergic conditions with similar symptoms.

Take “Chrissie,” for example, one of the first allergy patients interviewed for this book. By the time we spoke, Chrissie had been coping with respiratory allergy symptoms, hives, sporadic swelling of her eyes, and frequent stomach issues for years. She had been diagnosed with hay fever, or seasonal allergic rhinoconjunctivitis, and occasionally visited an ear, nose, and throat specialist (ENT) for treatment when her symptoms changed or worsened. She also experienced gastrointestinal symptoms and skin rashes if she accidentally consumed milk or gluten. Years ago, Chrissie went to see an allergist and was tested for reactions to the most common allergens. Her skin was completely nonreactive to all food allergens, and the allergist told her that it was extremely unlikely that the symptoms she experienced were due to a food allergy. Chrissie’s ENT has repeatedly encouraged her to get retested, but she hasn’t; instead, she goes online to research her symptoms and crowdsource possible remedies.

When asked to define what an allergy is, Chrissie said that it is what happens when the body can’t handle something, especially if the body has come into contact with something too often or in too great of a quantity. Over time and with repeated exposure, she explained, the body ceases to be able to process those things, giving rise to symptoms like her own. She doesn’t believe the results of her skin tests for food allergens and insists that she has a food allergy; since wheat and milk are ingredients in most foods, she posits that her body has learned to reject them over decades of consuming them.

I am beginning this chapter with Chrissie’s story—her misconception of what an allergy is and isn’t, and her palpable confusion and frustration—to illustrate what we typically get right about allergy as well as what we typically get wrong. When it comes to her respiratory allergies, Chrissie is correct in thinking that her body is responding to something that it has had repeated exposure to, but she is wrong about her body being unable to process pollen. (As we’ll soon see, it’s more that her body isn’t able to tolerate it or ignore it.) Chrissie likely doesn’t have a true food allergy, despite having very real symptoms, because she doesn’t show any sensitization to milk or gluten (as evidenced by the results of her skin-prick test). In other words, her immune system is likely not reacting to the foods she’s ingesting. Her immune system is reacting to pollen, however, which causes her hay fever. What Chrissie is really confused about, then, is the difference between an intolerance (in this case, to certain foods, possibly caused by another condition like irritable bowel syndrome or a lack of the enzyme lactase that aids in breaking down the lactose in milk products) and an allergic response (to airborne allergens). And who could blame her? Even as a medical anthropologist with a decent understanding of immunology, I had to discover some of these distinctions the hard way.

The deeper I waded into the scientific literature on allergy and the more conversations I had with allergists and immunologists, the murkier the definitional waters got. To my initial surprise and frustration, the more I learned about how the intricacies of our immune system function, the harder, and not easier, it was to understand allergy. It turns out that what we commonly refer to as “allergy” is actually a grab bag of various conditions. The one thing they all have in common is this: They all involve a hypersensitive immune system reaction to an otherwise innocuous substance—an allergen—that doesn’t typically produce any immune response in nonallergic people. The symptoms of an allergy vary depending on how the allergen enters the body (via the skin, airway, or intestinal tract), the individual genetics of the person, and the many different “allergic pathways” the allergen can trigger.

So, then, what is an allergy? It’s a harmful immune-mediated hypersensitivity reaction to a harmless antigen, which is defined as any toxin or foreign substance that activates an immune response. That’s the technical scientific definition, but it likely doesn’t mean much to you—yet. To fully comprehend what an allergy is, we have to understand how the definition of the term itself shifted and changed over the past century. The concept of allergy is just over a century old, born out of early studies of the function of the mammalian immune system.

In the end, and as you’ll soon see, I learned that an allergy is perhaps best defined by what biological processes it sets in motion.

About the Author

Theresa MacPhail
Dr. Theresa MacPhail is a medical anthropologist, former journalist, and associate professor of science and technology studies who researches and writes about global health, biomedicine, and disease. She holds PhDs from the University of California, Berkeley and the University of California, San Francisco.
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