It’s allergy season once again. If you’re one of the 81 million Americans with hay fever, spring is a mixed blessing. Yes, the days are longer, but they are accompanied by itchy eyes, a runny nose, and an endless search for antihistamines. On days when pollen counts are highest, seasonal allergies are like an assault, from the outside world, but also from our own body’s own immune system going into overdrive.
There is also a growing number of allergy sufferers. In 1997, about 0.4 percent of American children were reported to have a peanut allergy. By 2008, the figure was 1.4 percent. In the UK, hospital admissions due to severe food allergies tripled between 1998 and 2018. And while rates of asthma, often triggered by allergies, have leveled off in the US, they continue to rise globally thanks to the rising rates in the developing world. We’re also seeing an increase in unusual allergies, such as alpha-gal syndrome, in which some people bitten by lone star ticks develop strong reactions to red meat.
Watching the rise in allergies, it’s hard to shake the feeling that something is off. Either it’s the outside world, our bodies, or the complex interaction between the two, but something is wrong. The question is why and what can we do about it.
A good place to start is to find out what the heck allergies really are. in his book Allergy: how our immune system reacts to a changing world, medical anthropologist Theresa MacPhail attempts to do just that. One theory is that allergic reactions evolved as a way for the body to expel carcinogens and toxins, from insect stings to snake bites. Even a few centuries ago, an extreme immune response to a potentially fatal snakebite could have been a useful way for the body to respond, a researcher tells MacPhail.
As the world has changed, our overactive immune systems have begun to seem decidedly out of step with the threats we face. It doesn’t help that growing seasons for crops are getting longer, exposing people to pollen earlier each spring. At the same time, changes in diets and lifestyles are altering our microbiomes, perhaps making children more prone to sensitization to food allergens. Stress could also influence our susceptibility to allergies: we know that stress hormones elicit a similar type of response in mouse cells as allergic stressors.
If this sounds a bit inconclusive, then you’d be right. As MacPhail discovers, it’s hard to pin down exactly what’s causing the rise in allergies: Doctors don’t even fully agree on what an allergy is. is or the best way to diagnose one. But MacPhail has good reason to dive into these complexities. In August 1996, his father was driving down a New Hampshire highway on her way to a beach with his girlfriend. A lone bee flew through the sedan’s open window and stung him on the side of the neck. Shortly after, his father died of anaphylactic shock; he was 47 years old. “You’re really here today because you want to know why your father died,” an allergy doctor tells MacPhail during an interview.
