It’s an allergy season again. If you’re one of the 81 million Americans who suffer from hay fever, spring is a mixed blessing. Yes, the days are longer, but with them come itchy eyes, runny noses, and an endless hunt for antihistamines. On days when the pollen count is highest, seasonal allergies are like an assault – from the outside world, but also from our own body’s immune system which is going into overdrive.
There is also a growing number of people with allergies. In 1997, about 0.4% of American children had a peanut allergy. In 2008, the figure was 1.4%. In the UK, hospital admissions due to severe food allergies tripled between 1998 and 2018. And although rates of asthma, often triggered by allergies, have leveled off in the US, they continue to rise. rise globally through rising rates in developing countries. We are also seeing an increase in unusual allergies, such as alpha-gal syndrome, where some people bitten by lone ticks develop strong reactions to red meat.
Faced with the increase in allergies, it is difficult to get rid of the feeling that something is wrong. Either it’s the outside world, our bodies, or the complex interplay 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 allergies really are. In his book Allergic: how our immune system reacts to a changing world, medical anthropologist Theresa MacPhail is trying to do just that. One theory is that allergic reactions evolved as the body’s way of expelling carcinogens and toxins, from insect stings to snakebites. Even centuries ago, an extreme immune response to a life-threatening snakebite could have been a helpful way for the body to react, a researcher told 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 crop growing seasons are getting longer, exposing people to pollen earlier each spring. At the same time, changing diets and lifestyles are disrupting our microbiomes, perhaps making children more susceptible 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 that sounds a bit inconclusive, then you’d be right. As MacPhail finds out, it’s hard to pinpoint exactly what’s causing the increase in allergies — doctors aren’t even in complete agreement on what an allergy is. East or the best way to diagnose one. But MacPhail has good reason to delve into these complexities. In August 1996, his father was driving down a New Hampshire road en route to a beach with his girlfriend. A lone bee flew through the open window of the sedan and stung him on the side of the neck. Shortly after, her 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 allergist told MacPhail in an interview.
