31 May 2023 Cats, peanuts, bee stings… the irritating truth about allergies

More and more of us suffer from allergies, and medicine is struggling to keep up. Medical anthropologist, Theresa MacPhail, has been searching for answers….

When Theresa MacPhail was four, her brother was killed in an accident. When she was 14, her mother died in a car crash. And when she was 24, her father died from anaphylactic shock after a bee flew in through the open window of his truck and stung him in the neck.

For anyone else, these devastating experiences would almost certainly have been psychologically catastrophic. Instead, MacPhail decided to use what she’d been through as the bedrock for her PhD at UC Berkeley, and then her career as a medical anthropologist.

She laughs. “I’m like the doyenne of death. I have been thinking my whole life about the things that make people ill and pass away, because of my history. These are the waters I’ve been in since I was a kid. Rather than ignoring it, I decided to go at all my fears and insecurities about mortality. And then I basically made it my profession.”

Much of MacPhail’s anthropological research has been into our collective fear of viruses, but six years ago and in her late 40s, repeated chest infections led to her unexpectedly being diagnosed with respiratory allergies.

“When you’re 24, you think you’re invincible, so the only time I thought about whether I had the same allergy as my dad was when a bee came near me. But after I was diagnosed, I told all my friends about trying to figure out what I’m allergic to, and it turns out everyone has an allergy story. And then I thought, ‘Wait, just how prevalent are allergies?’

I had questions about whether this is just happening to us now, or was it the same in the past? I found academic articles but nothing accessible. I was complaining to a friend who is also a medical anthropologist. And that conversation is now famous in my mind, because he said to me, ‘Hey, aren’t you a researcher?’”

The result is a brilliantly comprehensive and highly readable book, Allergic: How Our Immune System Reacts to a Changing World, five years in the making and the first ever to track both the history of allergies and the state of modern allergy science, while also trying to get to the bottom of how, almost 30 years ago, her father came to be unknowingly and fatally allergic to bee venom, and whether she might be, too.

If that sounds outrageously complicated, it was. “Every allergist I interviewed told me it couldn’t be done. They were all like, ‘What are you trying to do? And I said, ‘I’m trying to do the whole story.’ And they said, ‘All allergies?’ And I said, ‘Yeah’, and they said, ‘Good luck.’”

It’s startling that this is the first popular science book of its sort. “Culturally, people have self-trained that allergies are not a big deal. But allergies are a signal that your immune system isn’t happy with the world you live in. And I think that’s a conversation we should all be having.”

Despite interviewing practically every top allergist and allergy researcher in the world and being comprehensively tested, it is very unlikely MacPhail will ever know exactly what she is allergic to, unless she is unlucky enough to have an extreme and therefore very obvious reaction. Her experience mirrors that of many allergy sufferers……

Anecdotal evidence has long suggested that our allergy problem is getting worse, but until recently it’s been hard to be sure

We are better at diagnosing allergies than we were two centuries ago, say, and the theory has always been that back then, people were more worried about tuberculosis or any of the myriad other things which could kill you or your children in the pre-antibiotic and antiseptic age. A runny nose, itchy rash or upset stomach would barely register, meaning that while fatal reactions to bites and stings certainly happened, if respiratory, dermatological or food allergies did exist, no one took much notice.

MacPhail, however, has gathered a raft of data which conclusively shows that yes, we are becoming more allergic. There’s the study by the Food Allergy and Anaphylaxis Network showing that peanut allergy now runs at 1 in every 70 kids, versus 1 in 250 in 1997. In the US, on average, someone now arrives in A&E every two hours with a severe allergic reaction. A study by Imperial College London suggests food allergy anaphylaxis increased by 5.7% between 1998 and 2018. US hospital admissions for asthma tripled between 1970 and 1990, and asthma rates continue to climb in developing countries.

I asked every expert, what is the cause? They simply said everything, it’s everything we’re doing.

MacPhail’s conservative estimate, after wading through global datasets of highly variable quality, is that 10% of the world’s population – 800 million people – will have a respiratory allergy at some point in their lives. But she says it’s impossible to know exactly how many people have other allergies, because there is so much variation in how a person is diagnosed, if at all.

Allergy UK says one in three Britons will experience an allergy during their lifetime and that currently 50% of British children have an allergy. Research by the European Academy of Allergy and Clinical Immunology suggests that up to half of Europeans may be affected by allergy by 2025. We may not have precise numbers, but it’s clear that allergies are a big problem, getting bigger.

Another problem with the data – which often relies on self-reporting – is the public’s misunderstanding of the difference between intolerances and allergies. “Most of us do not understand what the results of a scratch test show,” says MacPhail, of the tests done by breaking the skin and applying a tiny amount of possible allergens, then waiting to see if a skin reaction occurs. “They’re just telling you if you have a sensitivity. The difference between sensitivity, intolerance and allergy is the number one thing all allergists wish we could understand.”….

So why are we getting more allergic?

“No one knows what the smoking gun is. It’s multifactorial.” she says. “That’s quite overwhelming and to think about what the solution would be is overwhelming, too. I asked every expert: ‘What is the cause?’ All of them refused to answer and simply said ‘Everything’. It’s everything we’re doing.'”

There are many things which MacPhail’s exhaustive research shows are part of the allergenic picture. The mass movement of people to cities during industrialisation, cutting our access to daylight, animals, dirt and native plants (the UK industrialised first and fastest, which may explain why we are in the global top three countries for allergies).

More of us live in housing which is warmer, damper, mouldier and fuller of upholstery-loving dust mites. Children playing outdoors less in the first three years of life. Vitamin D deficiency due to a shift to a desk-based economy.

Using bacteria-killing, lung-irritating cleaning products. Antibacterial wipes. Genetics. Hormones. Using dishwashers, which remove all traces of potentially protective bacteria from our crockery. Antibiotics. Increasing C-section births and decreasing rates of breastfeeding, both of which seem to impact the newborn microbiome and are associated with higher rates of allergy.

Climate change causing higher levels of pollen. Air pollution. The use of proton pump inhibitors like Nexium for digestive issues. Even garden cities and our increased focus on greening urban areas might be increasing nasal allergies.

Fundamentally, what Allergic shows is that our immune systems haven’t adapted to the modern world at all. “Several clinicians told me that if we could run an experiment where everyone lives the way they lived in 1600, allergies would drop; but, of course, none of us are going to do that,” she says.

Fascinatingly, MacPhail also notes that companion animals like cats and dogs are also becoming more allergic, but that there is no sign of the same thing happening to wild animals, which points to a big part of the puzzle being inside our homes.

“We all want there to be one answer. And then we can just all stop doing X, whatever X is, and the problem of allergy goes away. That’s not how it works – it’s way too complex and highlights how little we know about basic immune mechanisms.”

MacPhail would love to see more money going towards a better understanding of allergies and the immune system, rather than applied research looking for drug treatments which just tweak dials within the immune system, and which have side effects…..

The Guardian: Read the full article here