10% Human: How Your Body’s Microbes Hold the Key to Health and Happiness. Alanna Collen

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СКАЧАТЬ being injected with a tiny quantity of penicillin, the policeman’s fever dropped, and he began to recover. The miracle was not to be, however. A few days into his treatment, penicillin supplies ran out. Florey had attempted to extract any remaining penicillin from the constable’s urine to continue the treatment, but on the fifth day, the policeman died. It is unthinkable now to die from a scratch or an abscess, and we often take antibiotics without heed to their life-saving properties. Surgery, too, would carry enormous risk were it not for the protective shield of intravenous antibiotics given before the first cut is made.

      Our twenty-first-century lives are a kind of sterile ceasefire, with infections held at bay through vaccinations, antibiotics, water sanitation and hygienic medical practice. We are no longer threatened by acute and dangerous bouts of infectious disease. Instead, the past sixty years have seen a collection of previously rare conditions rise to prominence. These chronic ‘twenty-first-century illnesses’ have become so common that we accept them as a normal part of being human. But what if they are not ‘normal’?

      Looking around among your friends and family, you won’t see smallpox, measles or polio any more. You might think how lucky we are; how healthy we are these days. But look again and you might see things differently. You might see the sneezing and red, itchy eyes of your daughter’s hay fever in the spring. You might think of your sister-in-law, who has to inject herself with insulin several times a day because of her type 1 diabetes. You might be worried your wife will end up in a wheelchair with multiple sclerosis as her aunt did. You might have heard about your dentist’s little boy who screams, and rocks himself, and won’t make eye contact, now that he has autism. You might get impatient with your mother who is too anxious to do the shopping. You might be searching for a washing powder that doesn’t make your son’s eczema worse. Your cousin might be the awkward one at dinner who can’t eat wheat because it gives her diarrhoea. Your neighbour might have slipped unconscious whilst searching for his EpiPen after accidentally eating nuts. And you might have lost the battle to keep your weight where beauty magazines, and your doctor, say it should be. These conditions – allergies, autoimmune diseases, digestive troubles, mental health problems and obesity – are the new normal.

      Let’s take allergies. Perhaps there’s nothing alarming about your daughter’s hay fever, as 20 per cent of her friends also snuffle and sneeze their way through summer. You are not surprised by your son’s eczema, because one in five of his classmates have it too. Your neighbour’s anaphylactic attack, terrifying though it was, is common enough that all packaged foods carry warnings if they ‘may contain nuts’. But have you ever asked yourself why one in five of your children’s friends have to take an inhaler to school in case they suffer an asthma attack? Being able to breathe is fundamental to life, yet without medication, millions of children would find themselves gasping for breath. What about why one in fifteen children are allergic to at least one type of food? Can that be normal?

      Allergies affect nearly half of us in developed countries. We dutifully take our antihistamines, avoid picking up the cat, and check the ingredients lists of everything we buy. We unthinkingly do what is necessary to stop our immune systems overreacting to the most ubiquitous and innocuous of substances: pollen, dust, pet hair, milk, eggs, nuts, and so on. These substances are being treated by the body as if they are germs that need to be attacked and removed. It hasn’t always been this way. In the 1930s, asthma was rare, affecting perhaps one child in every school. By the 1980s, it had shot up, and one child in every class was affected. In the last decade or so, the rise has levelled off, but it has left a quarter of children with asthma. The same goes for other allergies: peanut allergies, for instance, trebled in just ten years at the end of the last century, and then doubled again in the next five years. Now we have nut-free zones in schools and workplaces. Eczema and hay fever too were once rare and are now a fact of life.

      This is not normal.

      What about autoimmune diseases? Your sister-in-law’s insulin habit is common enough, with type 1 diabetes affecting, as it does, about 4 in every 1,000 people. Most people have heard of the multiple sclerosis (or MS) that’s destroyed your wife’s aunt’s nerves. And then there’s rheumatoid arthritis wrecking joints, coeliac disease attacking the gut, myositis shredding muscle fibres, lupus pulling apart cells at their core, and about eighty other such conditions. As with allergies, the immune system has gone rogue, attacking not just the germs that bring disease, but the body’s own cells. You might be surprised to learn that among them, autoimmune diseases affect nearly 10 per cent of the population in the developed world.

      Type 1 diabetes (T1D) makes for a great example, because it is an unmistakable condition, so records are relatively reliable. ‘Type 1’ is the version of diabetes that usually strikes early, often in the teenage years, attacking the cells of the pancreas, and completely preventing the production of the hormone insulin. (In type 2 diabetes, insulin is produced, but the body has grown less sensitive to it, so it doesn’t work as well.) Without insulin, any glucose in the blood – whether that’s from the simple sugars in sweets and desserts or from the carbohydrates in pasta and bread – cannot be converted and stored. It builds up and quickly becomes toxic, bringing with it a raging thirst and constant need to urinate for the unfortunate teenager. The patient wastes away, and weeks or months later, death follows, often from kidney failure. That is, unless insulin is injected. Pretty serious, then.

      Fortunately, compared to most conditions, it’s straightforward to diagnose, and always has been. These days, a quick check of the amount of glucose in the blood after fasting usually gives it away, but even 100 years ago diabetes could be detected by a willing doctor. I say willing, because the test for it involved tasting the patient’s urine. A sweetness within the tang indicated that there was so much glucose in the blood that it had been forced out into the urine by the kidneys. Though undoubtedly more cases were missed in the past than now, and many would have gone unrecorded, our understanding of the prevalence of type 1 diabetes over time is a reliable indicator of the changing status of autoimmune diseases.

      About 1 in 250 people in the West are stuck playing the role of their own pancreas, calculating how much insulin they need and then injecting it, to store away the glucose they have consumed. What’s extraordinary is that this high prevalence is new: type 1 diabetes was almost non-existent in the nineteenth century. Hospital records for Massachusetts General Hospital in the US, kept over seventy-five years until 1898, log only twenty-one cases of diabetes diagnosed in childhood, out of nearly 500,000 patients. It’s not a case of missed diagnosis, either – that urine-taste test, the rapid weight loss and the inevitable fatal outcome made the disease easy to recognise even back then.

      Once formal records had been set up just before the Second World War, the prevalence of type 1 diabetes could be tracked. Around 1 or 2 children in every 5,000 were affected in the US, UK and Scandinavia. The war itself altered nothing, but not long afterwards, something changed, and cases began to rise. By 1973, diabetes was six or seven times as common as it had been in the Thirties. In the Eighties, the rise levelled off at its current figure of about 1 in 250.

      The rise in diabetes is matched by rises in other autoimmune conditions. Multiple sclerosis destroyed the nervous systems of twice as many people at the turn of the millennium as it did two decades previously. Coeliac disease, in which the presence of wheat prompts the body to attack the cells of the intestine, is a startling thirty or forty times as common now as it was in the 1950s. Lupus, inflammatory bowel disease and rheumatoid arthritis too have been on the rise.

      This is not normal.

      What about our collective battle with excess weight? Odds are I’m right in my flippant assumption that you struggle with your weight, as well over half of us in the Western world are either overweight or obese. It’s astonishing to think that being a healthy weight puts you in the minority now. Being fat is so typical that old shop mannequins have been replaced by larger versions, and television shows turn weight loss into a game. These changes are perhaps to be expected: statistically speaking, being overweight is the reality for most people.

      But СКАЧАТЬ