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

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СКАЧАТЬ sugar lump, and perhaps more clearly, the melodramatic queues outside the dinner hall as we waited with our school friends for a teenage booster shot. For many children and teenagers growing up now, the burden of history is even lighter, as not only the diseases themselves, but once-routine vaccinations, such as the dreaded ‘BCG’ for tuberculosis, are no longer necessary.

      Medical innovations and public health measures – largely those of the late nineteenth and early twentieth centuries – have made a profound difference to life as a human. Four developments in particular have taken us from a two-generation society to a four-, or even five-generation society in just one, long, lifetime. The first and earliest of these, courtesy of Edward Jenner and a cow named Blossom, is, of course, vaccination. Jenner knew that milkmaids were protected from developing smallpox by virtue of having been infected by the much milder cowpox. He thought it possible that the pus from a milkmaid’s pustules might, if injected into another person, transfer that protection. His first guinea pig was an eight-year-old boy named James Phipps – the son of Jenner’s gardener. Having inoculated Phipps, Jenner went on to attempt to infect the brave lad, twice injecting pus from a true smallpox infection. The young boy was utterly immune.

      Beginning with smallpox in 1796, and progressing to rabies, typhoid, cholera and plague in the nineteenth century, and dozens of other infectious diseases since 1900, vaccination has not only protected millions from suffering and death, but has even led to countrywide elimination or complete global eradication of some pathogens. Thanks to vaccination, we no longer have to rely solely on our immune systems’ experiences of full-blown disease to defend us against pathogens. Instead of acquiring natural defences against diseases, we have circumvented this process using our intellect to provide the immune system with forewarning of what it might encounter.

      Without vaccination, the invasion of a new pathogen prompts sickness and possibly death. The immune system, as well as tackling the invading microbe, produces molecules called antibodies. If the person survives, these antibodies form a specialist team of spies that patrol the body looking out specifically for that microbe. They linger long after the disease has been conquered, primed to let the immune system know the moment there is a reinvasion of the same pathogen. The next time it is encountered, the immune system is ready, and the disease can be prevented from taking hold.

      Vaccination mimics this natural process, teaching the immune system to recognise a particular pathogen. Instead of suffering the disease to achieve immunity, now we suffer only the injection, or oral administration, of a killed, weakened or partial version of the pathogen. We are spared illness but our immune systems still respond to the introduction of the vaccine, and produce antibodies that help the body to resist disease if the same pathogen invades for real.

      Society-wide vaccination programmes are designed to bring about ‘herd immunity’ by vaccinating a large enough proportion of the population that contagious diseases cannot continue their spread. They have meant that many infectious diseases are almost completely eliminated in developed countries, and one, smallpox, has been totally eradicated. Smallpox eradication, as well as dropping the incidence of the disease from 50 million cases a year worldwide to absolutely none in little more than a decade, has saved governments billions in both the direct cost of vaccination and medical care, and the indirect societal costs of illness. The United States, which contributed a disproportionately large amount of money to the global eradication effort, recoups its investment every twenty-six days in unspent costs. Governmental vaccination schemes for a dozen or so other infectious diseases have dramatically reduced the number of cases, reducing suffering and saving lives and money.

      Today, most countries in the developed world run vaccination programmes against ten or so infectious diseases, and half a dozen are marked for regionwide elimination or global eradication by the World Health Organisation. These programmes have had a dramatic effect on the incidence of these diseases. Before the worldwide eradication programme for polio began in 1988, the virus affected 350,000 people a year. In 2012, the disease was confined to just 223 cases in only three countries. In just twenty-five years, around half a million deaths have been prevented and 10 million children who would have been paralysed are free to walk and run. Likewise for measles and rubella: in a single decade, vaccination of these once-common diseases has prevented 10 million deaths worldwide. In the United States, as in most of the developed world, the incidence of nine major childhood diseases has been reduced by 99 per cent by vaccination. In developed countries, for every 1,000 babies born alive in 1950, around forty would die before their first birthday. By 2005, that figure had been reduced by an order of magnitude, to about four. Vaccination is so successful that only the oldest members of Western society can remember the horrendous fear and pain of these deadly diseases. Now, we are free.

      After the development of the earliest vaccines came a second major health innovation: hygienic medical practice. Hospital hygiene is something we are still under pressure to improve today, but in comparison with the standards of the late nineteenth century, modern hospitals are temples of cleanliness. Imagine, instead, wards crammed full with the sick and dying, wounds left open and rotting, and doctors’ coats covered in the blood and gore of years of surgeries. There was little point in cleaning – infections were thought to be the result of ‘bad air’, or miasma, not germs. This toxic mist was thought to rise from decomposing matter or filthy water – an intangible force beyond the control of doctors and nurses. Microbes had been discovered 150 years previously, but the connection had not been made between them and disease. It was believed that miasma could not be transferred by physical contact, so infections were spread by the very people charged with curing them. Hospitals were a new invention, born of a drive towards public health care and a desire to bring ‘modern’ medicine to the masses. Despite the good intentions, they were filthy incubators for disease, and those attending them risked their lives for the treatment they needed.

      Women suffered most as a result of the proliferation of hospitals, as the risks of labour and giving birth, rather than falling, actually rose. By the 1840s, up to 32 per cent of women giving birth in hospital would subsequently die. Doctors – all male at that time – blamed their deaths on anything from emotional trauma to uncleanliness of the bowel. The true cause of this horrifyingly high death rate would at last be unravelled by a young Hungarian obstetrician by the name of Ignaz Semmelweis.

      At the hospital where Semmelweis worked, the Vienna General, women in labour were admitted on alternate days into two different clinics. One was run by doctors, and the other by midwives. Every second day, as Semmelweis walked to work, he’d see women giving birth on the street outside the hospital doors. On those days, it was the turn of the clinic run by doctors to admit labouring women. But the women knew the odds for their survival would not be good if they could not hold on until the following day. Childbed fever – the cause of most of the deaths – lurked in the doctors’ clinic. So they waited, cold and in pain, in the hope that their baby would delay its entrance to the world until after midnight had struck.

      Getting admitted to the midwife-run clinic was, relatively speaking, a far safer proposition. Between 2 and 8 per cent of new mothers would die of childbed fever in the care of midwives – far fewer than succumbed in the doctors’ clinic.

      Despite his junior status, Semmelweis began to look for differences between the two clinics that might explain the death rates. He thought overcrowding and the climate of the ward might be to blame, but found no evidence of any difference. Then, in 1847, a close friend and fellow doctor, Jakob Kolletschka, died after being accidentally cut by a student’s scalpel during an autopsy. The cause of death: childbed fever.

      After Kolletschka’s death, Semmelweis had a realisation. It was the doctors who were spreading death among the women in their ward. Midwives, on the other hand, were not to blame. And he knew why. Whilst their patients laboured, the doctors would pass the time in the morgue, teaching medical students using human cadavers. Somehow, he thought, they were carrying death from the autopsy room to the maternity ward. The midwives never touched a corpse, and the patients dying on their ward were probably those whose post-natal bleeding meant a visit from the doctor.

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