The rollout of antibiotics had a massive impact on infection—from wounds but also contagious conditions. Antibiotics can help treat or cure leprosy, the plague, cholera, typhus, syphilis, and gangrene. In the US, cases of syphilis, already falling thanks to wider acceptance of condoms after Allied militaries finally started issuing them during the Second World War, tumbled from 70 for every 100,000 people to 4 out of 100,000 over just the ten years after 1946. Antibiotic treatment not only cured victims but prevented their future partners and their partners from getting the disease. The reduced intercourse risk was one spur for the sexual revolution of the 1960s.31 And typhus, the disease that had sunk Napoleon’s Russia campaign, has been, with the widespread help of antibiotics, limited to mountainous pockets in Peru, North Africa, Ethiopia, and Russia itself.32
It wasn’t just new medicines; it was the tool of delivery. Some forms of penicillin and most vaccines needed syringes to inject them. And over the course of the first sixty years of the twentieth century, injection technology was also revolutionized. Handmade glass-and-metal syringes cost about $50 each in 1900. Machine technology was developed before the First World War that eventually brought the price down to around $10 a syringe by 1950. The development of mass-produced single-use plastic syringes in the 1950s reduced the price to 18 cents by 1960 and about 1.5 cents by 2000.33 The smallpox vaccine was eventually delivered with a simple bifurcated needle—two spikes of metal.
When syringes are expensive, they have to be re-used a lot. Between 1917 and 1919, a vaccination campaign in French Equatorial Africa used just six syringes to deliver 90,000 vaccinations against sleeping sickness.34 That significantly increased the risk that vaccination campaigns would be a source of infection themselves. Not that the problem has completely disappeared in the age of the disposable syringe: a 2014 study sponsored by the World Health Organization estimated that up to 1.7 million people were infected each year with hepatitis B virus, and 33,800 with HIV, through an unsafe injection.35 Nonetheless, global health has been transformed by cheap delivery mechanisms combined with cheap vaccines.
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The single most important victory against disease was the global eradication of smallpox. In 1801, Jenner had suggested that “the annihilation of… the most dreadful scourge of the human species” would be the final result of his invention,36 but it still took both time and luck. In 1966, the Nineteenth World Health Assembly called for intensified efforts to eradicate smallpox. In a rare case of Cold War cooperation, the USSR donated more than 140 million doses of the vaccine annually while the US provided more vaccines together with advisers and equipment to rapidly roll out elimination efforts across twenty West African countries. In three and a half years, the disease was gone from the region. And the new bifurcated needle made vaccination something that could be carried out by anyone after a couple of hours of training: dip the needle in the vaccine bottle and the right amount would be caught between the twin points.37
Nonetheless, Donald Henderson, a participant in the global effort, reports smallpox eradication “was achieved by the narrowest of margins.” Progress “wavered between success and disaster, often only to be decided by quixotic circumstance or extraordinary performances by field staff.”38 Because 100 percent global immunization was an implausible goal (even fifty years later, millions of children go without vaccines each year), the campaign relied on reaching sites of infection fast enough that (nearly) all those in the vicinity could be given a shot to stop the outbreak from spreading. Again and again, vaccine teams raced to remote sites and immunized enough people fast enough that smallpox was contained.
In India, even after the World Health Organization thought that all cases of smallpox had been eradicated, the monitoring still went on—and that monitoring operation shows the scale of the global effort to eradicate the disease. In one month, 668,332 villages were searched by 115,347 workers visiting more than 3 million households. The effort uncovered 41,485 cases of chickenpox, but not one of smallpox—and so India was declared smallpox-free.39
In 1977, Ali Maow Maalin, a hospital cook from Mogadishu in Somalia, was asked for directions to the hospital by a man with two sick children. Maalin jumped in the van and started giving directions. The father warned him: the children had smallpox. Maalin replied, “Don’t worry about that.” But he’d long been afraid of needles and had dodged vaccinators. “It looked like the shot hurt,” he said. As a result, Maalin caught the disease.
But unlike hundreds of millions of smallpox sufferers in the twentieth century alone—more than five times the number who died in World War Two—he survived. Even better, he was the last person to catch the disease outside of the lab (Janet Parker from the Birmingham lab release was the last to die; her mother had a mild case and recovered). Three years after Maalin was infected, the whole planet was declared smallpox-free. The scourge of the Old World for centuries, and a destroyer of the New World after Columbus, had been completely defeated.
Maalin went on to spend his life vaccinating others. When he met parents who refused to vaccinate their kids, he’d tell his story, Maalin said in 2006: “I tell them how important these vaccines are. I tell them not to do something foolish like me.”40
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In many ways smallpox was a comparatively simple disease to wipe out worldwide. There’s no animal reservoir of the infection (bats or birds, for example)—wipe it out in humans and it’s gone. Once you’ve had smallpox or the vaccine against it, you’re immune. When you have the disease, it’s quickly obvious. That makes a strategy of watching for people to display symptoms and then rapidly vaccinating everyone around them (known as “ring vaccination”) an effective approach to stop outbreaks. The same vaccine worked worldwide and it was cheap and stable—it didn’t require refrigeration or complex injection. Other diseases don’t share these features: there’s still no malaria vaccine; many people with polio show few symptoms; Ebola has an animal reservoir. Covid-19 is slower to develop symptoms; many carriers have none. And there’s an animal reservoir in bats. That’s why the complete victory against smallpox has been hard to replicate in the past and would be hard to achieve with Covid-19.
But progress against other infections has been impressive nonetheless. Ali Maow Maalin became a foot soldier in the global fight against polio. “I’m the last smallpox case in the world,” he said. “I want to help ensure my country will not be last in stopping polio.” And Somalia was polio-free at least for the first three months of 2020.
In 1952, more than 50,000 children were paralyzed by a polio outbreak in the United States alone. In 1981, there were only 65,000 new cases reported worldwide. That number dropped to 628 in 2011.41 In 2016, one of the three strains of inactivated polio was removed from the vaccine because it had been confirmed eradicated. At the start of 2020, wild poliovirus was limited to the two countries of Pakistan and Afghanistan.42
This is only one more example of considerable progress thanks to global vaccination efforts. Currently in use in the US are vaccines against twenty-six different diseases—including anthrax, cholera, flu, measles, polio, smallpox, and tuberculosis. Not all are 100 percent effective, but all offer significant protection.43 Fifteen diseases are covered by the vaccinations regularly given to children in the US, and increasingly those same vaccines are being given to children worldwide.
At the start of the 1970s, global vaccination rates against tuberculosis, diphtheria, polio, tetanus, and measles were all below 5 percent. By the end of the decade they’d reached nearly 20 percent. Ten years later they were at 70 percent. And by the end of the century, four out of five children worldwide were fully vaccinated. The number has continued to climb.
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Vaccinations and antibiotics are part of a broader story. As James Riley’s Rising Life Expectancy: A Global History lays out, public health, medicine, rising incomes, improved diets, behavior change, and improved education all played a role in improved global health, with relative contributions varying across time and
geography.44
Take one of the simplest treatments for a major killer, oral rehydration therapy. It was developed by the Indian doctor Dilip Mahalanabis. As a pediatrician specializing in infections of the digestive tract, Mahalanabis was part of a team of researchers studying cures for diarrhea, a mass murderer in India and across the developing world. The condition is the deadly tool of choice for a range of infectious diseases to spread, as we’ve seen.
Mahalanabis’s clinical research was cut short by war. In 1971, East Pakistan—soon to be named Bangladesh—declared its independence from West Pakistan. During the bloody struggle, 9 million refugees fled across the border of East Pakistan into India. Bangaon, in India’s state of West Bengal, was home to a refugee camp of more than 350,000 people. Dr. Mahalanabis was put in charge of health at the camp. As was usual in refugee camps at the time, diarrhea was rampant, linked to appalling sanitation. Mortality rates among infected patients were running at 20 to 30 percent.
“When I arrived, I was really taken aback,” Mahalanabis recalled. “There were two rooms in the hospital in Bangaon that were filled with severely ill cholera patients lying on the floor. In order to treat these people… you literally had to kneel down in their feces and their vomit. Within forty-eight hours of arriving there, I realized we were losing the battle.” He had only two staff members capable of administering intravenous drips—bags of sugar-salt solution piped through a needle into the vein of a patient, the standard medical response to acute diarrhea. And supplies for the intravenous treatment were running out.45 So the doctor tried the approach he’d been researching back in Calcutta.
Mahalanabis found a large drum, filled it with water, added bags of sugar and salt, and stirred. He told family members of diarrhea patients to fill up cans and bottles with the solution and feed it to their suffering relatives until they hated the taste of it.
This “oral rehydration” approach—drinking saline solution rather than “intravenous rehydration” through a needle—could be carried out by anyone with a bucket. It didn’t take skilled care or sterile needles. Even clean water was more of a bonus than a necessity. And patients could tell when they’d swallowed enough of the solution to overcome dehydration. Water with sugar and salt tastes like nectar to the dehydrated and like sweetened seawater to the rest of us. Rather than treating the lucky few who reached the clinic before saline drips ran out, using his simple approach Mahalanabis could help sick people all across the camp. Death rates fell from above 20 percent to 3 percent of diarrhea victims.46
Since 1971, oral rehydration has become a standard treatment for diarrheal disease worldwide. It’s an incredibly cheap and simple response to a massive global killer. But for its full potential to be realized, everyone has to know about it. In the Indian state of Kerala, around 95 percent of parents know it is important to give fluids to a child with diarrhea. In West Bengal—where Dr. Mahalanabis did his lifesaving work over four decades ago—more than half of all parents still give children less to drink when they’ve got diarrhea, which can be a deadly mistake. That’s one reason why child mortality is still higher in West Bengal than in Kerala.
Again, understanding that germs cause disease and washing can remove germs is a powerful piece of knowledge not only for doctors but for all of us, even if clean water and quality sanitation are scarce. Cross-country studies suggest that improving the quality of water supplies can reduce diarrhea risk, but providing education in hygiene practices alongside soap can reduce it twice as much.47
Toward our goal of fully appreciating how worldwide disease has been reduced, consider the guinea worm, which used to be endemic across Africa, the Middle East, India, and the “Stans” of the former Soviet Union. It has been on the retreat since the 1930s, helped by the crusading efforts of former US president Jimmy Carter, who negotiated the “guinea worm ceasefire” in Sudan in 1995.48 The break in fighting allowed volunteers to enter the country to work with communities on avoidance and treatment techniques. In the mid-1980s, there were still 3 million sufferers each year, but in recent years the number of infections worldwide is down to below fifty. The approach didn’t even take a vaccine or deworming drugs—just people filtering their drinking water through a cloth or sieve and disinfecting or avoiding infected water sources.49
Such behavior change has been a vital part of reducing the burden of diseases—from malaria (sleep under a bed net, drain standing water) to HIV (use condoms). It also helps to explain the significant relationship between a mother’s education and her child’s health outcomes.50 Kids born to women who have finished primary school are more likely to live than kids born to women who never went to school or dropped out.
Though drugs and behavior change have been crucial, the more widespread use of older anti-infection tools has delivered a contribution as well. Today, more than two-thirds of the world’s population uses sanitation services considered “at least basic” by the World Health Organization.51 A recent program to chlorinate municipal water in Mexico, for example, increased disinfection coverage from just over half to nine out of ten of Mexico’s population in eighteen months. That reduced the number of children in the country dying from diarrheal disease by more than a third—saving six thousand lives a year.52
Again, people worldwide are eating better, and that makes them less susceptible to infection. The average number of calories eaten by people in Africa each day has climbed from 2,000 per person in the early 1960s to above 2,600 today (although as many as 2 billion people worldwide still don’t get enough vitamins and minerals).53
But the true power of the medical revolution is demonstrated by the considerably improved health outcomes achieved even by people living in extreme poverty without access to improved water and sanitation. Less than one in five urban households in Kenya are connected to the sewage network today, for example. Despite that, infant mortality in Kenya today is around 3 percent—one-third the level in pre-sanitation London.54
What unites vaccination, antibiotics, oral rehydration, bed nets, condoms, and water sieves alike is that their cost is very low and they’re simple to use. Indeed, while we saw in the last chapter that doctors were a comparatively minor part of the sanitation revolution, the story is only somewhat different in the twentieth century. It’s true that the globalization of victory against infection was due in large part to researchers and medical technologies. But the most powerful of those technologies didn’t require an extensive network of practicing doctors and hospitals. Even today the number of doctors and nurses in a country still bears a weak relationship to measures of national health like life expectancy or child mortality.55 If the nineteenth century’s progress against infection was largely a victory of engineering and city management, the twentieth century’s was mostly about vaccine workers, community volunteers, pharmacists, researchers, and the drug industry.
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Between 1900 and 1970, around 70 percent of the decline in mortality in developing countries was driven by lower rates of infectious disease. The biggest contributors were falling rates of respiratory conditions like pneumonia and tuberculosis, where antimicrobial drugs had a huge role to play, and malaria, where better sanitation, bed nets, and quinine-related drugs were effective responses. Since 1970, the drop-off in vaccine-preventable diseases has played a much bigger part thanks to the rollout of immunizations.56 Plague and typhus, both mass murderers in their day, have now been reduced to the mortality bush leagues. We’ve seen that no one dies anymore of smallpox, a disease that killed hundreds of millions in the twentieth century alone.57 Measles, mumps, rubella, diphtheria, pertussis, tetanus—all infect a small fraction of the numbers of decades ago.
That means, worldwide, we’ve seen a transition to modern forms of death. It started later in the developing world than in rich countries, but it’s now far advanced everywhere.58 In Mexico in 1951, influenza, pneumonia, bronchitis, and diarrhea between them still accounted for nearly one third of all deaths, and other infectious causes added close to anoth
er third.59 In Mexico today, the three leading causes of death are heart disease, stroke, and diabetes.
Sometime in the last few decades, the world as a whole crossed a transition point: for the first time since the spread of civilization (at least), more people across the planet died of noninfectious diseases than from infection. Progress has been rapid: by 2010, infectious diseases accounted for only 11 million out of 53 million deaths worldwide—or just over a fifth of all deaths. Many more people across the planet die from cardiovascular conditions like heart failure and stroke than from all infectious causes combined.60
Because infectious diseases strike the (unexposed) young particularly hard, their decline has had the largest impact on child mortality. By the first decade of the twenty-first century, an estimated 2.5 million child deaths were being prevented each year thanks to basic vaccinations alone. Worldwide, in 1800, more than four in ten children born died before their fifth birthday. Even in the richest countries the rate was still above three in ten. Today, the worldwide average is below one in twenty-five.61
Across a range of traditions across the planet, a new child remains without a name until it’s at least a week old. In Jewish and Islamic customs, circumcision occurs on the eighth day (Leviticus 12:1–8). Ghanaian custom was to wait to name the child until the fortieth day; Ethiopian children got a third and final name only after surviving measles.62 But, thanks to improved child health, norms are changing.
In the US, more and more parents are announcing the name of their child before it’s even born, and holding elaborate baby showers months before the due date.63 Bill Gates, the Microsoft founder whose charitable foundation has been so pivotal in backing global efforts against disease, has discussed a trip he took to Ethiopia where he met Sebsebila Nassir—a woman who was, herself, named weeks after her birth and who waited a month to name her first child, but who felt confident enough in the survival of her latest child—Amira—to name her immediately at birth.64 That makes sense—in 1971, almost one-quarter of all kids born in Ethiopia died before their fifth birthday. By the time Amira was born, the corresponding mortality level had dropped to 6 percent.
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