Two years after Parker’s terrible death, on May 8, 1980, the World Health Organization announced that smallpox had been eradicated from Earth, the first and so far only human disease to be made extinct. Officially just two stocks of smallpox remain in the world now—in government freezers at the Centers for Disease Control in Atlanta, Georgia, and at a Russian virology institute near Novosibirsk in Siberia. Both countries have several times promised to destroy the remaining stocks but never have. In 2002, the CIA claimed there were probably also stocks in France, Iraq, and North Korea. No one can say whether, or how many, samples may survive accidentally as well. In 2014, someone looking through a storage area at a Food and Drug Administration facility in Bethesda, Maryland, found vials of smallpox dating from the 1950s but still viable. The vials were destroyed, but it was an unnerving reminder of how easily such samples can be overlooked.
With smallpox gone, tuberculosis is today the deadliest infectious disease on the planet. Between 1.5 and 2 million people die of it every year. It is another disease that we have mostly forgotten, but only a couple of generations ago it was devastating. Lewis Thomas, writing in The New York Review of Books in 1978, recalled how hopeless all treatments for TB were in the 1930s when he was a medical student. Anyone could catch it, he noted, and there was really nothing you could do to make yourself safe from infection. If you got it, that was it. “The hardest part of the disease, for both the patient and the family, was that it took so long to die,” Thomas wrote. “The only relief was a curious phenomenon near the end, known as spes phthisica, when the patient suddenly became optimistic and hopeful, even mildly elated. This was the worst of signs; spes phthisica meant that death was coming soon.”
As a scourge, TB actually got worse as time passed. Until late in the nineteenth century, it was known as consumption and was believed to be inherited. But when Robert Koch discovered the tubercle bacillus in 1882, the medical community realized beyond doubt that it was infectious—a far more unnerving proposition to loved ones and carers alike—and it became more widely known as tuberculosis. Victims were previously sent to sanatoriums entirely for their own sake; now there was a more urgent sense of exile.
Almost everywhere patients were subjected to harsh regimens. At some institutions, doctors reduced patients’ lung capacity by cutting nerves to their diaphragm (a process known as a phrenic crush) or by injecting gas into their chest cavity so that the lungs couldn’t fully inflate. At Frimley Sanatorium in England, authorities tried the opposite tack. Inmates were given pickaxes and made to do hard, pointless labor in the belief that that would strengthen their wearied lungs. None of these did, or possibly could do, the slightest bit of good. In most places, however, the approach was simply to keep patients very quiet to try to stop the disease from spreading from their lungs to other parts of their bodies. Patients were forbidden to talk, write letters, or even read books or newspapers for fear that the content would unnecessarily excite them. Betty MacDonald, in her popular and still very readable 1948 book, The Plague and I, about her own experiences in a TB sanatorium in Washington State, recorded that she and other inmates were allowed visits by their children just once a month for ten minutes and by spouses and other adults for two hours on Thursdays and Sundays. Patients were not allowed to talk or laugh unnecessarily or to sing ever. They were ordered to lie perfectly still for most of their waking day and not permitted to bend over or reach for things.
If TB is off the radar for most of us, that’s because 95 percent of its more than a million and a half annual deaths are in low- or middle-income countries. About one in every three people on the planet carries the TB bacterium, but only a small proportion of those contract the disease. But it is still around. About seven hundred people a year die from tuberculosis in America. Some boroughs of London now have rates of infection that nearly match those of Nigeria or Brazil. No less alarmingly, drug-resistant strains of TB now account for 10 percent of new cases. It is entirely possible that we could one day in the not too distant future be facing an epidemic of TB that medicine cannot treat.
Lots of historically formidable diseases are still out there, not quite entirely vanquished. Even bubonic plague is still around, believe it or not. The United States averages seven cases a year. Most years there are one or two deaths. And there are lots of diseases in the wider world from which most of us in the developed world are spared—diseases like leishmaniasis, trachoma, and yaws, which few of us have even heard of. Those three and fifteen others, known collectively as neglected tropical diseases, affect more than a billion people worldwide. More than 120 million people, to take just one example, suffer from lymphatic filariasis, a disfiguring parasitic infection. What is particularly unfortunate is that a simple compound added to table salt could eliminate the filariasis wherever it appears. Many of the other neglected tropical diseases are beyond horrible. Guinea worms grow up to a meter long inside the bodies of their victims, then escape by burrowing out of their skin. The only treatment, even now, is to speed the process of exit by winding the worms onto a stick as they emerge.
To say that much of our progress against these diseases has been hard won is to put it mildly. Consider the contribution of the great German parasitologist Theodor Bilharz (1825–62), who is often called the father of tropical medicine. His entire career was devoted, at constant risk to himself, to trying to understand and conquer some of the world’s worst infectious diseases. Wishing to better understand the truly horrid disease schistosomiasis—also now sometimes called bilharzia in his honor—Bilharz bandaged the pupae of cercariae worms to his stomach and took careful notes over the following days as they burrowed through his skin en route to invading his liver. He survived that experience but died soon afterward, aged just thirty-seven, while trying to help stop a typhus epidemic in Cairo. Similarly, Howard Taylor Ricketts (1871–1910), the American discoverer of the bacterial group rickettsia, went to Mexico to study typhus but contracted the disease himself and died. His fellow American Jesse Lazear (1866–1900), from the Johns Hopkins Medical School, went to Cuba in 1900 to try to prove that yellow fever was spread by mosquitoes, caught the disease—probably by intentionally infecting himself—and died. Stanislaus von Prowazek (1875–1915), of Bohemia, traveled the world studying infectious diseases, and found the agent behind trachoma, before succumbing to typhus himself in 1915 while working on an outbreak at a German prison. I could go on and on. Medical science has never produced a more noble and selfless group of investigators than the pathologists and parasitologists who risked and all too often lost their lives in trying to conquer the most pernicious of the world’s diseases in the late nineteenth and early twentieth centuries. There ought to be a monument to them somewhere.
III
IF WE DON’T die so much from communicable diseases anymore, plenty of other maladies have stepped in to fill the gap. Two types of diseases in particular are more visible now than they were in times past, in part at least because we aren’t being killed off by other things first.