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You'll Probably Never Catch Ebola—So Why Is the Disease So Terrifying?

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These are jittery times. It’s high summer, and the current outbreak of Ebola is worsening. The World Health Organization reports that just under one thousand people have died so far, 45 of them in the past two days alone; the Centers for Disease Control has issued its highest-level alert. The stories out of the affected areas are horrific. The New Yorker notes that in the town of Kemena, in Sierra Leone, 18 doctors and nurses who had been caring for Ebola patients have fallen ill, and five have died. These doctors and nurses worked in biohazard suits, but got sick anyway, and it’s impossible to read this last detail without a shiver of dread.

Efforts to contain the disease have gone poorly. Quarantines are in place in the affected countries, but enforcement has been uneven, hampered by ignorance in some cases—The New York Times filed an unsettling story from Freetown about neighbours of an Ebola victim gathering to mourn in her home, despite the strict isolation order that was supposed to be in effect—and a sheer lack of resources in others. Medical systems are overwhelmed. The countries involved have taken to screening departing air travelers for the disease, but Ebola has an incubation period of up to 21 days, meaning that it’s disconcertingly possible for a passenger to contract Ebola in an affected country, fly out of West Africa in seemingly perfect health, and then begin exhibiting symptoms on the other side of an ocean some days later.

I live in New York City, which is to say, in a city serviced by three international airports. I assume Ebola will eventually appear here. The disease seems to me to be a distant risk at present, because it isn’t airborne. It’s a danger I’d rank well below, say, the ever-present possibility of being hit by a car on my way to work in the morning. This possibly says more about New York City drivers than it does about Ebola.

I have friends in New York who are afraid. Is their fear justified? I don’t know. By any statistical measure, it makes far more sense to fear flu than to fear Ebola on this continent, but my friends’ fear of Ebola isn’t incomprehensible or even terribly unreasonable. After all, the history of humanity is also a history of pandemics, and we’re taught to fear and respect disease from a young age. We’re inoculated before we can speak and taught germ theory in pre-school.

There has very often been an invisible menace traveling toward us. And now, in an age of brisk intercontinental transport and split-second information-sharing, the wildness of plague and pandemic can sometimes feel very close.

In the middle of the first century, Roman soldiers returning from their siege of the Mesopotamian city of Seleucia brought a strange new illness back to the capital. Victims of the Antonine Plague, as it came to be called, developed high fevers, vomiting and diarrhea. After several days of this, terrible pustules bloomed over their skin. There’s no way to be absolutely certain of what afflicted these people, but historians generally agree that the Antonine Plague was smallpox. The population had no immunity. In some parts of the Roman Empire, one in three people died.

The Romans feared they’d brought this calamity on themselves, by their actions in Seleucia. They had ransacked and burnt the city. In Seleucia’s Temple of Apollo, the contemporary historian Ammianus Marcellinus wrote, Roman soldiers had discovered “a narrow hole.” They wondered if perhaps the hole might contain valuables. When the hole was opened,

...from some deep gulf which the secret science of the Chaldæans had closed up, issued a pestilence, loaded with the force of incurable disease, which in the time of Verus and Marcus Antoninus polluted the whole world from the borders of Persia to the Rhine and Gaul with contagion and death.

This touches upon the root of our fear: Illness carries, even now, a terrible mystery. We know a great deal more than we used to about viruses, bacteria, the mechanisms of cells. But even now, we often still don’t always know why some people develop cancer and others don’t, or why some cancers disappear following treatment while others lie dormant, only to blossom over the PET scans with a deathly radiance years later. We don’t always know why some hearts fail and others beat for a century. In flu season, it isn’t always clear why some people get sick while others don’t.

Death by external causes tends to be more explicable, a more straightforward matter of this, therefore that: A missed step on a long staircase, a finger on a trigger, a moment of inattention at the wheel, therefore death. If we’re less afraid of accidents than of illness, it’s because we believe we have some control over the former. Of course, this is often an illusion, but it’s true that some accidents can be avoided, some of the time. Illness frightens us because it’s chaotic. It seems to come from nowhere: You’re fine, and then you’re not. There is an awful randomness about it.

Contemporary historians report that at the peak of the Antonine Plague, 2,000 people were dying every day in Rome. If the explanation the Romans came up with seems a little silly, it’s difficult to fault them for it. There had to be some cause for the catastrophe, they reasoned. If so many people were dying each day, it must be because they’d done something they shouldn’t have; offended a god, opened a hole in a temple that should have remained closed. It is infinitely more terrifying to imagine that such calamity can befall us entirely by chance.

Sixteen centuries after the Antonine Plague, Captain George Vancouver sailed up the west coast of the land that would later be known as Canada. As they sailed north, he and his crew were increasingly disconcerted. This was a rich, fertile land, with a temperate climate, and yet it seemed strangely empty. When they went ashore, they noted dozens of empty villages, bleached skeletons scattered about in the weeds. “I frequently met with human bones during my rambles,” his crew member Thomas Manby wrote. Smallpox had already arrived.

Estimates on how long smallpox has been with us have varied. In a 2009 review published in the journal Archives of Virology, the Russian scientist Sergei N. Shchelkunov makes a compelling case for the disease having made the jump from rodents to humans between three and four thousand years ago. The human misery wrought by the disease is incalculable. In the thousands of years when smallpox was with us, we died by the millions. Populations were decimated. Civilizations fell.

But what were we left with, after all that time? Can one illness protect against another? Smallpox was with us for so long that it changed us physiologically. Most humans have two copies of a gene that produces a receptor, called CCR5, that allows the HIV virus to enter the cells of the immune system. But among people of European descent, approximately 10% have only one of these genes, instead of two. People with this genetic mutation are far less likely to contract HIV, and when they do, the disease progresses more slowly.

Some years ago, scientists at UC Berkeley found that the prevalence of this genetic mutation among Europeans came about due to Europeans’ prolonged exposure to smallpox. In the years when smallpox flared, people who happened to carry the CCR5 mutation were much less likely to catch smallpox, and thus much more likely to survive long enough to give birth to children with the same mutation. In other words, the genetic mutation that protects against HIV also protects against smallpox. Pandemics have always haunted us, but at least one of them lingered long enough to change us in such a way that we were resistant to another illness.

Ebola is very new. The disease made its debut in humans in 1976, not far from the Ebola River in what was then Zaire. Zaire, of course, is now the Republic of Congo, but the old name lives on as a strain of the virus. Ebola-Zaire is the strain from which people are presently dying in Liberia, Guinea, and Sierra Leone.

I hope it won’t be with us for long. I hope that the same forces of technological advancement that make pandemics harder to contain now than before—the dazzling ease of crossing oceans, with or without viral timebombs in our bodies—will lead soon to a vaccine. I hope that our descendants won’t fear Ebola.

What will they fear? They’ll fear something, certainly. After smallpox, there was HIV/AIDS; after Ebola, there will be something else, and then something else after that. It’s tempting to think of these illnesses as a series of assassins, dispatched one after another, and thoughts of assassins always bring me back to Pale Fire. In Vladimir Nabokov’s magnificent late novel, the narrator—Kinbote, a deposed king who once ruled a distant northern land—considers his vulnerability in the wake of an attempt on his life. The assassin, Jakob Gradus, shot the wrong man and is behind bars, but there will be other assassins behind him. Whatever path his life takes, Kinbote considers,

Somebody, somewhere, will quietly set out—somebody has already set out, somebody still rather far away is buying a ticket, is boarding a bus, a ship, a plane, has landed, is walking toward a million photographers, and presently he will ring at my door—a bigger, more respectable, more competent Gradus.

Ebola will end someday, just as smallpox did. But there will always be another Gradus, and there will always be our fear.