* * *
—
We now know that the agent was a previously unknown virus that would soon be given the name Ebola. The virus is a member of the filovirus family, and it is a parasite that exists, normally, in some creature that inhabits the ecosystems of Equatorial Africa. This creature is the natural host of Ebola. It may well be a type of bat, or some small animal that lives on the body of a bat—possibly a bloodsucking insect, a tick, or a mite. Occasionally a few particles of Ebola escape from Ebola’s natural host and enter the bloodstream of a person. The virus begins replicating in the person’s cells.
Ebola multiplies to extreme concentrations in the bloodstream. When a person dies of Ebola, a drop of their blood the size of the “o” in this text can easily contain a hundred million particles of Ebola. Ebola can destroy a person’s immune system in seven to ten days. HIV requires years to wipe out a person’s immune system. Ebola patients typically become disoriented or deranged: The virus affects the brain in some unknown way, and it causes a change in the person’s facial expression, giving the face a masklike appearance. Ebola patients die suddenly, in a cascade of shock, and often, at the point of death, their bodies shake with tremors and seizures. Nobody knows exactly what Ebola does to the human body as it destroys it: When a person dies of Ebola virus disease, the cause of death is unknown.
Despite its ferocity in humans, Ebola is a life form of mysterious simplicity. A particle of Ebola is made of only six structural proteins, knitted together to become an object that resembles a short strand of cooked spaghetti. An Ebola particle is only around eighty nanometers wide and a thousand nanometers long. If an Ebola particle were the size of a real piece of spaghetti, then a human hair would be about twelve feet in diameter and would resemble the trunk of a giant redwood tree.
Experiments suggest that if one viable particle of Ebola enters a person’s bloodstream, it can cause a fatal infection. Ebola is transmitted among people through direct contact with liquids that come from the body, especially blood and sweat. Once an Ebola particle enters a person’s bloodstream, it drifts until it sticks to a cell. The particle is pulled inside the cell, where it takes control of the cell’s machinery and causes the cell to start making copies of it. Most viruses use the cells of specific tissues to copy themselves. For example, many cold viruses replicate in the sinuses and the throat. Ebola replicates in all tissues of the body except for the skeleton and the large muscles of the skeleton, and it has a special affinity for the linings of blood vessels. After about eighteen hours, the infected cell is releasing thousands of new Ebola particles, which sprout from the cell in threads, until the cell has the appearance of a ball of tangled yarn.
Each Ebola particle is studded with about three hundred soft knobs. The knobs help the particle get inside a human cell. Inside each Ebola particle is a tube made of coiled proteins, which runs the length of the particle, like an inner sleeve. Viewed with an electron microscope, the sleeve has a knurled look. Like the rest of the particle, the sleeve has been shaped by the forces of natural selection working over long stretches of time. Ebola’s family of viruses, the filoviruses, appear to have been around in some form for millions of years. Within the inner sleeve of an Ebola particle, invisible even to a powerful microscope, is a strand of RNA, the molecule that contains the virus’s genetic code, or genome. The code is contained in nucleotide bases, or letters, of the RNA. These letters, ordered in their proper sequence, make up the complete set of instructions that enables the virus to make copies of itself.
By one recent count, an Ebola particle has 18,959 letters of code in its genome. This is a small genome, by the measure of living things. The human genome, for example, has around 3.2 billion letters of DNA code, and the loblolly pine has 22 billion letters of code. Viruses such as Ebola, which use RNA for their genetic code, are prone to making errors in the code as they multiply. These errors are called mutations.
Ebola is one of a class of pathogens known as emerging viruses. An emerging virus, typically, is one that naturally infects some species of wild animal but is also capable of infecting humans. The virus can jump from its wild host into a person and can begin replicating in the person. This is a process known as the cross-species jump of a virus. According to genomic scientists who study the code of viruses, viruses have been doing cross-species jumps, moving from one kind of host to another, for billions of years. Typically a virus mutates rapidly as it moves into a new kind of host. The virus’s genetic code starts changing as it encounters new conditions in a new host. The virus is adapting to its new host, ensuring its survival through the ages.
After making a cross-species jump from an animal into a person, an emerging virus can start moving from person to person, starting chains of infection, expanding its range in its new human host. A virus that is making a cross-species jump out of an ecosystem into people can be thought of as a wild creature in its own right. Like many wild creatures, an emerging virus can be unpredictable and dangerous.
At Yambuku, in 1976, a few particles of Ebola slipped out of an animal that lives in the central African rain forest and got into the bloodstream of one person. The first human victim of Ebola at Yambuku has never been identified. The person may have been a forty-two-year-old schoolteacher at the Yambuku mission named Antoine Lokela, who died in the mission hospital on September 8, 1976, with severe hemorrhages coming from the openings of his body. He gave the virus to his wife, Sophie Lisoke, who broke with Ebola and nearly died, but survived her illness. Sophie Lisoke was the first known survivor of Ebola disease.
From the body of its first victim the virus started moving—ancient, opportunistic, adaptable, cunning in a biological sense. Ebola’s only mission was to never stop replicating, and to never stop moving from person to person, and thereby to make itself immortal in the human species.
Nobody knew then, nor does anybody know now, where emerging viruses are going or what one of them might become. The human host has been gathering itself into gigantic supercities, teeming urban megahives packed with tens of millions of individuals jammed into a small space, who are breathing one another’s air and touching one another’s bodies. The supercities are growing larger all the time. Many of the world’s largest supercities are crowded with people who have little or no access to doctors and medical care. The cities are connected by airline routes, and the human host has zero immunity to any emerging virus.
Ebola is roughly as contagious as seasonal flu.
PART TWO
HEAT LIGHTNING
THE WASHING POOL
Thirty-seven years later
UPPER MAKONA RIVER, WEST AFRICA
December 2013
The Kissi people of West Africa, who speak their own language and have their own traditions, live in a green countryside, scattered with hills, which spreads across parts of Sierra Leone, Guinea, and Liberia—three small nations that are grouped together along the West Coast of Africa. The Kissi territory covers an area where the national borders of the three countries converge in a triskelion, or triple spiral. Long stretches of the borders follow the course of the Makona River. A narrow, olive drab river broken by occasional rapids, the Makona winds through Kissi lands and then runs southwest through Sierra Leone until it ends in the Atlantic Ocean. In this book the Kissi lands surrounding the river will be called the Makona Triangle. The people of the Makona Triangle cross the river and travel among the three countries constantly, visiting relatives, doing business, seeking medical care, and they pay little attention to which of the three countries they happen to be in at a given moment.
The Makona Triangle lies at the northern end of a belt of tropical forest and natural grassland that once extended for a thousand miles along the curving coast of West Africa, from Guinea down to Ghana. The West African forest is an ecosystem of immense biodiversity. It is populated with hundreds of different species of trees, together with many kinds of grasses, shrubs, vines, ferns
, and mosses, and it is a home to chimpanzees, fungi, elephants, lichens, antelope, algae, protozoa, monkeys, slime molds, mites, bats, segmented worms, smooth worms, rodents, frogs, birds, insects, spiders, and truly astronomical numbers of bacteria. The West African forest also contains an ocean of viruses.
This ocean of viruses in the world of living nature is known as the virosphere. The virosphere includes all viruses as well as infective proteins called prions. The biosphere, as distinct from the virosphere, is the universe of organisms that are made of cells. The biosphere includes everything alive, from tigers to black slime on rocks. All living organisms in the biosphere are made of cells—single-celled organisms and multicellular organisms alike.
The virosphere and the biosphere exist together and interpenetrate each other, like milk in tea, like mist in air. Everything that lives gets infected with viruses. As far as anyone knows, viruses replicate in the cells of all species of living things, all of them, from bacteria to blue whales. The virosphere permeates the earth’s atmosphere, which is filled with viruses blowing in the wind. Around ten million virus particles land on every square meter of the earth each day, drifting down from the air. Viruses saturate the soil and the sea. A liter of seawater contains more virus particles than any other form of life. Viruses exist in vast numbers in the human gut, infecting all of the four thousand different kinds of bacteria that live naturally in a person’s intestines. Viruses can sometimes infect other viruses. A giant virus named the Mamavirus, which was discovered infecting amoebae that live in a water-cooling tower in Paris, gets infected by a small virus called the Sputnik. A Mamavirus particle with Sputnik disease is one sick virus—deformed and unable to replicate very well.
Almost all viruses in any ecosystem are unknown to science.
In recent decades, much of the West African forest has been cut down. At the same time, the human population has grown dramatically. What were once villages have become small cities, and small cities have become metropolises of millions. As this happened, the forest was steadily eaten away and turned into small fragments. The wild grasslands were cultivated, and the land became a quilt-work of cassava fields, rice fields, plantations of oil palms, groves of cocoa trees, and large tracts of a type of dense, brushy thicket called farmbush. Even so, many small pieces of the ancient West African forest remain, especially on the summits of hills, where a stand of old trees can form a kind of topknot, as if the trees have gathered themselves into a defensive huddle against a besieging enemy.
The Kissi people regard the remaining bits of wild forest as sacred places. The chiefs of villages protect these forest patches, and won’t allow anyone to cut down a tree in a sacred patch. Kissi people hold ceremonies and bury their dead there, and the spirits of family ancestors dwell in the forest patches. In biological terms, the fragments of old forest in West Africa are the remains of a primeval ecosystem that has existed for millions of years and is now under threat and disappearing. The remaining fragments of wild forest have become zones of contact where the life forms that still exist in the forest mix with the human world.
In older times, when large tracts of unbroken forest still existed, Kissi hunters pursued antelope, monkeys, duiker, elephants, and buffalo. With the breakup of the forest, the game animals have largely disappeared or become very scarce. These days, Kissi hunters devote themselves to trapping cane rats and shooting bats. The cane rat is a meaty rodent that can grow as big as a raccoon, and it inhabits grassland and farmbush. The most highly prized bats are fruit bats, also called flying foxes. They are large bats with cinnamon fur, large, alert eyes, and a pointed nose, like a fox. A well-aimed shotgun blast into the top of a palm tree can bring down ten or twenty flying foxes at once. The meat of a flying fox is said to have a mild taste. Local people cook it into a sauce that’s poured over rice.
There’s another kind of bat that Kissi people call the lolibelo or flying mouse. Flying mice are small and gray, and have a thin, hairless tail, like a mouse, and they can crawl surprisingly fast. They eat insects rather than fruit. Flying mice stink; they give off an acrid reek that smells like mouse piss. Many Kissi adults refuse to eat flying mice. Kissi children, on the other hand, do eat them. They don’t seem to mind the smell as much as adults do.
In a Kissi village called Meliandou, which is in the Makona Triangle in Guinea, the children liked to play at the foot of a dead tree that smelled bad. Meliandou is situated below a deforested hill. It is about five miles from the Makona River and the border with Liberia, and is about fourteen miles from Sierra Leone. The village is a tight group of thirty-one houses, plus a schoolhouse and a tiny medical clinic. The houses are made of mud bricks or concrete blocks, and have metal roofs, stained with rust. Like many Kissi villages, Meliandou is encircled by a small forest, a deep ring of trees. Most of the trees in Meliandou’s ring forest have been planted by people, and their harvest is used for food and sold for cash. There are cacao trees, oil palms, and mangos in Meliandou’s ring forest—but mixed in among them are a few wild trees, with heavy trunks and magisterial crowns. A stream flows through Meliandou’s ring forest and goes down to a pool, where the women of the village wash clothes, bathe, and wash their children. The smelly tree stood near the washing pool. It was tall and hollow, a silver relic of a vanished ecosystem. Kids liked to play around the tree while their mothers were washing at the pool. They would hide behind the tree’s fluted buttresses, which came out of the tree in thin blades arranged in a star around the base of the tree, and they liked to crawl inside the tree through a hole in its base. The hole opened up into a cave that ran upward through the center of the tree and out of sight. The tree cave was full of stinky flying mice.
In mid-December 2013, a woman of the village named Sia Dembadouno took her two-year-old son, Émile Ouamouno, and probably her daughter, four-year-old Philomène, down to the washing pool. While the mother was at the pool, it seems that little Émile wandered off with a group of older children and played around the dead tree.
The children of Meliandou would sometimes build a small fire inside the cave at the base of the tree. The smoke would go up through the hollow tree, and the bats would get annoyed and start flying out. Some would get smoke-addled, fall down, and land in or near the fire. The older children would gather around the hole at the base of the tree, holding sharpened sticks, and they’d spear the bats. They roasted the bats over the fire on their sticks as if they were marshmallows. Unlike some adults, the kids had no problem eating flying mice. They would eat the roasted bats straight off the stick, and they often shared bat-on-a-stick with one another. Émile was a toddler, too small to be able to kill or cook any bats, but he might have tasted a raw or undercooked bat, or he might have played with a groggy bat, or he might have gotten some bat blood or bat urine in his eyes or in a cut in his skin.
Or the little boy might have gotten a bite from a bat fly. A bat fly is a blind, wingless fly that drinks the blood of bats. It has long, jointed, hairy legs, like a spider, and it is a good crawler. Bat flies are found in bat roosts, where bats hang crowded together, and the flies crawl from bat to bat, sucking their blood. Possibly a bat fly crawled onto Émile and bit him. The fly might have had some bat blood in its mouthparts, and might have injected a small amount of bat blood into the boy. The bat blood may have been contaminated with a few particles of a virus. This is all speculation. Nobody actually knows how Émile got infected. All we know is that a few particles of a virus, maybe only one particle of a virus, emerged from the virosphere and entered the little boy.
On Christmas Eve, the boy came down with diarrhea. It turned into a black liquid, and he died on December 28, in his mother’s arms. A week after Émile died, his four-year-old sister, Philomène, also got black diarrhea and died. In villages in Africa where houses don’t have running water, women often use their bare hands and saliva to clean children who throw up or soil themselves. After Philomène’s death, the children’s mother came down wi
th a fever. She died on January 11, 2014. She was twenty-five at the time of her death. Her family buried her next to her house, as is the tradition in West Africa. Shortly afterward, her mother, Philomène’s and Émile’s grandmother, started vomiting and died a few days later.
The village midwife had nursed the children’s mother and grandmother while they were sick. Not long afterward, the midwife broke with a fever. By this time the village was starting to get really frightened by the chain of deaths. The midwife’s relatives got very worried about her and took her to a hospital in a small city called Guéckédou. The city, with a population of 200,000, is in Guinea. It is seven miles from Meliandou. The midwife died in the Guéckédou hospital. Then a medical worker at the hospital, who’d taken care of the midwife as she died, came down with the sickness. This medical worker decided to seek care at a hospital in a town called Macenta, which is forty miles from Guéckédou. The medical worker died at the Macenta hospital. The illness now began moving around Macenta, as well as moving around Guéckédou. A viral lightning bolt had come out of the forest and struck a little boy. The child had been killed, and he had started a chain of infections in a few more people. The virus started amplifying itself in two places in Guinea, and then it jumped to more places, and soon a viral fire was smouldering in the Makona Triangle.
Months later, after the fire had gotten bigger and had been noticed, an expert in viruses named Fabian Leendertz, who works at the Robert Koch Institute in Berlin, spent eight days in Meliandou village with a team of colleagues, including an anthropologist, in an effort to trace the origin of the virus back into the ecosystem. It came down to a question of exactly how little Émile might have gotten infected in the first place. The boy was the first identified case of the disease—the index case. Apparently the virus had leaked out of some wild animal and gotten into the boy. His body had been the bridge over which the virus had traveled in its passage from the virosphere into the human species. But exactly what kind of creature had the virus come from? Where in the ecosystem did the virus hide?
Crisis in the Red Zone Page 4
