A hunter comes across a sickly gorilla, too weak to defend itself from the blows of his cleaver. Perhaps it’s already dead—many locals have no problem eating animals found dead of unknown causes, viewing them as gifts from forest spirits.
The hunter takes the carcass home and butchers it. Naked hands and arms are unguarded from the gorilla’s blood and viscera, and equally vulnerable to a careless butcher’s blade. A knick to a finger while handling infected meat is more than enough for the thin, threadlike virus to make its way into its first victim. The incubation period can be as short as two days or as long as two weeks, but on average, it will take four to six days for the hunter to first notice the symptoms of Ebola virus infection.
Every few years, Ebola makes a resurgence in the poorer, more remote corners of Africa, sickening a few dozen tribespeople and the doctors who treat them before retreating into the jungle’s dark interior. This time, though, Ebola isn’t fading—it’s spreading. There are now 125 confirmed or reported cases in four West African nations, including Guinea, Liberia, Mali, and Sierra Leone. The death toll has risen above 90. The disease has even spread to Guinea’s capital, Conakry, a city of 2 million. Terrified officials are installing thermal scanners in the region’s airports to screen passengers for fevers; doctors dressed in protective “space suits” have done little to halt the fear.
Recorded outbreaks of the Ebola virus have decimated gorilla populations in Central Africa; between 2001 and 2005, at least 5,500 gorillas—more than 90% of the population —were killed at the Lossi Sanctuary in northwest Republic of Congo alone. The bushmeat trade, which involves the illegal butchering and handling of gorilla meat, is a highway on which the virus travels to break the animal-human barrier.
The onset is sudden but non-distinctive: Ebola’s blistering fever, chills, headaches, vomiting, and fatigue are similar to the numerous other infectious diseases endemic to the jungles of Central Africa. It’s not until the disease progresses for two or three days that the hallmark hemorrhaging begins. Patients begin to bleed from their gums, digestive tract, and lungs, with a bruise-like rash spreading across the bodies of many patients. Skin can tear off if it’s touched. Some patients go blind, others lose the surface of their tongues after waves of black, blood-tainted vomit. Internal organs like the spleen swell up and become as hard as sausages. Depending on the strain, anywhere from 50% to 90% of patients succumb within two weeks of infection. There is no cure.
Ebola’s feared virulence has actually done more to quarantine the virus in the remote forests of Central Africa than any human intervention. Bushmeat hunters can only travel so far on foot, and once infected, Ebola almost always wins the race against time. Unlike HIV, another African virus that can remain dormant and contagious for years, Ebola’s short incubation period, the relative difficulty of spreading via bodily fluids, and the speed of its lethality hobble any potential for a worldwide epidemic. The difference a short incubation period makes is stark: to date, Ebola has only killed 1,636 people since its discovery, while AIDS has killed 36 million. The majority of its victims are typically doctors and nurses, infected by close contact with the infected—a patient who is hemorrhaging to death tends to leave a trail of infectious bodily fluids—and by the needle pricks that are all-too common in poor, remote hospitals that lack proper equipment and hygienic practices.
Discounting the occasional outbreak among bushmeat hunters, Ebola seems content to lurk. Virologists and epidemiologists have hunted for the virus’s natural reservoir since its discovery in 1976. More than 30,000 plants, mammals, birds, reptiles, amphibians, and insects have been tested, with no success. Bats are the most likely culprits—the “Patient Zero” victims of multiple outbreaks in the 1970s worked in cotton factories infested with them, and the feet-deep guano inside the volcanic caves of Uganda’s Mount Elgon may have been the source of contemporary outbreaks of Marburg, Ebola’s kissing cousin virus. Generally, avoiding gorilla meat and guano in Central African forests has been enough to ensure a long, hemorrhagic fever-free life.
That is, until Ebola stopped being so remote. Journeys that once took weeks by foot now take hours by air, and companies eager to plunder the treasures of Africa’s mysterious interior have thrown open the gates that once kept viruses like Ebola contained. The current outbreak in Guinea and Liberia has relief workers with aid organization Doctors Without Borders labeling it “an epidemic of a magnitude never before seen in terms of the distribution of cases.” By unknown means, the virus has been able to travel nearly 3,200 miles from its Central African home to Liberia and Guinea. It’s a feat that has only been replicated by Ebola once before.
Each year, roughly 21,000 primates are imported to the United States from tropical regions around the world. Imported monkeys must be held in quarantine for thirty days before they are shipped anywhere else in the United States. In 1989, at a quarantine facility in the D.C. suburb of Reston, Virginia, a shipment of a hundred crab-eating macaques bound for cosmetic and pharmaceutical testing came in. Within a few days, many of the monkeys held for quarantine started to die, leaving behind traces of blood in their intestines, spleens hardened into blood clots the size of tangerines, and dead cells that, when an intern them viewed under a microscope, appeared to have been blown apart by a virus in the tell-tale shape of a shepherd’s crook. Most alarming of all, many of these monkeys appeared to have contracted their fatal illness through the air.
After the Washington Post announced “Deadly Ebola Virus Found In Va. Laboratory Monkey,” military scientists downplayed the significance of one of the world’s deadliest infectious agents, but samples sent to the United States Army Medical Research Institute of Infectious Diseases in Maryland showed a new strain of the Ebola virus, as well as the virus responsible for Simian Hemorrhagic Fever, an Ebola-like disease that only affects non-human primates. Since viruses are traditionally named after the location of their discovery, the macaque-killing virus became known as Ebola Reston.
Of the 178 people who had contact with the infected monkeys at the Reston Quarantine Unit, six seroconverted. After a breathless waiting period in which the infected were quarantined, none of the six fell ill. Ebola Reston, it seemed, could infect humans, but never became symptomatic. According to the World Health Organization, since Ebola Reston’s discovery, “only 15 persons have been shown to be positive for Reston ebolavirus antibodies… None of these people recalls any significant illness that could be related to infection with Reston ebolavirus.”
Nevertheless, an Ebola scare mere minutes from the U.S. capital was enough for the Centers for Disease Control to slap a heavy set of restrictions on primate importers, tightening testing and quarantine procedures and revoking the licenses of companies involved in the importation of the infected macaques.
One troubling fact remains about this seemingly “safe” Ebola: The macaques at the Reston quarantine facility came not from Central Africa, the home of Ebola, Marburg, and all their virulent cousins, but from the Philippines. How does an African virus find its way to the jungles of Southeast Asia? One possibility is that Ebola has already managed to travel halfway around the world to carve out a biological niche. As borders close in West Africa and doctors armed with modern quarantine techniques swarm affected areas, this latest Ebola outbreak will likely burn itself out, but now that Ebola has proven itself capable of traveling thousands of miles undetected, the location of the next outbreak is a mystery.