Ebola hemorrhagic fever is in the news again, due to an outbreak in Gabon.
Ebola is always news because, unlike most rare tropical diseases, it’s part of pop culture, thanks to Richard Preston’s 1994 best-seller The Hot Zone and Dustin Hoffman’s 1995 movie Outbreak.
As a result, many people follow news of Ebola outbreaks with bated breath, wondering if the disease will break out of Africa and spread unstoppably across the world. After all, didn’t Preston write that Ebola can be seen as Earth’s attempt “to rid itself of an infection by the human parasite”?
Well, if that’s what Ebola is, it’s a pretty pitiful attempt. Ebola hemorrhagic fever has killed fewer than 1,000 people since 1976. Pneumonia kills that many people every year in any large city; around the world, tuberculosis kills five times that many every day. In sub-Saharan Africa alone–Ebola’s stomping ground–malaria kills 700,000 people every year and diarrhea–a joking matter here–kills 900,000.
Ebola is named after a river near Yambuku, Democratic Republic of the Congo, site of the first recognized outbreak. Like the ‘flu, its initial symptoms are fever, weakness, muscle pain, headache and sore throat. Eventually, vomiting, diarrhea and rash develop, the kidneys and liver may stop functioning normally, and, in fatal cases, uncontrollable internal and external bleeding begins, resulting in the vomiting of blood and bleeding from the eyes, ears, nose and other orifices.
Three different strains of Ebola cause disease in humans: Ebola-Zaire, Ebola-Sudan, and Ebola-Ivory Coast. Ebola-Zaire, the deadliest, has killed 90 percent of its victims in some outbreaks; Ebola-Sudan kills about half. Ebola-Ivory Coast has only infected one person that we know of, who recovered. A fourth species of Ebola virus, Ebola-Reston, only causes disease in monkeys (an outbreak in a research facility in Reston, Virginia, gave the strain its name and was the basis of The Hot Zone).
Human Ebola has cropped up in the Democratic Republic of the Congo, Gabon, Sudan, the Ivory Coast, and Uganda. Only a couple of isolated cases have been reported outside of Africa; for instance, a laboratory worker in England became ill after an accidental needle-stick while working with the virus, but recovered.
Ebola isn’t really a human disease at all; instead, it’s apparently carried constantly by some animal or insect (as yet unidentified) and passed on to humans by accident from time to time. Once a human is infected, the disease is transmitted through direct contact with the blood or other bodily secretions (sweat, saliva, etc.) of the infected person, or by contact with objects contaminated with such secretions. No airborne transmission of Ebola has ever been documented in humans, although Ebola-Reston does seem to spread among monkeys that way.
Breaking the chain of transmission is thus relatively easy: medical personnel and family and friends of infected people must avoid contact with bodily fluids by wearing masks, gloves, gowns and goggles. Patients should be isolated from all uninfected, non-medical people, and everything that comes in contact with them should be thoroughly sterilized.
Preventing further transmission of the disease is vital, because there is no effective treatment: at best, patients receive therapy designed to treat the symptoms and prevent fatal shock.
Every time Ebola crops up, someone raises the scenario of a person infected with the disease getting on an airplane, flying here, and causing a major Ebola epidemic in North America. The risk of such at thing is effectively zero, epidemiologists say, first, because Ebola is most contagious during its final stages, when patients are far too sick to even lift their heads, much less travel, and second, because someone exhibiting symptoms would be promptly hospitalized and isolated, limiting transmission to a few cases at worst. (There’s a peculiar Western assumption that Ebola has only appeared in tiny towns buried in the jungle, never in a major city. In fact, Kikwit, Democratic Republic of the Congo, site of a major outbreak in 1995, has a population of 500,000. Yet even there, despite primitive health care facilities and a fairly extended period of time before the disease was recognized, Ebola killed only 315 people.)
Research continues on ways to treat Ebola; there’s even hope of a vaccine. But until that research pays off, the disease will continue to surface from time to time as it has this month, causing terrible suffering and misery–but not posing any threat to the “human parasite.”
Humanity, I’m pleased to say, will go right on infesting the Earth for the foreseeable future.