It’s one of the deadliest diseases on Earth, with a fatality rate as high as 90 percent. It’s also grotesque, sometimes causing bleeding from the eyes, ears, mouth and rectum and a bloody rash leading to a quick demise. It’s Ebola, one of a handful of illnesses that are so deadly governments consider them a threat to national security. The latest epidemic has killed more people than all previous waves combined. For the first time Ebola infection occurred outside Africa.

The Situation

In late January, the World Health Organization said that for the first time in seven months there were fewer than 100 new confirmed cases of Ebola in the hardest hit countries: Liberia, Sierra Leone and Guinea. According to the official count, more than 22,000 people have been infected since December 2013 and about 8,800 have died. More will perish, given a fatality rate of 70 percent in this outbreak. The U.S. Centers for Disease Control and Prevention estimated that actual cases were 2.5 times higher. The epidemic, the first in West Africa, spread to NigeriaSenegal and Mali, which successfully contained it. Early on, the disease was transmitted by victims who avoided hospitals because of stigma and fear, as well as by unsafe burial practices. Efforts to control the epidemic were hampered initially by a shortage of trained workers at a time when humanitarian groups were dealing with many crises elsewhere. The U.S. responded by sending hundreds of military personnel to Liberia, which in October 2014 began to see a reduction in cases. Ebola jumps to humans through contact with secretions from animals such as chimpanzees, gorillas and bats. It spreads among humans the same way, with medical workers and family members the most at risk. In the first known instance of Ebola transmission outside Africa, medical workers in the U.S. and Spain were infected after caring for people who had contracted Ebola in Africa. A separate outbreak killed 49 people in the Democratic Republic of Congo before it was contained.

The Background

Researchers think bats are the most likely host of Ebola, which was first identified in 1976 near the Ebola River in what is now the Democratic Republic of Congo. Earlier outbreaks were contained within months. Prior to the current wave, a total of 2,387 cases had led to 1,590 deaths. There are no drugs or vaccines approved to treat or prevent Ebola. The rarity of the disease and its prevalence in rural areas of poor African nations have provided little incentive for big drugmakers to invest in treatments, leaving smaller biotechnology firms and government-funded labs to take up the challenge. Now companies including GlaxoSmithKline and Johnson & Johnson are accelerating development of vaccines, which would command a larger market than treatments. The CDC lists the virus, alongside anthrax and smallpox, as a Category A bioterrorism agent.

The Argument

Ebola doesn’t travel through the air, making it harder to transmit than many other pathogens as long as proper health-care practices are followed. Other diseases have killed many more people. Influenza, for example, kills up to half a million people a year around the globe. Nevertheless, Ebola’s tear through some of the world’s poorest countries — Liberia has just 1 doctor per 100,000 people – raises questions about whether richer countries and the WHO responded quickly enough and whether aid should focus more on strengthening health-care systems. The presence of Ebola in the U.S. and Europe provoked debate about what precautions, such as quarantines, are appropriate to prevent its spread.

The Reference Shelf

  • Bloomberg News Q&A on the Ebola outbreak.
  • Read fact sheets on Ebola at the Centers for Disease Control and Infection (CDC), World Health Organization (WHO), and the National Institutes of Health (NIH).
  • A Bloomberg News article on an Ebola treatment being developed at Mapp Biopharmaceutical in San Diego, which is working with the U.S. Defense Advanced Research Projects Agency, the National Institutes of Health and the Defense Threat Reduction Agency.
  • Richard Preston’s 1994 best-selling book about Ebola, “The Hot Zone” and Laurie Garrett’s 1995 book “The Coming Plague: Newly Emerging Diseases in a World Out of Balance.”
  • A New York Times graphic tracing the 2014 Ebola epidemic.

First Published April 4, 2014

To contact the writer of this QuickTake:

Makiko Kitamura in London at mkitamura1@bloomberg.net

To contact the editors responsible for this QuickTake:

Leah Harrison Singer at lharrison@bloomberg.net

Lisa Beyer at lbeyer3@bloomberg.net