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Ebola — which first appeared in 1976 in the Congo and Sudan — is a brutal virus, with some strains killing up to 90 percent of people infected. People infected with Ebola, which is transmitted through bodily fluids such as blood, vomit, and diarrhea, can remain symptomless for between 2 and 21 days before being stricken with flu-like symptoms, diarrhea, and vomiting which can lead to the hemorrhaging of the eyes, mouth, and internal organs.

The current outbreak in West Africa is the biggest yet, killing 672 people since February, including at least two American citizens. The disease could potentially start spreading even faster after a Liberian man infected with the virus was allowed to board a plane that made a stopover in Ghana, changed planes in Togo, and died in Lagos, the world's fourth most populous city.

Some even worry that the disease could spread to the U.S. after the wife and children of a Texan doctor who came down with the virus were allowed to fly back to America. CDC director Tom Frieden says the CDC is ready for the possibility: "We do not anticipate this will spread in the U.S. if an infected person is hospitalized here, but we are taking action now by alerting healthcare workers in the U.S. and reminding them how to isolate and test suspected patients while following strict infection control procedures."

The only happy news is that the disease is showing signs of becoming more treatable. Deborah-Fay Ndhlovu of Nature points to a 2012 study that showed that "monkeys infected with Ebola have been cured by a cocktail of three antibodies first administered 24 hours or more after exposure. The result raises hopes that a future treatment could improve the chances of humans surviving the disease caused by the deadly virus."

But sadly, even if this research leads to an effective human treatment, a cure in monkeys is no use to humans infected today.