The Ebola virus, which has caused various outbreaks in Africa since it was first identified in 1976, is one of the deadliest viruses known.

Causing severe bleeding and organ failure, most of the sub-types of the virus kill in 25-90 percent of the people they infect. There are no approved drugs to treat the disease.

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Humans contract Ebola from animals, often from eating infected meat or contact with bat feces or urine. Once one person gets it, it can be spread through body fluids, contaminated needles, and body tissue. The contagious period usually starts after symptoms appear. New infections often occur when family members take care of each other and prepare dead bodies for burial, according to The Mayo Clinic.

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Symptoms, which usually come on quickly, include fever, headache, aches, chills and sore throat, and progress to nausea and vomiting, diarrhea, rash, chest pain and cough, weight loss and bleeding.

In lieu of medication, people are sometimes quarantined to curtail an outbreak.

“Isolation units are essential to prevent the spread of the disease, which is highly contagious,” Dr. Esther Sterk, medicine adviser of the international medical charity Medecins Sans Frontieres, said in a statement.

Image: A transmission electron micrograph image of the Ebola virus. Credit: Dr. Frederick Murphy/CDC