What You Need to Know About the Ebola Outbreak

By Denise Grady, Josh Keller, Heather Murphy and Sergio Peçanha.

How many people have died?

More than 1,300 people in Guinea, Liberia and Sierra Leone have contracted Ebola since March, according to the World Health Organization, making this the biggest outbreak on record. More than half of those infected have died. Nigeria also reported one probable case: a Liberian man who traveled there and died on July 25.

How does this compare to past outbreaks?

It is the deadliest, eclipsing an outbreak in 1976, the year the virus was discovered.

How contagious is the virus?

You are not likely to catch Ebola just by being in proximity with someone who has the virus; it is not airborne, like the flu or respiratory viruses such as SARS. Instead, Ebola spreads through direct contact with bodily fluids. If an infected person’s blood or vomit gets in another person’s eyes, nose or mouth, the infection may be transmitted. In the current outbreak, most new cases are occurring among people who have been taking care of sick relatives or who have prepared an infected body for burial. Health care workers are at high risk, especially if they have not been properly equipped with or trained to use and decontaminate protective gear correctly. The virus can survive on surfaces, so any object contaminated with bodily fluids, like a latex glove or a hypodermic needle, may spread the disease.

Why is Ebola so difficult to contain?

In some parts of West Africa, there is a belief that simply saying “Ebola” aloud makes the disease appear. Such beliefs create major obstacles for physicians from groups like Doctors Without Borders, which are trying to combat the outbreak. Some people even blame physicians for the spread of the virus, and turn to witch doctors for treatment. Their skepticism is not without a grain of truth: In past outbreaks, hospital staff who did not take thorough precautions became unwitting travel agents for the virus.

How does the disease progress?

Symptoms usually appear about eight to 10 days after exposure, according to the Centers for Disease Control and Prevention. At first, it seems much like the flu: a headache, fever and aches and pains. Sometimes there is also a rash. Diarrhea and vomiting follow.

Then, in about half of the cases, Ebola takes a severe turn, causing victims to hemorrhage. They may vomit blood or pass it in urine, or bleed under the skin or from their eyes or mouths. But bleeding is not usually what kills the patient. Rather, blood vessels deep in the body begin leaking fluid, causing blood pressure to plummet so low that the heart, kidneys, liver and other organs begin to fail.

How is the disease treated?

There is no vaccine or cure for Ebola, and in past outbreaks the virus has been fatal in 60 to 90 percent of cases. All physicians can do is try to nurse people through the illness, using fluids and medicines to maintain blood pressure, and treat other infections that often strike their weakened bodies. A small percentage of people appear to have an immunity to the Ebola virus.

Where does the disease come from?

Ebola was first discovered in 1976, and it was once thought to originate in gorillas, because human outbreaks began after people ate gorilla meat. But scientists have since ruled out that theory, partly because apes that become infected are even more likely to die than humans.

Scientists now believe that bats are the natural reservoir for the virus, and that apes and humans catch it from eating food that bats have drooled or defecated on, or by coming in contact with surfaces covered in infected bat droppings and then touching their eyes or mouths.

The current outbreak seems to have started in a village near Guéckédou, Guinea, where bat hunting is common, according to Doctors Without Borders.