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Staff of Doctors Without Borders carry a body at a center for victims of the Ebola virus in Guéckédou, Guinea, on April 1, 2014.


Q&A: What's Behind Worst-Ever Ebola Outbreak in West Africa?

The disease has killed hundreds, prompting an emergency meeting of nations next week.

The deadliest-ever outbreak of Ebola is spreading rapidly through West Africa and has now infected 635 people, killing more than 60 percent of them so far.

The World Health Organization warned Thursday of the need for drastic action to contain the virus, and organized a meeting for next week with the ministers of health in Guinea, Liberia, Sierra Leone, and eight surrounding nations.

National Geographic talked with W. Ian Lipkin, an expert in viral diseases and the John Snow Professor of Epidemiology at the Mailman School of Public Health at Columbia University, about why this outbreak is so much more widespread than previous ones. (Related: "Why Is This Ebola Outbreak Spreading?")

Previous outbreaks of Ebola have been small and localized, but this one is much broader. Why the difference?

Typically, when we have an outbreak of Ebola, a team goes in, they identify the cases, they identify people who might come into contact with the cases. And as a result of isolation, we're able to contain the outbreak and it peters out fairly rapidly. Here, it's in urban areas as opposed to rural areas. There isn't enough manpower to track all these cases and make certain we educate people, and that's what's essential.

How contagious is Ebola?

This is not a highly transmissible disease, where the number of people who can be infected by a single individual is high. You have to come into very close contact with blood, organs, or bodily fluids of infected animals, including people. If you educate people properly and isolate those who are potentially infected, it should be something you can bring under control.

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Members of the Guinean Red Cross speak with a resident in Conakry during an awareness campaign on the Ebola virus on April 11, 2014.

Originally, this outbreak spread because of ritual burial practices that brought people into contact with fluids from dead bodies. Is that still a primary source of transmission?

It is an issue. With urbanization, you have people who are moving into urban areas who are not completely divorced from the practices they had in the rural areas. They're recent transplants and they carry with them that culture.

Is this one outbreak or have there been new introductions in the meantime?

Since the spring, it's just continued to spread. I can't tell you for certain there haven't been new point source introductions, but there seems to be no reason to think that.

What likely caused the initial infection?

What typically happens is somebody comes into contact with bush meat. Frequently, there's a harbinger of an outbreak. You [first] see deaths in great apes. When hunters handle infected chimpanzees, gorillas, or monkeys that are infected, they then become infected, chiefly through breaks in their skin or mucous membranes. They become the Trojan horse that carries the infected material back to the villages.

What does the Ebola virus do to the body?

It's a hemorrhagic fever virus. It causes an intensive inflammatory response. You wind up going into shock. You can't maintain your blood pressure. Ultimately, all your organs fail.

How long does it take to get sick once you're infected?

You may not show signs of disease for up to three weeks, but most people begin to show signs roughly a week after infection. Death comes within a few days to another week.

Is it possible to treat Ebola, to survive infection?

It's typically a lethal infection [with up to a 90 percent fatality rate]. People can recover, but it's not common. There are no treatments. The only thing we can do is try to maintain people's blood volumes by giving them fluids.

Are treatments under development?

There are people who are trying to develop antibodies from people who've recovered from infection and have antibodies that will neutralize the virus. And others [are] trying to work on drugs that may interfere with ability of the virus to reproduce itself.

Do we need to be concerned about Ebola spreading to the U.S. or other developed countries?

Is it possible that somebody could be infected in one of these countries and fly to the U.S.? It is certainly possible. Given our health care system, it's unlikely that we would have widespread disease as a result. We would be on top of it, and we would be able to contain it. Our health care system affords people access to gloves and gowns and personal protective equipment. I don't think there's reason for panic that we're going to be hit with an outbreak of Ebola.

With other pathogens, like the Middle Eastern Respiratory Virus (MERS), there's concern about the virus mutating and becoming more dangerous. Is that a concern with Ebola infections?

They kill so quickly that I don't envision there's going to be a major shift in transmission.

Do you think the West African countries are responding well to the crisis?

These are not wealthy countries. They don't have strong health care infrastructure. They need help. They don't have the resources to handle this. (Related: "Q&A: Challenges of Containing Ebola's Spread in West Africa.")