Until this epidemic, the virus, which kills up to 90 percent of those who fall ill, had struck mainly in small, rural villages. But this outbreak has covered a much broader area—and has killed more than 670 people since late last year. It has now spread to Lagos, and reports came in over the weekend that it had killed a Liberian doctor and sickened two American medical workers, who fell ill after treating patients in Liberia. Both workers are still being treated, and it's not yet clear whether they'll survive.
Public health experts say they expect the virus to reach other parts of the world, including the United States, though it's unlikely to spread widely in regions with well-funded hospitals and standard infection-control procedures. (Related "Why Is This Ebola Outbreak Spreading?")
National Geographic recently 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.
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.
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.
Kumba Conde cries as members of the Red Cross arrive in Koundony, Guinea, with the body of her sister, Marie, 14, who died after she became infected with the Ebola virus.
PHOTOGRAPH BY SAMUEL ARANDA, THE NEW YORK TIMES/REDUX
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.