Photograph by Tyler Hicks, Hulton Archive/Getty

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A nurse wears protective clothing in the Ebola isolation ward of St. Mary's Hospital in Lacor, Uganda, in February 2001. He wrote the messages on his face shield after surviving the virus himself.

Photograph by Tyler Hicks, Hulton Archive/Getty

Why Is This Ebola Outbreak Spreading?

The deadly virus emerged in Guinea and spread to Liberia and Sierra Leone. Can it be stopped?

At least 60 people have died from an outbreak of the Ebola virus in Guinea. This particular outbreak has moved from the jungle to Guinea's capital city, Conakry, and reportedly crossed into Liberia and Sierra Leone.

The virus is transmitted by blood or other body fluids. Victims bleed internally and externally. The fatality rate can reach 90 percent, according to the World Health Organization. To learn more, we spoke to Ian Lipkin, the John Snow Professor of Epidemiology at Columbia University's Mailman School of Public Health in New York City.

How do humans contract this virus?

The original source is likely to be an affected animal—a bat or sometimes a primate. In the preface to human outbreaks, we see the loss of gorillas and other great apes in the vicinity where people become ill. We haven't heard anything of that sort [regarding the loss of primates in this outbreak]. (Related: "Ebola in Uganda: Why Can't We Cure It? Where Does It Hide?")

What causes the virus to move from animals to people?

The initial infection is through bush meat. If there are infected bats—or primates used as protein—in the process of butchering them, a person gets in contact with blood.

How does it move from person to person?

It's not easily transmitted. But there's this ritual behavior [in some areas, where] they wash bodies by hand to prepare for burial—a loving way of sending the spirit into the next world. This kind of behavior brings people into very close contact with body fluids that are infected, and that's how people become infected.

Typically these outbreaks are relatively easy to control if you can get people to stop washing dead bodies.

What about sexual contact?

There's some evidence of sexual spread, but I don't think that's a major issue. The major way it's spread is by butchering of infected animals and ritual funeral practices.

In this case, the virus seems to be moving—from rural regions into Guinea's capital, and across borders.

That's a little bit unusual and suggests a human carrier. These outbreaks typically occur in jungles or rural areas where people come in contact with bush meat.

It will be interesting as we do the postmortem [on the Guinea outbreak] to figure out how it crossed borders. It suggests to me probably [the transportation of] a dead body was involved. When an individual dies in a given area, if his relatives take care of him or her in that location, it doesn't spread any further. If they decide they want to move the body to bury it someplace else or somebody who lives in the city goes out to the country and takes care of someone and returns to the city, they may bring the infection with them.

Is Ebola always fatal?

There are cases where people survive, but it's an extremely dangerous infection. The majority of people who show signs of infection die.

Can the disease be treated?

We don't really have any good drugs. People are working on this.

Would a vaccine work?

The thing about vaccines is you don't generally vaccinate people for something that doesn't occur commonly. Even if you have a vaccine that is effective, there's always a potential risk associated with using vaccines. What may make more sense is to bring [treatment] online when people have been infected. There's a lot of emphasis on therapeutic antibodies from people who've survived infection, which could create instant immunization, or drugs that can prevent the virus from replicating. There's nothing on the market as yet. But in some of the animal models, people have infected the animals and then vaccinated them and achieved protection.

Will this new outbreak be contained at some point?

What normally happens is that international groups like Médecins Sans Frontières come in and cordon off the area, use a variety of diagnostic tests to exclude the worried well from truly sick, and try to interfere with some of these funeral practices. Then the episode dies out. But [this outbreak] seems to have moved. It's not as well contained as we would have hoped. I anticipate we will lose many people, but it will be a self-limited outbreak. We've lost less than 70 people. But it's terrible.