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Ebola has up to an 18% chance of coming to America. Here's why you don't need to panic.

Workers unload Ebola relief aid from a cargo flight organized by the United Nations Children's Fund in Harbel, Liberia.
Workers unload Ebola relief aid from a cargo flight organized by the United Nations Children's Fund in Harbel, Liberia.
John Moore

There's a new study about Ebola spreading beyond West Africa, and it seems alarming.

But before you read ahead, please keep this perspective: although Ebola is a brutal nightmare of a disease, and the media have rightly been paying a lot of attention to this epidemic (the worst in history), it's extremely rare, even among causes of death in Africa where Ebola usually strikes. HIV/AIDS, malaria, and diarrhea kill millions of people in Africa every year; Ebola has killed a couple thousand since 1976, when it was discovered.

The chances of a case in the developing world turning into an outbreak are also remote. That's because we know how to stop Ebola and have the tools necessary to do so. Many of these tools are sadly missing in African's under-funded health systems and have therefore created an environment in which the epidemic has spun out of control.

With those caveats in mind, let's look at the new data.

Where will Ebola fly to?

In epidemic or pandemic situations, travelers are the most likely method of transport for a disease. So infectious diseases researchers looked at flight patterns out of West Africa and local transmission dynamics to figure out how likely it would be that an Ebola-positive person gets on a plane with the virus and brings it to a new setting.


(Graphic courtesy of PLoS Currents: Outbreaks.)

In a Sept. 2 article in the journal PLoS Currents: Oubtreaks, they published their findings. "Results indicate that the short-term (3 and 6 weeks) probability of international spread outside the African region is small, but not negligible," they wrote.

Ghana, the United Kingdom, Gambia, the Ivory Coast, and Belgium were the countries most at-risk of importing at least one case by Sept. 22, the date they chose as the projected cut-off for their model.

Out of the 16 countries analyzed, the US ranked 13th (toward the last) for risk of importing Ebola by that time. The risk for the US was as high as 18 percent and as low as one percent.

Still, they wrote, "The extension of the outbreak is more likely occurring in African countries, increasing the risk of international dissemination on a longer time scale." In other words, again, it's still Africa most at immediate risk for bearing the burden of this terrible disease. But if the epidemic continues to grow in Africa over the coming the months, that risk of Ebola mutating and going global could grow, too.

Obama calls Ebola "national security priority"

For these reasons, President Barack Obama has called Ebola a "national security priority," according to Time magazine. On NBC's Meet the Press this Sunday, he said, "Americans shouldn't be concerned about the prospects of contagion here in the United States short term, because it's not an airborne disease."

But, he added: "If we don't make that effort now, and this spreads not just through Africa but other parts of the world, there's the prospect then that the virus mutates." At that point, "it could be a serious danger to the United States."

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