The World Health Organization and the US Centers for Disease Control have both said the risk that Ebola will spread beyond West Africa is extremely low. "The virus is difficult to transmit," Gregory Härtl, a WHO spokesperson, told Vox. "Yes, there was this case of a person with Ebola going to Nigeria on a plane, but in all of history, only one or two people with Ebola got on planes."
Still, fear-mongering headlines about the worst outbreak in Ebola history abound in the press: "Here are the 35 countries one flight away from Ebola;" "Global authorities on alert over Ebola outbreak;" "Deadly foreign diseases are 'potential major threat'."
So we called Art Reingold, the head of epidemiology at UC Berkeley's School of Public Health to make sense of the news. As a disease epidemiologist who has spent the last 30 years studying the prevention and control of infectious diseases around the world, he knows how and why viruses spread. Here's a transcript of our conversation, lightly edited for clarity.
Julia Belluz: How is this outbreak different from others in the past?
Art Reingold: This outbreak is certainly really bad. It's different from the ones we have seen in the past, which generally have started in and often been confined to villages or reasonably limited areas where most of the population is rural and scattered. We now have an outbreak in multiple countries, including urban areas. For this outbreak to be in West Africa is unusual; most have been in Central and East Africa. This represents a new set of challenges people haven't faced before. It is definitely going to be a real challenge to bring this outbreak under control.
JB: Because this is the worst Ebola outbreak in history—with three Western African nations affected—and because Ebola is so deadly, people everywhere are afraid. What is the actual risk that this virus will spread beyond West Africa?
AR: People should not be concerned about Ebola spreading to the US or other wealthy countries. It's transmitted entirely through exposure to bodily fluids. In settings with Ebola, there's bleeding in a variety of places and the virus is present in those excretions, and people need to come into contact with that to get the virus. The people at risk are the family members who are taking care of sick people, those who are preparing bodies for burial, and health-care workers.
JB: Some airlines are enacting travel bans since the outbreak. Are they justified then?
AR: The virus is not transmitted through coughing and sneezing, or through sitting next to someone on a bus or the like. The idea that the virus can somehow mutate and become more readily transmissible from person to person through coughing or sneezing—those are Hollywood scenarios. The idea that Ebola can become more readily transmissible through casual contact is unrealistic and not something we are concerned about. It's people whose job it is to deal with this virus—those working at the ministries of health, health care providers, those struggling with how to get the outbreak in the affected countries under control—that need to be concerned.
JB: What about a worst-case scenario, if it did spread?
AR: In high-income countries like in Europe and the US, we know how to prevent the transmission of Ebola. It has to do with making sure suspected patients are treated and isolated, and appropriate measures are taken for the health-care workers taking care of them. That's what worked in Africa in the past and it should be possible to prevent further transmission of the virus. For people in the US, it's really not a plausible scenario that we are going to start to have to introduce these measures. I would have no fear or concern about getting on an airplane and going to affected countries if I had work to do there.
JB: Can you put the Ebola risk of death into the context of other diseases?
AR: A few thousand people in history have died of Ebola. Compared to AIDS or malaria or diarrhea, this affects far fewer people. More people die of diarrhea in a day than Ebola has killed in history.
JB: So if the risk is so remote, why do you think people are afraid?
AR: It's a highly lethal virus and sixty to seventy percent of the people who get it die. Being fearful is a reasonable response. But elevating that to a fear of getting Ebola by the average person is where it becomes irrational.