As a rule, one should not panic at whatever crisis has momentarily fixed the attention of cable news producers. But the Ebola outbreak in West Africa, which has migrated to both Europe and America, may be the exception that proves the rule. There are at least six reasons that a controlled, informed panic might be in order.
(1) Start with what we know, and don’t know, about the virus. Officials from the Centers for Disease Control (CDC) and other government agencies claim that contracting Ebola is relatively difficult because the virus is only transmittable by direct contact with bodily fluids from an infected person who has become symptomatic. Which means that, in theory, you can’t get Ebola by riding in the elevator with someone who is carrying the virus, because Ebola is not airborne.
This sounds reassuring. Except that it might not be true. There are four strains of the Ebola virus that have caused outbreaks in human populations. According to the New England Journal of Medicine, the current outbreak (known as Guinean EBOV, because it originated in Meliandou, Guinea, in late November 2013) is a separate clade “in a sister relationship with other known EBOV strains.” Meaning that this Ebola is related to, but genetically distinct from, previous known strains, and thus may have distinct mechanisms of transmission.
Not everyone is convinced that this Ebola isn’t airborne. Last month, the University of Minnesota’s Center for Infectious Disease Research and Policy published an article arguing that the current Ebola has “unclear modes of transmission” and that “there is scientific and epidemiologic evidence that Ebola virus has the potential to be transmitted via infectious aerosol particles both near and at a distance from infected patients, which means that healthcare workers should be wearing respirators, not facemasks.”
And even if this Ebola isn’t airborne right now, it might become so in the future. Viruses mutate and evolve in the wild, and the population of infected Ebola carriers is now bigger than it has been at any point in history—meaning that the pool for potential mutations is larger than it has ever been. As Dr. Philip K. Russell, a virologist who oversaw Ebola research while heading the U.S. Army’s Medical Research and Development Command, explained to the Los Angeles Times last week,
I see the reasons to dampen down public fears. But scientifically, we’re in the middle of the first experiment of multiple, serial passages of Ebola virus in man. . . . God knows what this virus is going to look like. I don’t.
In August, Science magazine published a survey conducted by 58 medical professionals working in African epidemiology. They traced the origin and spread of the virus with remarkable precision—for instance, they discovered that it crossed the border from Guinea into Sierra Leone at the funeral of a “traditional healer” who had treated Ebola victims. In just the first six months of tracking the virus, the team identified more than 100 mutated forms of it.
Yet what’s really scary is how robust the already-established transmission mechanisms are. Have you ever wondered why Ebola protocols call for washing down infected surfaces with chlorine? Because the virus can survive for up to three weeks on a dry surface.
How robust is transmission? Look at the health care workers who have contracted it. When Nina Pham, the Dallas nurse who was part of the team caring for Liberian national Thomas Duncan, contracted Ebola, the CDC quickly blamed her for “breaching protocol.” But to the extent that we have effective protocols for shielding people from Ebola, they’re so complex that even trained professionals, who are keenly aware that their lives are on the line, can make mistakes.
By the by, that Science article written by 58 medical professionals tracing the emergence of Ebola—5 of them died from Ebola before it was published.
(2) General infection rates are terrifying, too. In epidemiology, you measure the “R0,” or “reproduction number” of a virus; that is, how many new infections each infected person causes. When R0 is greater than 1, the virus is spreading through a population. When it’s below 1, the contamination is receding. In September the World Health Organization’s Ebola Response Team estimated the R0 to be at 1.71 in Guinea and 2.02 in Sierra Leone. Since then, it seems to have risen so that the average in West Africa is about 2.0. In September the WHO estimated that by October 20, there would be 3,000 total cases in Guinea, Liberia, and Sierra Leone. As of October 7, the count was 8,376.