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This Mathematical Model from 2006 Shows How Ebola Could Wipe Us Out

The complex systems theorist whose model predicted the Arab Spring has some grim predictions about the Ebola outbreak.
September 4, 2014, 7:50pm
Image: NECSI

The current Ebola outbreak in West Africa is the worst in history, and the death toll just surpassed 1,900. Previous WHO estimates indicated that the outbreak would end mid-fall, but the situation is quickly spiraling out of control and into a sea of unknowns.

The "Ebola epidemic is the largest, and most severe, and most complex we have ever seen in the nearly 40-year history of this disease," World Health Organization director general Margaret Chan said in a special briefing yesterday. "No one, even outbreak responders, [has] ever seen anything like it."


Yaneer Bar-Yam, the complex systems analyst whose model accurately predicted the global unrest that led to the Arab Spring, is also worried about the patterns he sees in the disease's advance. Models he designed for the New England Complex Systems Institute back in 2006 show that Ebola could rapidly spread, and, in a worse case scenario, even cause an extinction event, if enough infected people make it through an international airport.

"What happened was that we were modelling the dynamics of the evolution of diseases—of pathogens—and we showed that if you just add a very small amount of long-range transportation, the diseases escape their local context and eventually drive everything to extinction," Bar-Yam told Motherboard. "They drive their hosts to extinction."

'A cascade of infection starting in Africa'/NECSI

Bar-Yam says he has informed the WHO and the CDC of his findings, but they haven't listened, he said.

"I just gave a lecture to the World Health Organization in January and I told them. I said, there's this transition to extinction and we don't know when it's going to happen," Bar-Yam explained. "But I don't think that there has been a sufficient response."

Normally, the spread of a predator—and this is as true for Ebola as it is for invasive animal species—is stymied when it overexploits its prey, effectively drying up its own food source. In rural areas like those where the current Ebola outbreak is centered, diseases tend to contain themselves by wiping out all available hosts in a concentrated area.


If a particularly aggressive predator happens to make it out of its local context, say, on an international flight, Bar-Yam's models show that it can avoid local extinction through long-range dispersal. At this point, the linear model of the disease's outbreak makes a statistical transition into an entirely different dynamic; extinction for all of its hosts across vast geographic distances, and only afterwards for the disease.

The argument has been made that an Ebola outbreak would not be as severe in the West as it is in Africa, because the poor healthcare infrastructure where the disease has struck is the chief vector of its spread. Bar-Yam sees this assumption as a vast overestimation of our handle on the dynamics of disease containment.

The question becomes, at what point do we hit the panic button? What does it look like to hit the panic button?

"The behavior of an individual in a major metropolitan area in terms of engaging with the health care system depends on a lot of different factors," Bar-Yam explained. "A reasonable person might be have in one way, but another person will behave in another. We don't know what happens if someone with Ebola throws up in a subway before that gets cleaned up and people understand that happened because of Ebola."

Panic is never a wise thing to incite, because it can result in exactly the kinds of unpredictable behavior that Bar-Yam is warning us about. However, a healthy amount of fear is a different matter.


"The question becomes, at what point do we hit the panic button? What does it look like to hit the panic button?" he said.

Bar-Yam's suggested approach to containing the outbreak is radical, he admits, and flies in the face of the WHO's nonplussed reaction to Korean Airlines, which stopped running flights into Kenya last week. According to the WHO, halting flights to West Africa makes it difficult for healthcare experts to make it into the region to help. Bar-Yam agrees, but maintains that the danger of the disease coming back with them is too great a risk.

"They're saying they need a large number of healthcare professionals to go there and deal with this. But that doesn't mean that people have to leave there," he said. "One sets up a one-way transportation system where people can go there to deal with the disease."

It's a prescription that is likely to bristle healthcare experts who'd to help Africans suffering from Ebola without necessarily signing their own death certificate. However, Bar-Yam said, the possibility of Ebola making it into a metropolitan area is far more grim than any potential containment efforts.

While the outbreak response thus far has been more or less handled on an individual basis, treating cases as they pop up while simultaneously studying the infection, a containment attempt to limit movement in and around the diseased area is a systemic response, and that's exactly what's needed.

"If the disease comes to an urban area in the United States, the targeted response of addressing individuals who have the infection is not the same as a systemic response that addresses the ability of the disease to spread," Bar-Yam said. "We need to have the knowledge and understanding of how to do a systemic response."