TOPICS > Science > cracking ebola's code

Using the power of prediction to halt Ebola in its tracks

June 11, 2015 at 6:20 PM EDT
The Ebola outbreak in West Africa has claimed more than 11,000 lives. But it could have been worse if it wasn’t for sophisticated prediction models. In the third installment in our series Cracking Ebola's Code, science correspondent Miles O’Brien discovers how these models can help decelerate the expansion of the deadly virus.

JUDY WOODRUFF: Now to our special series on stopping Ebola.

The worst of the epidemic has passed, but, recently, there has been a small uptick in cases in West Africa. More than 11,000 people died since the outbreak began; 27,000 were infected over the past year. At its height, experts warned the death toll could climb much higher if certain actions were not taken.

How experts went about doing that is the focus of our piece from science correspondent Miles O’Brien, part of his series Cracking Ebola’s Code, showcasing research and innovation to help treat Ebola or prevent its spread.

MILES O’BRIEN: Ever since Ebola came to Sierra Leone, the traditional Sunday morning run near the beach in Freetown has moved to an urgent cadence.

But the double-time march to end the Ebola crisis is not over. The virus, and the finish line, remain moving targets. And an army of public health workers in command centers here and all around the globe are employing sophisticated modeling technology in new ways to track the trajectory of the epidemic.

DR. THOMAS FRIEDEN, Director, Centers for Disease Control and Prevention: We still have a long, hard road to get to zero. Getting to zero means finding every case of Ebola, every contact, and making sure people are rapidly isolated.

MILES O’BRIEN: Tom Frieden is the director of the Centers for Disease Control and Prevention. He says they would be nowhere near zero if it wasn’t for the power of sophisticated predictions.

DR. THOMAS FRIEDEN: Getting a rapid, robust response in West Africa was incredibly important. The model projected what would happen if we didn’t do that, and providing that information was quite important in galvanizing the energy and progress that we have seen.

MILES O’BRIEN: At an Ebola treatment center run by the International Medical Corps in Kambia, Sierra Leone, it’s time for the shift change briefing.

WOMAN: The patient is in critical condition. He needs a close monitoring when you enter. He has the redness of the eyes, and there’s bleeding from the nose.

MILES O’BRIEN: There are eight patients here, most at death’s doorstep.

Dr. Kashif Islam Siddiqui is one of the physicians taking great risks to treat Ebola patients while they are most contagious.

DR. KASHIF ISLAM SIDDIQUI, International Medical Corps: Although all of them are at the stage where the symptoms are maximum, but still we are hopeful that most of them will make it.

MILES O’BRIEN: It may be the endgame, but it is no time to relax.

DR. PAUL ARMSTRONG, World Health Organization: In the tail end of the epidemic curve, we have had a very bumpy time. So, sometimes, we have several cases per week, and other times we might have one or, in some districts, quite a few districts, it’s zero.

MILES O’BRIEN: Dr. Paul Armstrong is a field coordinator for the World Health Organization. His job here is made more complex by geography.

We are only three miles from the Guinean border. On the other side, there’s a duplicate team making their own plans in a different language. And while there are checkpoints with infrared cameras at the main roads, the border is completely porous most everywhere else.

DR. PAUL ARMSTRONG: So, whenever we have a case, we must work out who are the close contacts of that person who also might be harboring the infection? And if they cross the border, then we must tell our counterparts over there. And because they speak French and we speak English, that adds quite a complexity to it.

MILES O’BRIEN: Meanwhile, 4,800 miles away, at CDC headquarters in Atlanta, they are watching it all unfold, monitoring globally, but acting locally.

DR. THOMAS FRIEDEN: This is the nerve center where we track what’s happening, both the epidemic, the response to the epidemic.

MILES O’BRIEN: But who and what to send, and where? And what is job one? Frieden admits he had a hard time answering those questions. There was no playbook for this.

DR. THOMAS FRIEDEN: One of the tremendous challenges with the Ebola epidemic from August and September was that it was a fog of war situation. We didn’t have a clear sense of what was really happening with the epidemic.

MARTIN MELTZER, Centers for Disease Control and Prevention: Particularly, as you know, we’re now going to face even more questions about those lines that go up.

MILES O’BRIEN: So, he turned to this man. Martin Meltzer is a senior health economist who heads the modeling team at the CDC.

MARTIN MELTZER: We don’t make up the answer that will make all the decisions for them. We produce some numbers that help them come to a decision.

MILES O’BRIEN: They formulated a model designed to predict how bad things might get. They factored in things like how many cases there are, how long people stay sick, how likely they are to survive, how many will seek care, and how many are accurately diagnosed.

Although there’s a lot of complicated mathematics beneath what you see on the screen, the result is a simple spreadsheet that is shared publicly. Meltzer believes in transparency.

MARTIN MELTZER: These people here, in the red, are where you don’t want your patients to be. They are at home. They’re not isolated. There are still connection and contact with the family and the rest of the community, and there is no safe burial.

MILES O’BRIEN: When Meltzer and his team first ran the numbers, the results took their breath away. The line quickly went off the charts, an exponential train wreck, 1.4 million confirmed Ebola cases predicted in a few months if assistance wasn’t mobilized immediately.

MARTIN MELTZER: Every month of delay more than doubled the number of cases that might occur because of that delay. So, the model ultimately showed, not only the problem, but the need to solve it by going big and going fast.

DR. THOMAS FRIEDEN: And you double and you double and you double. And if you don’t break the back of exponential growth, you get into a situation that’s even more horrific than what we saw.

MILES O’BRIEN: Other disease modelers were equally alarmed. At Northeastern University, Alessandro Vespignani also created an Ebola epidemic model at his Laboratory for the Modeling of Biological and Socio-Technical Systems. It predicted that, if nothing was done, Ebola would spread way beyond West Africa.

ALESSANDRO VESPIGNANI, Northeastern University: And you will see that, by February, already, you get Africa that is in a very bad situation, but then you start to have places which have serious outbreaks in various places in Europe.

MILES O’BRIEN: Paris, London and New York would have all been coping with serious Ebola outbreaks.

ALESSANDRO VESPIGNANI: This is something that would be really a worst-case scenario. So that would be something that you don’t even want to think about it.

MILES O’BRIEN: Wow. That’s many millions of people afflicted, right?

ALESSANDRO VESPIGNANI: That would be obviously something that of — well, unthinkable.

MILES O’BRIEN: But the CDC makes no apology for sharing the worst-case scenario.

MARTIN MELTZER: I don’t think of terms of scaring or not scaring people. I look at the numbers. I look at them and say, is this a fair representation of what we know at that time?

MILES O’BRIEN: The trickier part was how to respond. The models made it frighteningly clear there was no earthly way to build Ebola treatment centers fast enough to answer the crushing need for isolation care.

So the only way to stop the epidemic was to change human behavior. Public health professionals had to educate people to routinely wash their hands, stop embracing each other, and, most important, refrain from the ritual washing of the dead. If all of this could happen, the model yielded some good news.

DR. THOMAS FRIEDEN: If you got to 70 percent safe burial, safe treatment, you got to a tipping point. And that was really important. That gave us a goal. And then, surprisingly, it showed that, if you did that, it would also come down exponentially as well.

MILES O’BRIEN: In Freetown, Sierra Leone, public health officials, already under siege, were stunned by the grim outlook.

Dr. Mohamed Samai is provost of the College of Medicine and Allied Health Sciences.

DR. MOHAMED SAMAI, College of Medicine and Allied Health Sciences. Well, initially, the first thing is denial. You may — you may just say, it’s impossible. But then, looking at the cultural beliefs of our people, then you will be tempted to believe that that projection will definitely come to pass.

MILES O’BRIEN: In the isolated villages of West Africa, many believe in witchcraft and home remedies. Some are convinced Ebola is a plot by white people, if it exists at all.

Vandy Kamara does outreach for the International Medical Corps.

VANDY KAMARA, International Medical Corps: A lot of the chiefdoms, a lot of the people that we meet in the chiefdoms simply have been challenging us, that Ebola is not real, that it’s just something that was made up, and, yes, they are still in denial.

MILES O’BRIEN: But the grim reality of the epidemic, coupled with an intense public outreach effort, eventually turn the tide. Safe burial practices became common, and people in the densely populated cities of West Africa changed the way they interacted with each other. The predictions of millions of Ebola cases didn’t pan out.

ALESSANDRO VESPIGNANI: We don’t want to be right. I don’t want to have millions of people dying. What we want to say is, look, this is going to happen if we don’t do something.

MILES O’BRIEN: Today, there are hundreds of surplus isolation beds in temporary structures like these all throughout West Africa. Built by the U.S. and other Western nations, they were too late. Fortunately, they are too much, for now. But when modelers run the numbers on the people and the diseases that intersect in this part of the world, they are certain another exponential threat lies ahead.

Miles O’Brien, the PBS NewsHour, Freetown, Sierra Leone.