Inside the Fascinating and Terrifying Science of Ebola
By now, educated people in America know more about Ebola than they ever thought they would. While fearmongers have tried to terrorize the whole country into thinking it is on the verge of catching Ebola, cooler heads have largely prevailed. Bottom line, while Ebola is a devastating epidemic in Liberia, Guinea and Sierra Leone, most Americans are at virtually zero risk of getting it. The exception is truly heroic healthcare workers, like the two Dallas nurses who cared for Thomas Eric Duncan as he lay dying of the disease in Dallas, both of whom are now clear of the virus. And now there is Craig Spencer in New York, a physician with Doctors Without Borders who was infected while treating Ebola patients in Guinea.
In the October 27 issue of the New Yorker, Richard Preston delves deeply into the fascinating science behind the virus, and how genomics research may help to contain the outbreak. Preston asks Ebola researchers all the questions everyone wants to know; most notably, could the Ebola virus mutate and become airborne, and how far away is a vaccine or a cure?
Here are five fascinating tidbits from that investigation into the frontlines of Ebola research.
1. How infectious is Ebola?
In a fatal case, a droplet of blood the size of the “o” in this text could easily contain a hundred million particles of Ebola virus. Experiments suggest that if one particle of Ebola enters a person’s bloodstream it can cause a fatal infection.
Richard Preston explains that this could account for why many healthcare workers who contract Ebola cannot remember having made any specific mistake in protocol that would have exposed them. It also explains why the disease is so dangerous for healthcare workers and why even highly trained ones are at a high risk for getting the disease when they care for patients.
2. Is Ebola mutating?
Mutations, Preston explains, are errors in the genetic code that occur as a virus multiplies. As you read this and go about your business, the Ebola virus’ code is changing. Like any living thing, Ebola wants to survive.
So, yes, Ebola is mutating. The question is how.
“Ebola is not a thing but a swarm,” Preston writes. “It is a vast population of particles, different from one another, each particle competing with the others for a chance to get inside a cell and copy itself. The swarm’s genetic code shifts in response to the changing environment.”
3. Could Ebola become airborne?
As Preston explains, there are two ways for a virus to travel through air. One is inside a droplet (of sweat or mucus, or other bodily fluid).
Ebola is already traveling, and possibly infecting, people this way. The good news is that, because of gravity, it cannot travel very far in a droplet.
“The droplets travel only a few feet and soon fall to the ground,” Preston writes. “A rule of thumb among Ebola experts is that, if you are not wearing biohazard gear, you should stand at least six feet away from an Ebola patient, as a precaution against flying droplets.”
To really go airborne in the way that is far more worrisome, the Ebola virus would still be carried by the droplet of infected body fluid, but would have to remain alive once the droplet had dried out. It would then float through the air like dust, and in this drier state, be able to float longer distances, and be inhaled.
“Particles of measles virus can do this, and have been observed to travel half the length of an enclosed football stadium,” Preston writes, but thankfully, there’s no evidence that Ebola can.
So then the question is, could the virus mutate to a form where it could travel through the air dry—in other words, become airborne?
Scientists are fairly reassuring about this question. Preston spoke to Eric Lander, the head of the Broad Institute of MIT and Harvard, where the Ebola genome is being sequenced and tracked. “That’s like asking the question, ‘Can zebras become airborne,’" Lander told Preston. “That would be like saying that a virus that has evolved to have a certain lifestyle, spreading through direct contact, can evolve all of a sudden to have a totally different lifestyle, spreading in dried form through the air. A better question would be, ‘Can zebras learn to run faster?’ ”
What he means is, could Ebola evolve to be more contagious in ways that would not be as much of a change? One way it could, Lander told Preston, is by becoming less deadly in humans, killing a smaller percentage of them, but making them sick for longer.
“That might be good for Ebola, since the host would live longer and could start even more chains of infection,” Preston writes.
So, that’s a scary proposition.
4. Is ZMapp a cure for Ebola?
The New Yorker piece delves into the fascinating survival story of Kent Brantly, the American doctor who contracted Ebola and nearly died of it, before being brought back to Emory Hospital in Atlanta and being cured. Brantly was at death’s door when he was treated by an experimental serum called ZMapp. Before that, ZMapp had only been used on monkeys, but had shown promising results, bringing them back from being very close to death with three doses.
Brantly attributes his survival to the drug, but complete success cannot be claimed for it. A Spanish priest sick with Ebola was also treated with ZMapp and still died.
Another problem with ZMapp, which was developed in Canada, is that the world’s supply of it is now depleted.
According to Preston:
"More of the drug is growing in tobacco plants in a building in Kentucky. The plants have enough of the drug in them to make twenty to eighty treatment courses of ZMapp in the next two months, as long as there are no glitches in the process. The U.S. government and Mapp Biopharmaceutical are scrambling to get more plants growing, to increase production, but the scale-up will not be easy. The drug remains untested, and nobody can say whether it will ever become a weapon in the Ebola wars."
5. How far are we from developing a vaccine?
The New York Times reported the infuriating story Thursday that a vaccine was ready to be tested in humans 10 years ago. Had it gone forward, there could have been an Ebola vaccine in 2010 or 2011. But it went nowhere, because no one thought there was any money in it. Ebola outbreaks had been fairly limited, and only in poor countries.
With the fresh crisis, the research is amping up again. Preston estimates that a vaccine might be available as early as next year “for use on people who have already been exposed to Ebola, though it will still not be cleared for general use.”
There are many ifs, but let's hope.