Little more than a year ago, around the time a 2-year-old boy in a village in Guinea was dying of a disease nobody there had seen, here is what most Americans knew about Ebola: It was found in remote areas of Central and East Africa, where it caused sporadic, deadly, but well-confined outbreaks. Its characteristic symptom was uncontrollable bleeding. There were no treatments, and it was fatal in the overwhelming majority of cases.
In light of that, it was unsurprising an outbreak in West Africa, spreading quickly from villages to large cities with air connections to the rest of the world, caused an international panic that led to quarantines as far away as Texas and Maine. But now, after nearly 7,600 deaths in three countries, and a handful in three others, including the United States, we know almost none of that is true. And we know a lot more as well, some of it reassuring and some sobering.
Here are some of the lessons of the outbreak: The most feared complication of Ebola infection, widespread hemorrhage, is actually somewhat uncommon. Most Americans were introduced to Ebola in Richard Preston’s 1994 book, The Hot Zone -- termed “one of the most horrifying things I’ve read in my whole life” by no less an authority than Stephen King.
Preston’s riveting account of a patient spurting blood from his mouth and rectum, dying in agony of shock and multiple organ failure, understandably stuck in the minds of readers.
The current outbreak, by far the largest ever, has clarified the clinical picture, so it now appears that widespread hemorrhage occurs in only a minority of infected patients -- around 18 percent to 25 percent, by the estimate of Derek Gatherer, a leading authority on Ebola at Lancaster University in Britain. But, he adds, “The ones who get it, are six to eight times more likely to die.”
It’s unclear why some patients do so much worse than others although in general, the disease strikes hardest in people older than 40. Patients who don’t proceed to hemorrhage typically die of other complications, including secondary infections or dehydration from prolonged, violent vomiting and diarrhea. “We’ve seen that this strain of Ebola has a lot more diarrhea than we thought, and less hemorrhagic symptoms,” said Dr. Jordan Tappero, director of the Division of Global Health Protection of the Centers for Disease Control and Prevention.
The sheer loss of fluid is staggering, as much as eight quarts a day, 10 percent of the body weight of a 160-pound man. And with the fluids go the electrolytes, dissolved minerals that regulate the heartbeat and other vital functions.
But fluid and electrolyte loss can be managed in a properly equipped hospital or clinic, which leads to another important lesson: Ebola can be treated. When the first of two nurses who contracted Ebola from a patient at Texas Presbyterian Hospital in Dallas recovered, it was treated by some in the media as a lucky fluke.
Then the second nurse got better even though the original patient -- who had contracted the disease in Liberia and was misdiagnosed at first by the hospital -- couldn’t be saved.
CDC figures indicate 10 patients have been treated for Ebola in U.S. hospitals, and all but two of them have recovered. The second fatality was a man who arrived from Sierra Leone at an advanced stage of the disease and died within three days.
Several of the survivors received experimental treatments, either the antiviral drug ZMapp or transfusions of blood plasma from recovered patients. But it’s not clear that made any difference. ZMapp has worked well in animal trials but hasn’t been tested in humans, and the few doses that were given out this year as a last-ditch measure had a mixed results. There were only a few doses available, and it was all gone by October. A new batch has been prepared and is being readied for clinical testing in humans early in 2015.
What does work for Ebola, at least in some cases, is basic supportive care to replace lost fluid, monitor and treat secondary infections, and deal with complications such as heart and kidney failure. Most of these are things that are, or could be, available in a reasonably well-equipped hospital anywhere in the world, but until the world ramped up its response to the current epidemic, most Ebola patients never saw the inside of a good hospital. Under current conditions, Gatherer says, “I would put your odds of surviving Ebola in a Western hospital as high as 90 percent. In an African field hospital, maybe 50 percent, and at home in Africa, 20 percent.”
In some ways, though, Ebola is even more dangerous than many people understood. The outbreak has reinforced the lesson that patients in the late stages of the illness, and their bodies after death, shed virus in extraordinary amounts through every pore and orifice. And the infectious dose is extremely small; in cultures, it takes only a single particle of Ebola to begin killing cells. As the Dallas experience showed, normal infection-control procedures are clearly inadequate. CDC protocols call for respirators and face shields, gowns, impermeable aprons, boots and double gloves -- and a trained observer to supervise the process of removing all that gear.
But, in an apparent paradox, the Dallas patient, Thomas Eric Duncan, lived with family members for several days after he became ill, and none of them caught Ebola. Nor did anyone who rode the subway with the American doctor who returned from Guinea to New York, and went to the hospital a few days later with what turned out to be Ebola. Nor those who flew from Cleveland to Dallas on the same plane with one of the Texas nurses, nor the other passengers on a plane with Patrick Sawyer, an American living in Liberia who flew from Monrovia to Lagos, Nigeria, when he was already showing symptoms of Ebola.
Sawyer, who was allowed to leave the country by mistake, started a chain of infection in Nigeria that led to eight deaths. But nobody caught it from him just by sitting in the same airplane. “Airborne transmission of Ebola virus has been hypothesized but not demonstrated in humans,” the CDC noted. In theory, Ebola could mutate in that direction, but scientists have seen no evidence of it happening. It would take a major mutation, and the virus has been quite stable in the roughly four decades since it was first recognized.
The “R number” for Ebola -- the number of new infections expected, on average, from each case -- has held fairly steady 2 and 2.5, roughly the same as influenza, about half that of SARS or smallpox and far below measles, with an R number as high as 18.
In retrospect, the wave of panic that spread from Dallas to most of the country last fall -- reaching its height when a Maine teacher was put on leave after she returned from Texas, not having come within 10 miles of the hospital where Duncan was being treated -- seems absurd. Responsible officials said so at the time, but some, such as the columnist George Will and Sens. Rand Paul, R-Ky., and Ted Cruz, R-Texas, may have stoked fears to make the administration look incompetent.
(Will opined that “a sneeze or some cough” could spread Ebola, and Paul said “political correctness” was leading authorities to downplay the threat. Cruz criticized the Obama White House for listening to "experts" instead of "commonsense" in refusing to institute a travel ban.)
So, outside West Africa, the world has mostly dodged this bullet. Gatherer estimated the R number for Ebola in the developed world would be around 1; if it dips below that, an epidemic cannot sustain itself. But the impact of the epidemic will be felt well beyond the three most-affected countries.
Nigeria, a much larger and richer country, contained its outbreak successfully, but it is also fighting a civil war; if an Ebola epidemic gets loose there, and in neighboring countries, the economic impact has been estimated by the World Bank at $32 billion. Peter Daszak, president of the EcoHealth Alliance, said that is on the order of the cost of the SARS epidemic in 2003, which caused many fewer deaths but affected a much richer part of the world. “China in particular is investing a lot in Central and West Africa,” Daszak said, “but it’s hard to sustain development if people are dying and nobody wants to go there.”
Even if the current Ebola outbreak is contained, he said, it should serve as a wake-up call to the world that emerging tropical diseases aren’t just a health issue, but one with big implications for economic development, the environment and agriculture.
Until this year, the world had never seen an urban epidemic of Ebola, and it has been a sobering lesson, Tappero said. “The number of potential exposures is so much bigger than in rural areas, and tracing the contacts is so much harder, because you come into contact with strangers. In Monrovia, in Freetown, we didn’t have enough tracing teams on the ground at first.” The lesson, he said, is to move fast at the first sign of an outbreak, a lesson CDC and other international health organizations have now learned, for the next epidemic.