A health worker sprays disinfectant on a colleague who had loaded a suspected Ebola victim into an ambulance in Freetown, Sierra Leone, on Sept. 24. (Michael Duff/Associated Press)

An idea long viewed as an unlikely possibility is now becoming increasingly real: Ebola might not go away for a very long time.

It has never happened before in the 38-year history of the virus. Every other time Ebola has made the unlikely jump from the animal world to the human one, it has been snuffed out within days, weeks or, at most, months.

This time, though, in Guinea, Sierra Leone and Liberia, the Ebola virus is raging like a forest fire, in the words of several public health officials. And some of them are raising the possibility that the outbreak-turned-full-fledged-epidemic could become fundamentally different from any other Ebola outbreak on record, in that it might stick around.

“What’s always worked before – contact tracing, isolation and quarantine – is not going to work, and it’s not working now,” said Daniel Lucey, a professor of Microbiology and Immunology at Georgetown University Medical Center, who spent three weeks treating Ebola patients in Sierra Leone and will soon travel to the Liberian capital of Monrovia for another five-week stint.

"In my opinion," Lucey added, "a year from now, we won't have one or two cases; we'll have many cases of Ebola."

As the worst Ebola outbreak in history unfolds in West Africa, The Post's Joel Achenbach explains how the deadly virus wreaks havoc on the human body. (Davin Coburn/The Washington Post)

Unlike past outbreaks, in which Ebola emerged in the sparsely populated countryside of Central Africa, this outbreak has become an exponentially spreading urban menace.

With the number of infected and dead in the thousands and growing quickly -- and the U.S. Centers for Disease Control and Prevention warning that it could surge past 1 million within four months -- finding and quarantining every person who might come into contact with the virus is a herculean task.

In cramped and chaotic large cities, Lucey said, it might be near impossible to adequately track Ebola infections without the help of medical interventions such as vaccines, anti-viral drugs or immune therapies, most of which could be months or more away from approval. "We would need a campaign like the global smallpox eradication program from the '60s and '70s," he said.

Even in the rural areas, there are worrying signs.

In some parts of West Africa, such as the rural area in southwestern Guinea near where the outbreak began, there are troubling indications that infections are continuing at relatively low but steady level from week-to-week.

That suggests a simmering, steady-state rate of transmission that is just as troubling as the exponential growth observed in the outbreak as a whole, according to Christopher Dye, the World Health Organization's director of strategy. In a new study he co-authored in the New England Journal of Medicine, Dye even raised the possibility that Ebola might become endemic in West Africa.

"The question we're raising is to put in people's minds that the epidemic might not be eliminated from the human population completely for a very long time," Dye said this week in an interview from Geneva. Unless global intervention begins to kick in soon, "at the moment we see no reason why that steady state will not continue to go on and on," he said.

A Liberian woman weeps over the Ebola death of a relative on the outskirts of Monrovia, the capital of Liberia. (Ahmed Jallanzo/European Pressphoto Agency) A Liberian woman weeps over the Ebola death of a relative on the outskirts of Monrovia, the capital of Liberia. (Ahmed Jallanzo/European Pressphoto Agency)

Epidemiologists consider a disease "endemic" if the transmission rate hovers around one per infection, and a region that's grappling with a constant low level of continued Ebola transmissions could find it impossible to resume normal public health operations.

In late August, when Lucey was in Sierra Leone, the country's only large referral hospital for children -- nicknamed Cottage Hospital -- shuttered its doors to keep Ebola out. A single child out of a steady stream of hundreds that passed through the facility on a regular basis had been treated for two days before anyone realized he had Ebola.

With Cottage Hospital closed, children and pregnant women in Sierra Leone have nowhere else to go to be treated for basic, life-saving medical care, Lucey said. In Liberia, the situation is similar: With Ebola crippling the health system, Liberians are dying of routine medical problems, as The Post reported last week.

That is how things are right now, with Ebola raging unabated.

But with this virus, there is no middle ground. The presence of even a small number of continued transmissions of Ebola can also wreak havoc on already fragile health-care systems.

When Ebola is present in the population, it is nearly impossible to know whether a patient who walks in is sick with the deadly virus rather than another of the many other conditions that can result in similar symptoms.

"So when a child has a fever and they spit up and they have some loose stools and diarrhea — that is very, very common in a child,” said Lucey. "How can you tell it’s not Ebola or something else? That means that the health-care providers have to wear this really comprehensive, hot, personal protective equipment for all of them."

Most public hospitals are closed because they do not have the ability to treat Ebola patients safely; the risk of treating non-Ebola conditions with similar symptoms – such as dengue fever or even diarrhea — is simply too great.

In Sierra Leone and Liberia, some of these concerns are already coming to pass.

Lassa fever – a similar, but less deadly hemorrhagic fever – is on the rise as the dry season begins.

"There's not even a place really to put all the Ebola patients, so now we're going to have to be thinking about how do we separate the lassa patients from the Ebola patients – because that is not something that we want to mix," Joseph Fair, a virus expert and special adviser to the health minister of Sierra Leone, said in testimony before Congress on Wednesday. "The chances of survival with lassa are much greater than with Ebola."

It is possible, however, that Ebola is not capable of enduring in the human population for long – in part because it is far too deadly. Daniel Bausch, an associate professor in the Department of Tropical Medicine at Tulane University, has spent years researching Ebola and other viruses at the CDC; he is an endemic Ebola skeptic.

"I actually don't buy it; I don't see how this disease could become endemic," Bausch said. "It would have to become much less deadly so you would have something where this can be maintained in a human population independently, long-term -- independently of its maintenance in the wild. You would have to have drastic mutations of the virus."

At least so far, there is no evidence that the virus has mutated significantly to make it any more or less deadly. According to Dye's WHO study of the first nine months of the outbreak, the mortality rate for the virus is 70 percent -- which is on par with previous outbreaks.

But whether Ebola becomes endemic or a just a very long, sustained epidemic that eventually ends, both outlooks are fairly grim.

"We'll either get a handle on it and stop transmission in those places, or we won't and the virus will rifle through the population," Bausch said. "Once it’s gone through population, then pretty much everybody gets Ebola and lives or dies."

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