Before this year, Ebola was a disease relegated to remote villages in Africa. Even public health officials didn't worry about it spreading very far. Until recently, they would probably tell you that the virus typically burned out after ravaging only a handful of people.

But then came 2014.

This year has, in many ways, rewritten the Ebola rulebook. We're in the middle of an unprecedented, nightmarish epidemic that has spread from a rural rainforest region in West Africa to large urban centers. We've seen the first-ever case of Ebola diagnosed in the US. The World Health Organization's director has called this epidemic "the greatest peacetime challenge" the world has ever faced, with the number of cases doubling each week.



Now, health care officials are starting to talk about a worst-case scenario for Ebola. The World Health Organization projects that 20,000 people will be infected in November. The Centers for Disease Control and Prevention, meanwhile, projects up to 1.4 million people could be infected by January, assuming that Ebola cases continue to increase exponentially (as they have) and are currently underreported.

This worst-case scenario could become a reality, experts say, if the situation in West Africa continues to deteriorate. Here are five reasons why:

1) The best methods we have to contain Ebola are failing

Public health officials are terrified that one of the cornerstones of an Ebola response — tracing the contacts of those infected — can't keep pace with the epidemic.

Tracing the contacts of those infected has become increasingly difficult

In the past, trusty volunteers and public-health workers would follow all the people who had come into contact with an Ebola patient for 21 days (the virus' incubation period) to make sure that those people didn't develop any of the early flu-like symptoms of the disease. If anyone did, they would be put in quarantine to be monitored further and to ensure they didn't give the virus to anyone else.

This method worked extremely well. It helped to curb every previous known Ebola outbreak in history — and it even seems to have worked in the small outbreaks this year in Senegal and Nigeria, which have just reported zero suspected cases.

But in Liberia, Sierra Leone, and Guinea, which each have thousands of infected people, contact tracing becomes impossible. Consider this: the WHO estimates that every person in this region has at least ten contacts. Liberia already has over 3,000 cases of Ebola. That would be 30,000 potential contacts to follow-up. Imagine, if by the year's end, we see nearly 300,000 cases.

So the best method to curtail this untreatable disease is useless at the scale of the outbreak before us. And this keeps health professionals familiar with the disease up at night.

2) We may not get the health workers we desperately need

One unique and terrible feature of the epidemic is the fact that doctors, nurses, and hospital staff are getting infected and dying at an unprecedented rate. The WHO has reported, as of September 22, that 384 health-care workers have gotten the virus and 186 have died.

The WHO says it needs a 20-fold increase in health personnel

The WHO has said it needs a 20-fold increase in health personnel (20,000 national staff and 1,000 internationals) and President Obama has promised to train 500 health workers per week to work to beat back the epidemic.

But in the current environment, it's difficult to both recruit and retain the exact health-care professionals needed to treat Ebola patients. And officials worry that doctors simply won't show up.

"One of the things that is not always that well understood is just how difficult it is to find the labor to do this work in West Africa, both nationally as well as the expats," said Daniel Bausch, associate professor at the Tulane University School of Public Health and one of the Ebola experts training American staff to go to West Africa. In Liberia, for example, the medical school was closed during its civil war from 1999 to 2003, so the country was not graduating medical doctors, he said.

Much of the challenge has come from keeping local workers on the job. Ebola outbreaks don't typically happen in West Africa, and that meant doctors and nurses weren't prepared for what treatment would entail. Even after they learned about Ebola, they didn't have the resources (gloves, gowns, masks and personnel) to stay safe. Some have walked off the job because the stress and danger of caring for people in a drastically under-resourced setting became overwhelming.

The populations affected also had no experience with this nightmarish disease. Suddenly, they saw health workers coming into their communities — including foreign aid workers — spreading word about an almost unbelievably violent virus and taking their relatives away to containment facilities, sometimes never to be seen again.

"you go to West Africa, and you say, 'Raise your hand if you want to work in an Ebola treatment unit.' You don't see many hands in the air."

This environment bred a disturbing reaction. There is, understandably, fear everywhere. There is denial. But worst of all, there have been reports of sporadic violence: West Africans stoning, beating, and even killing health workers, both national and international, who are simply there to help.

People on the ground aren't optimistic that the needs and promises about health personnel will materialize.

"In the last six months, a fair number of doctors have been infected and killed by the Ebola virus," said Bausch. "Obviously if you're one who hasn't been infected with Ebola, how enthusiastic are you about doing that work if you see colleagues getting sick and dying? So you go to West Africa, and you say, 'Raise your hand if you want to work in an Ebola treatment unit.' You don't see many hands in the air."

That's not to mention the difficulty of identifying and training international workers who are willing to go to West Africa amid the violence and underfunding that some have been met with. So even if more hospital beds and care facilities are erected in the coming months, as President Obama has planned, without the doctors, nurses and cleaners to staff them, they won't be of much help.

3) West Africa's fragile economies are falling apart

Before the Ebola outbreak began, some of the Western Africa nations it hit hardest were seeing promising signs of economic growth. Sierra Leone, for example had the second highest real GDP growth rate. Liberia was 11th in 2013. The US, by comparison, ranked 157.



Ebola has led to widespread food insecurity Now, there's worry that the Ebola outbreak will slam the brakes on that development.

"A prolonged outbreak could undercut the growth that these countries were finally starting to experience, taking away the resources that would be necessary for improving the health and education systems," says Jeremy Youde, a professor of political science at the University of Minnesota Duluth.

"These countries are generally not starting from a great position as it is, so they don't have much of a cushion to absorb long-term economic losses. If the international economy turns away from West Africa and brands it as diseased, that could be very problematic."



Last week, the World Bank said Ebola may deal a "potentially catastrophic blow" to the West African countries reeling with the virus. Businesses are shutting down, people aren't working, kids aren't going to school.

There's widespread food insecurity. "The fertile fields of Lofa County, once Liberia's breadbasket, are now fallow. In that county alone, nearly 170 farmers and their family members have died from Ebola," the WHO director warned. "In some areas, hunger has become an even greater concern than the virus."

So, as the epidemic continues, these countries become further destabilized and their fragile economies, broken. People die not just of Ebola but of all of its social side-effects.

4) People are dying in record numbers from other diseases

Before the Ebola outbreak, the three countries most affected had very weak health systems and little money to spend on health care. Less than $100 is invested per person per year on health in most of West Africa. These countries record some of the worst maternal and child mortality rates on the planet.

'The whole general health system is collapsing'

Ebola is depleting those already scarce supplies. Hospitals and clinics have shut down since the outbreak, so people don't have access to the usual maternity or malaria care they need. The ones that are still open are reportedly overwhelmed with Ebola patients.



"The whole general health system is collapsing," Jimmy Whitworth, the head of population health at Britain's Wellcome Trust, told the Independent in an interview. If they do still have access to care, he added, "People aren't going to hospitals or clinics because they're frightened, there aren't any medical or nursing staff available."



"West Africa will see much more suffering and many more deaths during childbirth and from malaria, tuberculosis, HIV-AIDS, enteric and respiratory illnesses, diabetes, cancer, cardiovascular disease, and mental health during and after the Ebola epidemic," wrote disease researchers Jeremy Farrar, of the Wellcome Trust, and Peter Piot, of the London School of Hygiene and Tropical Medicine in a new article in the New England Journal of Medicine.



This outbreak will have lasting effects on health care for West Africa. Dr. Ezie Patrick, based in Nigeria with the World Medical Association, told Vox that the ratio of doctors per population is about 1: 6,000 in some places. "This shows the gross inadequacy of doctors," he said. "Sadly Ebola is claiming the lives of the few doctors who have decided to work in these challenging health systems thereby worsening the dearth and also increasing the brain drain leading to far fewer doctors in the region."

5) Violence and terror escalates, isolating a region



Until this epidemic is stopped, all countries will need to be on alert for Ebola victims: airport staff outside of West Africa may need to start screening for Ebola, hospitals are already arming themselves with equipment and training their staff to deal with the disease, and people everywhere will learn to fear this deadly virus.

But the impact of a long-running epidemic will be felt the most in West Africa, where there's some debate about whether Ebola could become a permanent fixture.



For now, Bausch and others worry that the denial and fear about Ebola could spread further, ripping apart the social fabric of West Africa and isolating the region from the world. As Piot and Farrer wrote in the New England Journal, it's not the biology or mutations of the disease that are causing the devastation; it's social factors: "... the combination of dysfunctional health systems, international indifference, high population mobility, local customs, densely populated capitals, and lack of trust in authorities after years of armed conflict."

"That these communities that have been resistant (to aid) means they are clearly in denial, violent denial," Bausch observed. "I would fear a much more unhealthy social adaptation: that the violence against the international community would become so ferocious, like with the death of the people in Guinea a few days ago, that none of us (health workers) are understandably going to risk our lives (to work there)."

The side effect of the fear is that not only isolating and ostracizing people with Ebola, but an entire block of countries. "With that horrific social adaptation, in the process you have the society that further breaks down: people not getting treated for malaria, people dying of starvation, all the trade routes (cut off), commercial processes break down. I hope we don't see it. It's the worst-case scenario."

Is there reason for hope?

Right now, there's some reason for hope. Most of the projections about cases escalating to the hundreds of thousands or millions are based on all the interventions we have put in place failing. As the CDC's director Tom Freiden said, this is a "fluid and dynamic situation. What the modelling shows us is even in dire scenarios, if we move fast enough we can turn it around."



Hopefully, the unprecedented response by the global community — the UN resolution, the personnel the US, Cuba, England and other countries are sending over — will get there fast enough to make a difference. As Frieden said, "The surge now can break the back of the epidemic. But delay is extremely costly in terms of lives and effort."

It appears Senegal and Nigeria battled back the virus through contact tracing and isolating cases. Though they only had a few cases and deaths each — tiny outbreaks compared to the scale in the other affected countries — they show that with the world on alert, when the disease turns up elsewhere, health officials can still mount successful responses. The worst-case scenario is, in other words, avoidable.