In early 2014, the largest-ever Ebola outbreak started up in Guinea and eventually spread to eight other countries by the following year. It challenged West Africa — and the global health order. Here's what you need to know.

The 2014 Ebola outbreak was worse than all other Ebola outbreaks combined

The Ebola virus is a hemorrhagic fever that kills about 70 percent of its victims. Ebola typically strikes like the worst and most humiliating flu you could imagine. People get the sweats, along with body aches and pains. Then they start vomiting and having uncontrollable diarrhea. They experience dehydration. These symptoms can appear anywhere between two and 21 days after exposure to the virus. Sometimes patients go into shock. Rarely, they bleed.

In fatal cases, death comes fairly quickly — within a few days or a couple of weeks of getting sick. Survivors return to a normal life after a monthslong recovery that can include periods of hair loss, hearing loss and other sensory changes, weakness, extreme fatigue, headaches, and eye and liver inflammation. In a phenomenon now dubbed "post-Ebola syndrome," Ebola, scientists have learned, can continue to live in other parts of the body or bodily fluids, including the eyeballs or semen of survivors, for months after the blood is declared virus-free.



There are five species of Ebola, four of which have caused the disease in humans: Zaire, Sudan, Taï Forest, and Bundibugyo. The fifth, Reston, was discovered in Virginia and has infected only monkeys. The animal host of Ebola is widely believed to be the fruit bat, although scientists haven't been able to confirm this. The virus only seldom makes the leap into humans.



The current outbreak involves the Zaire strain, which was discovered in 1976 — the year Ebola was first identified in what was then Zaire (now the Democratic Republic of the Congo). That same year, the virus was also discovered in South Sudan.



The Ebola virus is extremely rare. Compared with the leading causes of death in Africa, Ebola only accounts for a tiny fraction of deaths. People are much more likely to die from AIDS, respiratory infections, or diarrhea, as you can see.

Since 1976, there have only been about 20 known Ebola outbreaks. Until last year, the total impact of these outbreaks included 2,357 cases and 1,548 deaths, according to the Centers for Disease Control and Prevention. These cases almost uniformly occurred in isolated or remote areas of Africa, so Ebola never had a chance to go very far.



And that's what makes the 2014-'15 outbreak so remarkable: since the first patient was identified in January 2014, the virus has spread to nine countries, including the US (plus a separate outbreak in the Democratic Republic of the Congo) and has already infected more than 25,000 people. It has killed more than 11,000. That is more than seven times the death toll of all previous outbreaks combined, making this epidemic one of the worst public health crises of the last century.

Here's how you can catch Ebola — and how you can't

To get Ebola, you need to have direct contact with the bodily fluids — such as vomit, urine, or blood — of someone who is already sick and has symptoms.



But what, exactly, does that mean? Here's a more concrete guide on how the virus can move from one person to another.

How you can get Ebola

1) You can get the virus if you have "direct contact" with a range of bodily fluids from a sick person, including blood, saliva, breast milk, stool, sweat, semen, tears, vomit, and urine. "Direct contact" means these fluids need to get into your broken skin (such as a wound) or touch your mucous membranes (mouth, nose, eyes, vagina). The sick person also has to be far enough along in the illness — with enough virus in the bloodstream — to transmit the disease.



2) This means you can get Ebola by kissing or sharing food with someone who is infectious.



3) Mothers with Ebola can give the disease to their babies. Ebola spreads through breastfeeding — even after recovery from the disease. As one study put it, "It seems prudent to advise breastfeeding mothers who survive [Ebola] to avoid breastfeeding for at least some weeks after recovery and to provide them with alternative means of feeding their infants."



THE EBOLA VIRUS HAS BEEN ABLE TO LIVE IN SEMEN FOR UP TO 199 DAYS 4) You can get Ebola through sex with an Ebola victim. The virus has been able to live in semen up to 199 days after a patient started showing symptoms — well into recovery and long after the virus has disappeared from the blood.



5) You can get the virus by eating wild animals infected with Ebola or coming into contact with their bodily fluids. It's believed that the fruit bat is the animal reservoir for Ebola and that when it's prepared for a meal or eaten raw, people get sick. If that's the case, then you can get the virus through exposure to bat secretions. However, if you cook a bat infected with Ebola and then eat it, you won't get sick because the virus dies during cooking.



6) You can get Ebola through contact with a contaminated surface. Ebola is easily killed with disinfectants like bleach. But if it isn't caught, it can live outside the body on, say, a doorknob or countertop for several hours. In body fluids, like blood, the virus can survive for several days. So you'd need to touch an infected surface and then put your hands into your mouth or eyes to get Ebola.



This is why the funerals of Ebola victims are problematic. Someone who has died from the virus will have a very high viral load. Since the virus can live in bodily fluids on their body, if you participate in the ritual washing of an Ebola victim and then touch your hands to your face, you could get the virus.





7) You could also get the virus by working in a biosafety-level-four lab that studies Ebola, touching lab specimens, and then putting your contaminated hands to your mouth or eyes or on a cut.



8) You can get Ebola by being pricked with a needle or syringe that has been contaminated with the virus. This has been a source of transmission for health workers. But unless you're an Ebola health worker or sharing needles with Ebola victims, this isn't likely.

How you can't get Ebola

1) You can't get Ebola from someone who is not already sick. The virus only turns up in people's bodily fluids after a person starts to feel ill, and only then can they spread it to another person.



2) You can't get Ebola from just sitting next to an asymptomatic, or even mildly symptomatic person on, say, a plane or subway. As one of the Ebola discoverers, Peter Piot, said, "I wouldn't be worried to sit next to someone with Ebola virus on the Tube as long as they don't vomit on you or something. This is an infection that requires very close contact."



YOU CAN'T GET EBOLA FROM MOSQUITOES 3) You can't get Ebola from mosquitoes. The CDC says, "Only mammals (for example, humans, bats, monkeys and apes) have shown the ability to spread and become infected with Ebola virus."



4) It's pretty difficult to get Ebola through coughing or sneezing. The virus isn't airborne, thankfully, and experts do not expect it to become airborne. So, as the Centers for Disease Control and Prevention explained, "If a symptomatic patient with Ebola coughs or sneezes on someone, and saliva or mucus come into contact with that person's eyes, nose or mouth, these fluids may transmit the disease." This happens rarely and usually only affects health workers or those caring for the sick.

The bottom line: Ebola is very difficult to catch

The scenarios under which Ebola spreads are very specific. And Ebola doesn't spread quickly, either. A mathematical epidemiologist who studies Ebola wrote in the Washington Post, "The good news is that Ebola has a lower reproductive rate than measles in the pre-vaccination days or the Spanish flu." He found that each Ebola case produces between 1.3 and 1.8 secondary cases. That means an Ebola victim usually only infects about one other person. Compare that with measles, which creates 17 secondary cases. NPR has an excellent graphic to this effect:

If you do the math, a single case in the US could lead to one or two others. (That's what happened in Dallas in 2014: one patient infected two nurses when he was very sick and therefore very contagious.) Because we have robust public health measures here, the virus didn't spread farther than that. Compare this situation with West Africa, which had to deal with more than 25,000 cases in a completely broken and underfunded health system. That's where experts say the worry about Ebola should be placed.

We don't know where Ebola lives when it's not in humans — and other Ebola mysteries

Science is always evolving and never certain. And because Ebola is a rare disease, there are still many scientific avenues that need exploring.



One of the enduring questions is where Ebola lives when it's not in humans. Hunting for viruses is no easy task, and Richard Preston, author of the Ebola book The Hot Zone, summed up why this mystery has stumped virologists since Ebola was discovered:

It's just a weird conundrum. The scientists are all scratching their heads. It's an interesting problem. The guy who wrote the textbook on Ebola explained it to me: there is a gold standard proof that the Marburg virus (an Ebola cousin) lives in a particular species of bat. They've proved that. But that's Ebola, not Marburg. They are both members of the filovirus family. With Ebola, there's a lot of speculation that it could be living in fruit bats. The fruit bat carries Marburg. Could Ebola be in fruit bats? Living Ebola has never been found in a fruit bat. So maybe it could be in a tiny little tick or insect that lives on the body of a bat, and then it's infecting the bat and the bat infects a human. Those fruit bats are incredibly common in Africa. People eat them. They are supposed to be delicious. So there's all this contact between bats and humans. Shouldn't there be more Ebola? But there isn't. Ebola could easily live in an arthropod. But go into a rainforest environment — ecologists haven't even given names to a lot of the insects there, and when it comes to mites and ticks, forget it. Even experts have real trouble distinguishing one species of insect from another. All of a sudden, you have to test thousands of creatures for Ebola and you still might not have found Ebola because it might be in that insect you didn't test. There's something here we're not seeing.

Scientists also aren't sure why some people get Ebola and others don't. They don't know why some folks with Ebola never show symptoms and can't spread the disease to anyone, while others are "super-shedders" with very high viral loads — and are therefore very contagious. They are still learning about the long-term side effects of Ebola, and whether survivors have lifelong immunity to the virus (meaning they can't get it more than once).



Some researchers are looking into whether Ebola today has mutated to become more contagious than it was previously, and how that will impact the reproductive rate of the disease. (So far, it seems it evolved at a normal rate this time around.) Most scientists aren't concerned that the virus will mutate to become airborne, however, since a virus has never been known to change the way it's transmitted.



The unprecedented scale of the current outbreak is tragic, but it will hopefully help answer some of these questions. In fact, this epidemic has already served up new insights into the virus. First, the traditional approach to containing an Ebola outbreak — tracing the contacts of the infected person and isolating them — is extremely difficult to scale when thousands are involved.



The second lesson relates to how Ebola spread today versus how it spread when it was discovered in 1976. Because of the changing economic and social dynamics in Africa, people travel more than they did in the past, and many regions have urbanized. This means outbreaks are less likely to be relegated to rural and remote areas and can therefore get much larger. Which means, Michael Specter pointed out in the New Yorker, "in a world where almost any incubation period is longer than even the farthest plane ride, we are all only as safe as our most vulnerable nations."



A final insight: Ebola can be a survivable disease with the proper supportive care. When people get antibiotics quickly and have their fluids replaced, they tend to live. But, again, this is truer in strong health systems with good access to care than it is in impoverished countries like Guinea, Liberia and Sierra Leone.



To learn more about the latest science, the New England Journal's Ebola outbreak page and Science's special Ebola collection are great resources.

Ebola never spread to this many countries before

Before 2014, Ebola was a disease that was mostly confined to remote African villages. Health officials didn't worry about it reaching epidemic proportions.



And then Ebola went global.

THE CURRENT EBOLA EPIDEMIC IS OUTRUNNING OUR ABILITY TO STOP IT Ebola first appeared in 1976 during twin outbreaks in Zaire (now the Democratic Republic of the Congo) and South Sudan, likely spread by bats from nearby jungles. Since then, there have been 20 other outbreaks, but they have usually occurred in isolated rural areas and died out quickly. The countries involved — DRC, Gabon, Sudan — have experience in stamping out the virus before it spreads.

This year has, in many ways, changed people's notions of how Ebola can move through populations. In December, the virus is believed to have first turned up in the body of a 2-year-old boy in Guéckédou, a rainforest region in southeastern Guinea. (Specifically, researchers now contend that he might have played in a tree filled with fruit bats and contracted Ebola that way.)



The geography was unfortunate: Guéckédou happens to share a very porous border with Sierra Leone and Liberia, where people travel in and out every day to go to the market or conduct business.



By the time the Ebola outbreak was identified in March, it had already spread to all three countries along the border.



And it kept spreading: in July, a Liberian American got on a plane bound for Nigeria, bringing the virus with him and spurring 20 cases and eight deaths in Africa's most populous country. Soon, another case turned up in Senegal. The US faced its first-ever cases and transmissions of Ebola in Dallas and New York City. In Spain, a nurse who had been caring for a repatriated priest got the virus in Madrid.

Mali confirmed an Ebola case last October: a 2-year-old girl who had recently returned from neighboring Guinea who has since died, leading to the discovery of several other cases and deaths. In December 2014, a health worker returning from Sierra Leone to Glasgow, Scotland, was diagnosed with the virus.



That's nine countries hit with Ebola in one year. There's never been an Ebola outbreak like this before.

The usual methods for containing Ebola, like tracing patients' contacts, haven't scaled to outbreaks of this size

By October 2014, Senegal and Nigeria were declared virus-free, having stopped their small outbreaks. By November, so was the DRC. Mali also has zero suspected cases. In Scotland and the US, the virus did not travel very far.

The epidemic drags on in West Africa

On May 9, 2015, Liberia was finally declared virus-free, but there are still cases in Guinea and Sierra Leone, "creating a high risk that infected people may cross into Liberia over the region's exceptionally porous borders," the WHO warned.



The epidemic has dragged on in West Africa, in part because the usual methods for containing Ebola — like tracing patients' contacts — don't scaled to outbreaks of the size that Liberia, Guinea, and Sierra Leone had to battle.



In the past, public health officials had a playbook for stamping out Ebola. Because the disease isn't very contagious and spreads slowly, they just needed to find all those infected, quarantine them, and identify everyone they'd been in contact with. This could be done in sparsely populated rural areas or places with only a few cases.

But an epidemic is much harder to contain when suddenly many countries are dealing with hundreds or thousands of cases. Since West Africa had never seen Ebola, the virus had a three-month head start before health officials in the countries involved even realized they were harboring an outbreak. It didn't help that the international community was very slow to bring aid to the region, only declaring a public health emergency in August, five months after the first international spread.



For these and other reasons, the current Ebola epidemic in West Africa continues to burn. "It's like a forest fire," Ron Klain, the US's Ebola czar said recently. "A few embers burning, and the thing can reignite at any time."

All but two of the Ebola patients treated in American hospitals survived

On September 30, 2014, the Centers for Disease Control and Prevention announced that Thomas Eric Duncan, a patient in Dallas, had Ebola — the first time the disease was diagnosed in the US. He died nine days later.



After that, two health workers who cared for him got sick, spreading fear and panic among the health-care community and the general population. First, on October 12, Nina Pham — one of Duncan's nurses — tested positive for the disease. This was the first-ever transmission of the virus in the United States. On October 15, officials announced that a second nurse, Amber Vinson, had gotten the virus while caring for Duncan, too. Both were later discharged from the hospital, virus-free.



In addition to Pham and Vinson, several other Americans have been infected with Ebola. So far, almost all of them got the virus while working in Africa, received treatment in the United States, and survived.



In October 2014, a doctor in New York City tested positive for the virus. Dr. Craig Spencer had been working with Doctors Without Borders in Guinea. He was well when he departed West Africa and only fell ill days after arriving in the US. He recovered and was released from Bellevue Hospital in New York in November.



That month, Sierra Leonean surgeon and permanent resident of the US Dr. Martin Salia was flown to Nebraska Medical Center after catching Ebola while working in a Freetown hospital. He was already in critical condition when he arrived, and he died two days later.



Nebraska Medical Center also took in Ashoka Mukpo, a freelance cameraman who was infected with Ebola while working in Liberia with NBC News. He has since been released and declared Ebola-free.



Before him, an unnamed American who worked for the World Health Organization in Sierra Leone returned to Emory University Hospital in Atlanta for treatment and was discharged, also surviving the disease.



Three American medical missionaries — Kent Brantly, Nancy Writebol, and Richard Sacra — came down with the illness in Liberia. Brantly and Writebol were treated at Emory. Like Mukpo and Salia, Sacra was treated in Nebraska. All have survived.



Patrick Sawyer, a Liberian American, got Ebola in Liberia, where he worked at the Ministry of Finance. He died in Lagos, Nigeria, in July.



Another health worker was flown back from Sierra Leone for treatment at NIH in March 2015, and discharged, virus-free, a month later.

How Americans are beating a disease with a 70 percent fatality rate

This virus didn't change when it arrived in the US. But its medical setting did. It is true that the average West African has a lower life expectancy than the average American. And a much smaller number of Americans have so far contracted — and been treated for — Ebola. But as we have seen, those who have show remarkably good results.



"Yes, it’s a small sample size," says Dr. Ashish Jha, director of the Harvard Global Health Institute, adding that there are still "enough data points to say there's something meaningfully different."



The virus didn't change when it arrived in the US. But its medical setting did. Until this year, Ebola was treated in rural and remote areas of some of the poorest countries on Earth.



Through this epidemic, doctors are learning just how much quick diagnoses, ready access to life-sustaining tools and drugs, and good infection-control practices seem to matter when it comes to a disease that was once believed to be a death sentence.

For every four cases of Ebola we know of, there might be six that we don't

While official estimates suggest there are already more than 25,000 cases of Ebola during 2014 and 2015, the real number is likely much, much higher. The Centers for Disease Control and Prevention estimate the actual number of Ebola cases is roughly 2.5 times higher than the reported figures — so for every four Ebola cases we know of, there could be six that we don't.



The CDC isn't alone in this. "There is widespread underreporting of new cases," warns the World Health Organization. The WHO has continually said that even its current dire numbers don't reflect the full reality. The estimated Ebola cases in West Africa could just be the tip of the iceberg.

To understand how an Ebola case could be missed, you need to understand what it takes to actually find and count a case.



Oftentimes, potential cases are communicated through dedicated hotlines, which citizens can call to report themselves or their neighbors. Health workers or doctors can call in cases, too. These reports are forwarded to local surveillance-response teams.



All these cases need to be followed up on and verified to be counted. To do that, a team of two to four investigators is dispatched to hunt for the suspected Ebola victim.

Tracking down Ebola cases is difficult in places where the roads and communication infrastructure are poor

Actually tracking these people down isn't straightforward, especially in areas where the roads and communication infrastructure are poor. Investigators can spend days chasing a rumor.



These health teams also work under constant stress and uncertainty. During this outbreak, they've faced violence, angry crowds and blockaded roads. They can't wear protective gear because they'll scare off locals.

When they finally locate an Ebola victim, he or she may not always be lucid enough to talk or even still alive. So the investigators need to interview friends, family, or community members to determine whether it's Ebola that struck — always keeping a distance.



If this chase appears to have led to an Ebola patient, the health team notifies a dispatcher to have that person transported by ambulance to a nearby clinic or Ebola treatment center for testing and isolation.



If the person is already dead, they notify a burial team, which arrives in full personal-protective gear. The team puts the body in a body bag, decontaminates the house, swabs the corpse for Ebola testing, and transports the body to the morgue.



But confirming the cause of death doesn't always happen. There have been reports that mass graves hold uncounted Ebola cases. With limited resources, too, saving people who are alive tends to take precedent over managing and testing dead bodies.



Reported cases are then communicated to the ministry of health in the country. These reports are combined with counts from NGOs and other aid organizations working in the region.



The numbers come in three forms: lab-test confirmed cases, suspected cases, and probable cases. The WHO classifies a suspected case as any person, dead or alive, who had Ebola-like symptoms. A probable case is any person who had symptoms and contact with a confirmed or probable case.



The ministry of health compiles and crunches this information and sends it to the WHO country office. That office reports that to the WHO's regional Africa office in Brazzaville, Congo, and that message is passed along to Geneva, home to WHO's headquarters.

"At each step along the way, a case can fall out of the pool of 'counteds'"

To get to this point, Dr. David Fisman, an infectious-disease modeler working on Ebola, summed up: "A person needs to have recognized symptoms, seek care, be correctly diagnosed, get lab testing — if they're going to be a confirmed case — and have the clerical and bureaucratic apparatus actually transmit that information to the people doing surveillance. At each step along the way, the case can fall out of the pool of 'counteds.'"

The majority of Ebola deaths may not be from Ebola

Of this epidemic, the World Bank said Ebola may deal a "potentially catastrophic blow" to the West African countries reeling from the virus. Businesses shut down, people stopped working, kids stopped going to school. A report from the bank in December 2014 noted:

GDP growth estimates for 2014 have been revised sharply downward since pre-crisis estimates. Projected 2014 growth in Liberia is now 2.2 percent (versus 5.9 percent before the crisis and 2.5 percent in October). Projected 2014 growth in Sierra Leone is now 4.0 percent (versus 11.3 percent before the crisis and 8.0 percent in October). Projected 2014 growth in Guinea is now 0.5 percent (versus 4.5 percent before the crisis and 2.4 percent in October).

The epidemic has also led to 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 World Health Organization director warned. "In some areas, hunger has become an even greater concern than the virus."

People are going to suffer and die more from other diseases as the already scarce health resources in the region go to Ebola. Speaking at the United Nations, Dr. Joanne Liu, international president of Doctors Without Borders, said, "Mounting numbers are dying of other diseases, like malaria, because health systems have collapsed."



In a 2015 study in the journal Science, researchers focused on measles — the most contagious virus recorded — and applied statistical models to quantify the likelihood of an epidemic in the three countries worst hit by the virus. The researchers found that due to the health-system disruptions over 18 months, there could be up to 100,000 additional measles cases and between 2,000 and 16,000 additional deaths.



"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 an article in the New England Journal of Medicine.



So this virus has wreaked incalculable damage on not only the bodies of those infected, but also on others who are not getting health care they need, and on the health systems and economies of West Africa.



Dr. Ezie Patrick of the World Medical Association, who is based in Abuja, Nigeria, focused on the simple and disquieting fact that Ebola has also taken the lives of health workers in places where the number of doctors per population is abysmally low: "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."



The disaster could last longer than the epidemic itself. Before the Ebola outbreak, West African nations were seeing promising signs of economic growth. Sierra Leone, for example, had the second-highest real GDP growth rate in the world. Liberia was 11th in 2013.



Now there's worry that Ebola will slam the brakes on that development. "A prolonged outbreak could undercut the growth 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."

More than 500 health-care workers have died from Ebola

One disturbing feature of the current epidemic is that so many health workers have lost their lives while caring for the sick or trying to spread public health messages about Ebola.



This is partly because Ebola is transmitted through bodily fluids, and no one has more contact with the bodily fluids of an Ebola patient than his or her doctor and nurse.



In the US, the only two people who contracted Ebola were health workers. In Africa, the situation is much more dire. As of May 2015, 507 health-care workers have died from Ebola. More than 800 contracted the disease.



To put that into context, in the second biggest outbreak in history — in Zaire in 1976 — 11 medical personnel died. And that was the first recorded outbreak, when measures to prevent transmission of the virus weren't well-established.



There are several causes for the current death toll.



The first is that health workers haven't had access to the supplies they need. Since the disease is transmitted through direct exposure to bodily fluids, they are advised to wear face masks, goggles, gowns, and gloves while caring for patients. But doctors and nurses in developing countries don't always have that protective gear.

Even if they have protective gear, doctors and nurses may want to use their scarce supplies only when absolutely necessary, which brings us to another reason for the alarming loss of health workers: many doctors caring for Ebola patients in West Africa, particularly in the early days of the outbreak, had no idea they were seeing Ebola patients. The disease had never appeared in that part of Africa, and it can be difficult to diagnose, sometimes masquerading as malaria or the flu until symptoms worsen. So doctors and nurses weren't always protecting themselves as they would from a deadly virus.



A third reason for the outsize health-worker death toll is that the total number of people infected with the virus this year is so much greater. In 1976, the death toll was 280, and there were 318 reported cases. In this 2014-2015 outbreak, that second number is much, much larger.

Finally, the scale of this outbreak requires medical personnel that just weren't at the ready in West Africa. Sierra Leone has 2.2 doctors for every 100,000 people. The OECD average is 320 per 100,000 people.

Poverty is one big reason why Ebola spread so quickly

Ebola can be stopped. But it takes resources and a functioning health-care system.



The three countries hardest hit by this Ebola epidemic — Guinea, Sierra Leone, and Liberia — have very weak health systems and little money to spend on health care. That constrained their ability to stop the spread of the virus.



In most of West Africa, health spending amounts to less than $100 per person per year (in the United States, it's about $8,000). Guinea, Sierra Leone, and Liberia have some of the worst maternal and child mortality rates on the planet — an indicator of a failing health system.



Experts point out that scarce resources make it extremely difficult to contain Ebola: "If you're in a hospital in Sierra Leone or Guinea, it might not be unusual to say, 'I need gloves to examine this patient' and have someone tell you, 'We don't have gloves in the hospital today,' or 'We're out of clean needles' — all the sorts of things you need to protect against Ebola," says Daniel Bausch, associate professor at the Tulane University School of Public Health and Tropical Medicine, who worked with the WHO on the outbreak.



Along with poverty and a health system too weak to combat the virus, illiteracy contributed to the problem. As you can see in the map below, Guinea, Liberia, and Sierra Leone (circled in green) have some of the lowest literacy rates in the world.

Poor literacy made it much harder for aid workers to mount a public health information campaign and explain to people how they can stop the spread of Ebola. It also helped fuel a rumor mill about supposed cures. For example, one persistent myth suggested that hot water and salt could stop Ebola. Others suggest that faith healing, hot chocolate, coffee, and raw onions might stamp out the virus. This misinformation, in turn, fueled Ebola's spread in the region.

Global health agencies were too slow in responding to the Ebola crisis

"Ebola is a very preventable disease," said Lawrence Gostin, a health law professor at Georgetown University. "We've had over 20 previous outbreaks, and we managed to contain all of them."



It could take months for a full response to get off the ground But this time, the international response just wasn't there. "There was no mobilization," Gostin said. "The World Health Organization didn't call a public health emergency until August — five months after the first international spread [in March]."



It took three months for health officials to identify Ebola as the cause of the epidemic (in March), another five months to declare a public health emergency (in August), and two more months to mount a humanitarian response. Consider that in June, Doctors Without Borders — which had been on the ground since the beginning — had already declared the epidemic "out of control."



Part of the reason for the slow response can be attributed to budget cuts and managerial confusion at the WHO that have left the agency understaffed and short on resources. According to a New York Times investigation, the WHO and the Guinean health ministry had "documented in March [2014] that a handful of people had recently died or been sick with Ebola-like symptoms across the border in Sierra Leone." But information about the potential cases never made it to senior health authorities in Sierra Leone.



Another investigation by the Associated Press found that much of the delay was due to political maneuvering within the United Nations.



The result was that it wasn't until May that Sierra Leone confirmed its first cases, leading to a cascade of contagion that spurred the record number of cases in West Africa.



The painfully slow response can also be attributed to the fact that the WHO now sees itself as a "technical agency," providing analysis and data, and not as a first responder. (But as an editorial in the journal Nature pointed out, "If the WHO is not the first responder to an emergency such as this, then who is?")

At the regulatory level, the International Health Regulations — an international law guided by the United Nations to govern disease responses — are also flawed and broken, leaving us unprepared for outbreaks. So this Ebola epidemic has served as a reminder of just how slow and poorly coordinated our global responses to outbreaks are, and this is a problem because any infectious diseases expert will tell you that the best way to stop an outbreak is to contain it early.





Sadly, the world only seemed to wake up to Ebola after two American missionaries got infected.



One of them, Dr. Kent Brantly, testified before the US Senate to make that point: "This unprecedented outbreak began nine months ago but received very little attention from the international community until the events of mid-July when my friend and colleague, Nancy Writebol, and I became infected." He added: "The response, however, is still unacceptably out of step with the size and scope of the problem now before us."

"[Ebola] could establish itself as an endemic infection because of a highly inadequate and late global response"

Still, by the fall of 2014, the global health community began moving aggressively to respond to Ebola. The director of the WHO called this Ebola epidemic the "greatest peacetime challenge" the world has ever faced. President Barack Obama said Ebola is "not just a threat to regional security … [but] a potential threat to global security." For this reason, the US sent thousands of troops to fight Ebola, funding the largest international response in the history of the CDC. In October 2014, the Obama administration appointed Ron Klain its first "Ebola czar" to coordinate the response.

In other desperate and unprecedented measures, the UN Security Council characterized the virus as a threat to international peace and security, holding its second disease-focused meeting ever and setting up a special UN mission to deal with the epidemic. It also unanimously passed a resolution asking countries around the world to urgently send medical workers and supplies to stop the epidemic.



There is one upside to the painfully slow Ebola response: it got the global health community talking about the changes that need to be made to the current order — including assembling armies of health workers that could be quickly dispatched, and setting out guidelines for rapidly testing drugs and vaccines in an outbreak — to prevent future outbreaks from growing similarly out of control.



Hopefully, the reforms come fast. As Gostin told Nature, "I want to emphasize the importance of making these changes now, while the epidemic is fresh in our mind, and not wait, because the political momentum is with us now, and it will fade the same way it did with SARS and H1N1."

There's no cure for Ebola — but a number of candidates are being studied

Even though people have known about Ebola for almost 40 years, vaccine and drug development for the disease has been slow at best. Notably, most of the investment in Ebola cures has come from government agencies (such as the US Department of Defense) interested in researching potential biological terrorism weapons — not in helping patients.



But the Ebola epidemic burning in West Africa has sparked unprecedented focus on finding an Ebola cure and speeding up the drug testing and approval process for current therapies being developed.



In September 2014, the drug company GlaxoSmithKline announced it took the extraordinary step of starting mass production on an Ebola vaccine that had just begun being tested in humans. (Companies typically wait for the clinical trials data to show their vaccines are safe and effective before manufacturing.) Merck also has testing for an Ebola vaccine candidate underway, and Johnson & Johnson will bring its vaccine to safety testing in 2015.



So far, the GSK and Merck vaccines have proven safe, and their efficacy trials began in early 2015. "If one or more of the drugs proves effective and safe, an Ebola vaccine could be ready by as early as next year," according to the New Yorker.

THE USUAL DRUG APPROVAL PROCESSES ARE BEING CONDENSED OR SKIPPED The news of vaccine development followed a decision by the World Health Organization to allow unproven and experimental treatments on people in this public health emergency — which means the usual drug approvals process will be condensed or phases of clinical testing potentially skipped, and that trials could be done amid the outbreak in Africa.



One promising experimental Ebola drug is ZMapp, an antibody therapy that was used for the two American medical missionaries infected in Liberia. The Ebola drug was developed by several stakeholders — Mapp Biopharmaceutical and LeafBio in San Diego, Defyrus from Toronto, the US government, and the Public Health Agency of Canada. It's made up of a cocktail of monoclonal antibodies, which are essentially lab-produced molecules manufactured in plants that mimic the body's immune response to theoretically help it attack the Ebola virus.

Another experimental therapy now being tried in humans is TKM-Ebola, developed by the Canadian pharmaceutical company Tekmira with the help of funding from the US Department of Defense. And another that has been tested in this crisis is brincidofovir, from Chimerix.



So why all the Big Pharma involvement in what has essentially been a neglected disease until this year? Perhaps there are altruistic motives and the desire for companies to help in this worst-ever outbreak. The public attention, and potential that governments will stockpile whatever medicine is eventually brought to market, may have also attracted Big Pharma to Ebola this year.



Some of the trials have hit roadblocks, since they only got started when the outbreak was already waning in West Africa — meaning there are few patients to test on. So this Ebola epidemic demonstrated we still don't have a framework in place for how to run drug trials in the middle of a pandemic or epidemic — a challenge that will surface with every outbreak.



Whether the development of such a framework — or a proven Ebola drug — actually turns out to be the silver lining of the worst Ebola epidemic in history remains to be seen. For every 5,000 compounds discovered at this stage, only about five are allowed to be tried in humans. These Ebola therapies are at only very early stages of drug testing, and they have a long way to go before proving useful.



What's more, an Ebola drug won't fix all the health-system issues that allowed the disease to spread in Africa. As Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, wrote in the New England Journal of Medicine: "While these interventions remain on accelerated development paths, public health measures are available today that have a proven record of controlling (Ebola) outbreaks. Premature deployment of unproven interventions could cause inadvertent harm, compromising an already strained relationship between health care professionals and patients in West Africa."