Ebola is one of the deadliest diseases on Earth. Here's the fundamentals of where it comes from, how it spreads, and how it can be stopped.
Why was Ebola big news in 2014?
The deadliest Ebola outbreak in recorded history started in Guinea in early 2014 and soon became unprecedented in the number of cases, number of deaths, and in geographic scope.
Although Ebola is technically not the easiest to catch, it can be very deadly. Since the first outbreak in 1976 through the end of 2013, Ebola viruses have killed roughly 60 percent of those they has infected. Symptoms — including flu-like fever and vomiting, and sometimes bleeding — can come on quickly and kill fast.
Journalist David Quammen put it well in a New York Times op-ed: "Ebola is more inimical to humans than perhaps any known virus on Earth, except rabies and HIV-1. And it does its damage much faster than either."
In many ways, how well a country can deal with an Ebola outbreak comes down to basic health-care practices. And this outbreak started and grew in Guinea, Liberia, and Sierra Leone — some of the poorest countries in the world.
In addition, this was the first major Ebola outbreak in West Africa, where many of the region's health workers didn't have experience or training for the disease. And the outbreak started in an area with a lot of cross-border travel, which may have helped the virus disperse geographically and made it difficult to track down people who might be infected.
And on top of all of that, the global health response was both late and weak — and allowed the epidemic to spin out of control.
As the epidemic grew and grew, it seemed like it was only a matter of time before Ebola patients came to the United States. And when they did, the media — and the public — finally seemed to take notice.
All told, by the end of 2014 the virus had infected thousands. And it still wasn't finished.
Where does Ebola come from?
Ebola tends to come and go over time. The viruses are constantly circulating in animals, most likely bats. Because Ebola can infect animals, it can completely disappear from humans for years at a time while hiding away from our view. For example, there were zero recorded cases of people with Ebola in 2005 or 2006.
Every once in a while, though, the disease spills over into humans, likely when someone handles or eats undercooked or raw meat from a diseased ape, monkey, or bat. From there, it can pass from person to person, causing an outbreak that spans several months to years. And then, after the outbreak stops, it becomes quiet again.
Does Ebola really make people bleed from their eyes?
Yes. Some, but not all, patients may experience bleeding from orifices — one of the more unusual and memorable symptoms of viral hemorrhagic fevers like Ebola. In later stages of the disease, some people bleed from the eyes, nose, ears, mouth, and rectum. They may bleed from puncture sites if they've had an IV. And internal bleeding can happen, as well.
External bleeding can be one of the main symptoms that can help people realize they're dealing with a case of Ebola. That's because the first symptoms, which come on abruptly after an incubation period of 2 to 21 days, are things like fevers, headache, vomiting, and diarrhea — which are fairly nonspecific and can be caused by any number of illnesses.
But bleeding doesn't always happen. Not by far. For example, this study of a 1995 outbreak found external bleeding in 41 percent of cases. And bleeding also didn't correlate with who survived and who didn't.
If a patient dies from Ebola — usually between day 6 and 16 of the illness — it is from shock from multiple organ failure, including problems with the liver, kidneys, and central nervous system.
Why is Ebola so deadly?
One of the main things that seems to make Ebola viruses especially deadly is that they appear to be able to evade much of the human immune system. Among other problems, white blood cells from the immune system are often seen to die off in patients. And if the body can't fight fully back, the virus can just keep taking over.
Scientists are still figuring out exactly how this happens, and they have several promising leads. One is that the virus is making proteins that act as decoys, interfering with the body's ability to fight back.
The deadliness of Ebola can also depend on the level of care a patient receives — especially whether doctors have the ability to replace the fluids patients lose while they are ill. During the West African Ebola outbreak, only about half of the people who got the disease survived. Meanwhile, those who were treated in the US almost uniformly lived through the disease.
How hard is it to catch Ebola?
Ebola doesn't tend to hang out in the air like some other viruses, such as measles, SARS, or some kinds of the flu.
People contract Ebola by touching the blood or bodily fluids (including vomit, diarrhea, semen, and possibly sweat) of a person or animal who's infected (alive or dead). But you need to have "direct contact"with these fluids, meaning they need to get into your broken skin (such as a wound) or touch your mucous membranes (mouth, nose, eyes, vagina, etc).
People generally aren't infectious until they get sick, and as the virus takes over their bodies, they become even more infectious.
Still, the fact that people need direct contact with the virus means it's actually quite difficult to catch. Ebola's limited transmission ability is one of the main reasons why outbreaks can often be stopped within weeks or months. What it takes is public education and good health-care hygiene like isolating patients, sterilization procedures, and the use of gloves, masks, and other protective gear.
Many health care workers died in the most recent outbreak, likely because they hadn't been fully following strict protection procedures. "There have obviously been lapses somewhere in how the doctors and nurses have protected themselves," a World Health Organization spokesperson told Vox.
How do you treat Ebola?
Patients are treated for symptoms, including with IV fluids for dehydration. It's important to remember that people can survive an Ebola infection. In the West Africa outbreak, more than half of Ebola victims survived.
As researchers search for a vaccine or cure, the most recent outbreak taught doctors that the current best methods for treating Ebola patients are rather basic: keeping patients hydrated to replace lost fluids, giving them antibiotics to help their bodies fight other infections, and in more modern health systems, using technology to support organs that might be failing.