The largest outbreak of ebola ever recorded is spreading in West Africa, and it’s unlikely to end soon. According to the latest figures from the World Health Organization — which are constantly ticking up as new cases are detected — 528 people have been infected with the virus and 337 have died. That’s already much worse than the previous largest outbreak, when 426 people were infected and 172 died in Uganda in 2000.

But this latest outbreak isn’t just infecting and killing more people — it’s also much more geographically spread out. Cases have been recorded in Guinea, Sierra Leone, and Liberia. Some victims turned up in Conakry, the capital of Guinea, and in a town 40 miles from Monrovia, the capital of Liberia, which is worrisome because diseases spread more quickly in densely-populated areas.

Aid organizations are setting up emergency clinics and employing hundreds of international and local health workers. "The epidemic is out of control," Dr. Bart Janssens, director of operations at Doctors Without Borders, said in a statement yesterday.

Ebola is an all-around horror show; it’s fast-spreading, deadly, and brutal, one of a class of highly contagious hemorrhagic fevers that cause the blood to attempt to escape the body through any means possible. Late symptoms can include genital swelling, bleeding from the ear, nose, eyes, mouth, and anus, and a skin rash that contains blood. Transmission occurs through sweat, blood, saliva, or sexual fluids.

So how scared should we be?

Those most at risk by far are the family, friends, and neighbors of those infected. No travel advisory has been issued, and while the international airport in Conakry has started checking temperatures before allowing people to fly, medical authorities don’t think it’s very likely that the epidemic will spread globally. Furthermore, while there is no vaccine or cure for ebola, a patient in a modern hospital given an IV and blood transfusions has a good chance of fighting it off.

"Close contact with an infected person’s bodily fluids is required for human-to-human transmission," says Donda Hansen, a health communications specialist at the Centers for Disease Control who is working for World Health Organization (WHO) on the outbreak. "The virus is spreading because people ill with Ebola are crossing borders to access medical care they perceive as better, families are transporting family members who have died from Ebola to other locations for burial, others refuse medical care out of fear." In addition, some local communities have burial rites that involve washing the corpse and eating in the same room with it — a good way to catch the disease.

Dr. William Fischer, a critical-care doctor and professor at the University of North Carolina (UNC), was pretty scared when the WHO told him to leave his desk job in Geneva and head to Guéckédou, a large town in Guinea, to treat ebola victims.

"The fear was really tough," Dr. Fischer, who returned to his wife and two children in North Carolina last week, tells The Verge. "It was not just about dying or getting infected. I was really worried that I was going to be ineffective. Those concerns were equal."

Dr. Fischer’s time in Guinea was chronicled in his emails to family and friends, which UNC republished with permission. He describes the bulky full-body protective suits that got to be 115 degrees Fahrenheit inside on a not-that-hot day, the chickens that would wander into the isolation ward, and the one patient who would dance around pretending to do calisthenics in order to cheer him up.

He also describes the heart-wrenching stories of a 27-year-old man who lost all his strength while his sick sister was in the next room, and the pregnant woman who had both ebola and malaria and delivered a stillborn fetus. "Miserable," he wrote.

One day Dr. Fischer’s clinic received a young boy who had been locked in a house with his mother for four days until she died. The boy died overnight.

I can’t help but think about what his last days were like – being locked in a house with his mother by his family and his community out of fear; then watching his mother die in the back of a pick up truck, being placed in an isolation zone staffed by foreigners in space suits, and finally vomiting blood alone.Despite the wretchedness of the disease, Dr. Fischer says it looks much less dramatic than it does on television. "It’s not like the movies," he says. "The symptoms are nausea, vomiting, fever, and malaise — meaning weakness or fatigue — and diarrhea. Patients look just like the patients you take care of normally."

The quiet onset is another reason why ebola is so scary. The incubation period is about 21 days, meaning an infected person can travel far and have contact with a lot of people before realizing he or she is sick.

The first cases in the current outbreak were reported to the WHO in March, which means the epidemic would have started earlier.

Ebola may be spreading to humans through the saliva of fruit bats, which nibble on mangoes that later get eaten by humans, says Dr. Hilde de Clerck, a hemorrhagic fever specialist with Doctors Without Borders who spent two months treating patients and setting up clinics in the region.

"Most ebola outbreaks start when a single human being gets infected by the animal," she says, but the question of how the outbreak started is "more of scientific interest." "For now, it’s not the most important question. The most important is how we could manage to block the epidemic."

Right now the only way to stop the spread of the virus is to keep the victims from spreading it themselves. Neighboring countries have instituted road stops and border checks to stop the sick from crossing the border, although a quarantine is not advised because it would cause panic and be impossible to enforce. "You try to quarantine people in one place, they slip out the back or find a way out," says Dan Epstein, a communications officer for the WHO. "The only way really we can stop the spread is education."

Doctors Without Borders, WHO, the Red Cross, and other organizations are working together to combat the epidemic (and all three take donations on their websites). The trajectory of the epidemic is difficult to predict, de Clerck says, but it looks like it will last at least six months — although for the doctors and patients dealing with the devastating disease, that must seem like an eternity.