Once the infected person begins to show symptoms—flu-like aches, nausea, and vomiting—local customs continue to play a big role. There aren't enough doctors or supplies available to treat all the Ebola patients in the area, but even if there were, many locals are suspicious of Western medicine.

“In this outbreak, there's been intense mistrust of Western health care workers,” Epstein said. “You're battling a lot of perceptions and convictions. There are local remedies that people have trusted. They will turn to a local witch doctor in the village.”

If the person dies, tradition holds that the body should be washed by the family, which inadvertently creates new opportunities for exposure. The family member might then prepare a meal for the rest of the funeral party, further increasing the odds that infection will spread.

When the infected person dies in a medical tent, meanwhile, the body is usually disinfected and buried or burned, not returned to the family. This causes enormous agony for the families—“it enhances grief if people aren't allowed to perform the rituals that are important to them,” Epstein said. “So if someone dies, they'll secret the body away.”

Then there’s the fact that because Ebola is so deadly, those who enter a Western-established medical tent might never come back. That heightens fears among locals that Western doctors might be worsening the outbreak. People start to hide their sick relatives, who bleed out at home and infect others. One Sierra Leone woman fled a hospital after testing positive for the Ebola virus. Other communities are preventing doctors from entering entirely.

“So why don’t people avoid the bats in general?” I asked.

“Eating wildlife is a generational practice,” Epstein said. “It's something people have done forever. There isn't necessarily an association with the animals they're hunting or killing and getting sick. Even if they're told by local doctors that bushmeat is making them sick, there's a strong belief that the illness is due to black magic or spiritual power.”

It’s tempting to blame local customs, but less so when you realize that Ebola is an extremely rare virus, and food options in the bush can be extremely scarce. One might eat five or 10 or 100 bats and be fine, but the 101st might be lethal.

Think of it this way: “We know there's mad cow disease, but does that stop you from eating hamburger?” said Sarah Olson, a wildlife epidemiologist at the Wildlife Conservation Society.

“They've probably never seen Ebola, and they’re balancing that against a need to feed their family," she added. "The risk of contracting it is very low, but when you multiply that across many interactions, occasionally it's going to happen.”