If you were to guess the deadliest virus on earth, the odds are good that you'd guess rabies. The only reason you wouldn't is because you don't think of rabies as something that would affect you or someone you love. We've done a pretty good job in isolating people from the Rabies lyssa virus, by living indoors, having our animals vaccinated, and using vaccine treatment in the case of an animal bite. People who work with animals get rabies vaccines ahead of time. But lyssa is still a deadly virus because it works its way around your immune system. If it gets to the brain without treatment, you're a goner. And it's a horrible way to die. Kurzgesagt explains how the lyssa virus works inside one's body, whether that body belongs to a wild animal or a person. Despite the displayed length, this video is only nine minutes long.