See, we know how to prevent rabies, but we have absolutely no idea how to cure it. In fact, we don't even really know how it kills people. Despite (and, perhaps, because of) its status as one of the first viruses to be tamed by a vaccine, rabies remains a little-understood disease.
What about all those stories you hear of someone being bitten by a rabid animal and having to get painful shots? I thought that was the cure, but it turns out those shots are actually a vaccine after the fact.
"You think about flu, that's a very quick virus. You develop symptoms in a couple of days. In a week, it's passed. But rabies incubation is very long," said Zhen Fu, DVM Ph.D., professor of pathology in the College of Veterinary Medicine at the University of Georgia. "It may be weeks or even months before you develop an active infection. So we have enough time after a bite to immunize with normal vaccine and bring up the immune system."
New treatments for vaccine show promise, but with few cases to study, the results are not conclusive. Maggie Koerth-Baker researched the disease after she found a bat in her living room. Link
(Or, if you live with ^monia^!)
Incidentally, don't get exposed to rabies if you don't have insurance. without it, this would have cost me around $6,000.