Rabies is actually a great comparison. It has similar magical/horrifying feel to it. Like with the screwdriver slip-up, catching rabies can look like a total non-event; here, it doesn't kill you yet, merely starts the timer on a bomb. The countdown can be anything between days and years, and when it runs out - when the first symptoms start showing - you're already dead. Then the dying happens, which... relative to radiation sickness, I'm really not sure which is better.

To add an insult to injury, rabies is very much curable before the symptoms show - but you have to realize you may have been exposed in the first place.