There should be some rule for contagion, but it can cover a large variety of conditions, not all of which are contagious (cancer, Lupus etc.) or are not contagious to the other PCs - Elfasclerosis might not affect non-elves, and Filth Fever won't affect party members who remain clean). But some things will spread like the plague. An example is the plague.MartinHarper wrote: I agree that 4e poison sucks. The disease mechanics work better for poison, I reckon, with a final state of "dead". Meanwhile, the disease mechanics suck for diseases, because they're not contagious, which is surely the whole point of a disease.
I think you could have more fun playing 4E as a game of House (trying to identify someone's condition and find the right way to cure them, possibly including breaking into their house and stabbing the guards in the face, all before they succumb to the illness and die) than as regular 4E.
"We've tried everything for Cackle Fever and he's just getting worse. The laughing is terrible, and he's sweating so much that his skin is going rubbery."
"Gregorius, stop stealing my food, I'm not exactly tickled at having to buy my lunch twice every day."
"...tickled."
---
"You, why are you laughing?"
"I can't help it, my insides tickle."
"I thought so! You have Slimy Doom. All we need is a paralytic poison and an Ooze Puppet spell, then we can cure you!"