What it says on the tin. Having a character get a fungal infection that itself releases spores basically means that, without the ability to make them wait, there's nothing to stop them infecting your own character and the rest of your followers. That basically means you have to ditch them as they also then piss of NPCs.

I'd like to being to tell them to wait so you can park them out of range of NPCs, and I'd like to be able to spray them with the fungal cure (and please just forgo the corpse requirement, at least until you fix the AI so they are as assiduous in avoiding spores as the player is).