I've not dealt with ringworm myself, but I've heard tales from people who, much like you, adopted a cat that turned out to have it. None of them had experiences differing much from what you've already related - it's a pain in the butt and it takes a minimum of weeks to go through the quarantine and treatment. Main thing I can relate is that they all got through it okay, and probably with less effort put into sanitizing than it sounds like you are doing. (Not to discourage you from doing it, especially if the cat had the run of the house for some time before diagnosis.)
BTW, for anyone picturing actual creepy crawly worms, that's another annoying thing about ringworm - its name is very misleading. No worms involved, it's a fungal skin infection.
Thanks so much for your reply.
Yes, ringworm is a misnomer of sorts, since it's caused by multiple species of fungi. The most common one in cats is
Microsporum canis. Of the many other fungi that cause ringworm infection, there are even some that are emerging as resistant to standard treatment, just like other pathogens.
We're going into our cat's room a few times a day to clean his litter box, change his food and water, and give him some attention. But it's not the same as when he was happily running around the house. He's fearful, hiding under the bed, and meowing loudly when he's alone in the room.
The guidance on cleaning up the environment is variable. We've been leaning toward doing more rather than less, even wearing gloves and gowns when entering his room. I'm still unclear on what it will take to fully decontaminate the house, though. Fur, which is where the fungus attaches, is impossible to completely eliminate. I don't know how much everything will have cost when it's all over, but I suspect it'll be in the thousands, much of it for treatment and testing. The medications often used for feline ringworm can be hepatotoxic, so periodic assessment of liver function is often recommended. Of course, that will require putting the cat in a carrier and transporting him, with its own risks.
One piece of advice for anyone adopting or otherwise acquiring a cat: have it thoroughly checked for ringworm by a vet before you take it home. We brought our cat to the vet the day after we got him to ask about feeding and a few other things. I can't say for sure if the spot on his ear was there at the time, but I suspect it was. However, the initial exam wasn't specifically tailored to looking for ringworm, which requires a Wood's lamp exam that causes the fungus to fluoresce bright green under UV light.