Yudishtira
Spiritual/Creative
More generally, would it be possible to make Disease work more like Flammability - i.e. the amount of Disease (as well as a random variable) is a trigger for events that cause disease outbreaks to occur for set amounts of time in cities. As it is presently, diseases are a constant presence as long as your Disease level is above the required threshold - indeed, your city is likely to have the Common Cold (only requires 1 Disease) for the entire game. By having disease outbreaks be tied to events that have a random element instead, it adds a degree of variability and unpredictability, plus it can better reflect how disease actually operates - i.e. periodic outbreaks instead of a constant presence, plus perhaps the events could include variables that allows disease to 'spread' from one city to another.
Firstly disease can very easily go negative, because Graveyard, Mausoleum (buildings), and Healer (early unit) and later Apothecary give decent negatives per turn to it.
That said, I prefer your idea to have random disease events triggered by disease property levels. They would have to happen much more frequently than flammability events do currently, because I pretty much ignore flammability, whereas I check the disease increase rate every turn, everywhere!
But you shouldn't all suddenly get 'the trots' at 50 disease - it's just doesn't make sense. If it's not going to be event-based, then it needs to scale up at 1 per 15 disease or whatever, and I'd still like a bit more randomness about it. I don't want more or less disease - I just think it ought to work differently.
I would also like crime to work the way you suggest. It seems to me even more appropriate, rather than forgers magically appearing and disappearing as you transgress or retreat from a property level.