Pandemic/Epidemic

Perhaps if a city stays unhealthy too long, there's a random chance of the "sick" spreading to other cities in the general area. If the pandemic isn't checked, it can spread as an epidemic.

Lots of people would die in the cities of course.

I'm not sure how it can be fixed, though. Using cities to build "medicines"?

In some "space-empire" games this was a very good point. Some isolated world spreads a plague, and you need to create a vaccune-special-type vessel and send it to the worlds before is too late.

One way to implement this is if you have hospital, you can make a medical battalion to plague emergences in the citys with hospitals (only if there one plague active). When the plague disspaears, the non used medic battalions dissapears too (they're vaccune is not effective for further plagues). Before hospitals, maybe the medic battalion can only be made in capital, or a city with special wonder (medical type). Maybe only one civ can cure the plagues and the others has to negotiate the cure.

Too much complicated for the "general strategic" civ we have actually, but nobody knows if civ 5 will be more specific and deep...

Some ideas to add off the top of my head, having to do with disease.

Maybe have the option for a seiging army to throw disease ridden carcasses over a city wall, inducing a pandemic (catapult promotion/special ability?)

If a disease becomes to out of control in a city, you could have the option to quarantine the city. This would stop the plague from spreading, but also cut off trade routes to the city, or the city suffers a financial loss.

Quarantine -- good idea.

Perhaps epidemic would be a good idea, but I don't really think they should be directly related to the health that is currently in the game. I don't know how they would be represented, but what is currently in the game already has penalties that limit population, and cause population loss (albeit represented through starvation). Perhaps epidemics could be a random event? Although you would want some more control over them, I guess.

Well, if a city is unhealthy, there's probably rats or insects or whatever. And they get onto the ships or wagons and spread to other cities.

Well, I guess hospitals can't hold epidemics, not even now. Example: A flu.

The problem is that unhealthy, in ancient games, doesn't represent just diseases, but the general unhealthy living conditions caused by drinking out of the same drainage systems you empty your garbage into. All cities in the ancient and medival era should be unhealthy if we were to be realistic. But there's an unhealthiness from having a smallpox epidemic and an unhealthiness from drinking crap-water, and these are not exactly the same thing - just like there's a difference between being unhealthy from getting swine flu and being unhealthy because you eat McDonalds every day.

To implement a disease system, it would have to be influenced by many factors, not just unsanitary conditions. While lack of sanitation certainly exacerbates a plague, it can't be the instigating factor.

Two ideas for "curing" sick:

1) Sacrificing the sick population: Angry faces
2) Quarantining: No access to resources and no trade until it's gone.

Have you seen RFC's plague? Everyone hates that.

This idea sounds perhaps like it would be better just as a random event. Unhealthiness is already represented in the game, and the creation of a pandemic at a particular level would invariably be arbitrary, which is a bit of a bad measure to build an aspect on. A random event occurring more frequently with growing levels of unhealthiness would be the best solution.