[~Fierce~]

I wanted to contribute to this and I came up with two ideas, but it seemed likely that the second one wouldn't be considered so I decided to scrap it. @Moonraven

 

So, I have some doubts about this one but I think it could work. Perhaps, a patrol is out hunting when they catch an unfamiliar smell in the territory. They decide to follow it and it leads to where Windclan territory ends and the outskirts start. One or two cats decide to investigate and when they come back fairly quickly, they say they found the cat who the scent belonged to but they say that the cat didn't seem dangerous, just really sick and fragile, probably on the brink of death. They head back to camp to report to Twilightstar, but they don't notice that they're bringing a sickness back to camp.

What the patrol didn't know was that the cat had a disease and it was spread by fleas. The fleas spread the disease by biting the cat and then going on to infect others. The fleas spread by close contact and only cats who are very clean and healthy seem to not show symptoms to the disease. The disease takes a few days to show symptoms but as soon as it does, it leaves a cat very sick to the point where they can barely walk. If they survive, they are left in pain for many days, up to a moon sometimes. Those infected have to keep away from the other cats. The only other way that cats can be immune to the disease is to be covered in (insert strong smelling substance), as it seems that the fleas don't like the smell. These are only used for those who are brave enough to take care of the cats, like bringing them water and prey.

It takes a while but soon, a cure is found. If you eat mint leaves and then go submerge yourself in water, then the fleas will die cause of the water.

The cure doesn't make sense, I know, so you can edit it to make it more realistic.