Cookies Run Kingdom?

A long time ago, a disease spread rapidly through the kingdoms

It started with a mild cough, a mild fever, and a lack of appetite until months later everything worsened.

Moo began to grow on the Cookies' bodies; little by little they lost consciousness until they simply died silently, their bodies like empty shells that moved. They became infected through gentle bites and scratches.

now:

Everyone took refuge in the Vanilla Kingdom; defenses had been raised to the maximum, and everyone was afraid. Soon, a cure was designed, but the problem was that it could only be used for stages one and two.