Fractal degeneration

Fractal degeneration was a debilitating disease that struck only Valuerta, caused by a lack of radiant pink sunlight from their star.

It occured in a series of steps. First, after their skin had turned from pink to gray, paralysis to their limbs would occur. Various parts of their bodies would then peel and begin to fall off. Eventually, larger and larger pieces would decompose before the rest of the body fell apart and shattered as it hit the ground. This process sped up as more and more was lost, resulting in a prolonged torture before a quick death.

Basically what occured was a complete deatomization of the Valuerta.

Scientists studying this peculiar phenomenon noted that the radiation from Vleek must have had a heavy particle or series of heavy particles that when scattered through the atmosphere of Vleekstral became absorbed through their skin, and kept their systems in check.

Behind the scenes
This is loosely based on diseases such as leprosy.