I dunno why.
Garish Tattoo [0]
This particular disease crops up on a number of timelines; it’s pretty obviously a bioengineered one, but nobody’s sure who is creating it, and how they’re spreading it. It’s communicable, but not very: symptoms include extreme lassitude and a mild fever for several days, a brightly glowing rash that turns into a brightly glowing scar, and the permanent acquisition of both a psionic talent, and minor psionic abilities/perks. Garish Tattoo is never fatal on its own, but somebody with a compromised immune system might not survive the experience. There are seven recognized strains of Garish Tattoo: contracting one form of the disease immunizes you from the others.
Continue reading GURPS disease/package: Garish Tattoo. [GURPS 4E]