Whats up with Yuko puking up blood?

I thought that beating SS2 would have told me this but all that Yuko's ending told me was that it snows because of him making an ice sculpture. Any way... can someone tell me the story behind the blood.

Um, do you mean Ukyo? He has Tuberculosis.

So does Zantetsu, and that nunchuck wielding bastard in Soul Edge.