Mara infected

"Not like him," Mara replied, somewhat softly, and the sudden weakness in her voice reminded Leia and Jaina that Mara, despite her nearly constant bravado and over-abundance of energy, was seriously ill, with a strange and thankfully rare disease that had killed dozens of others and against which the best doctors in the New Republic had proven completely helpless. Of those who had contracted the molecular disorder, only Mara and one other remained alive, and that other person, being studied intently on Coruscant, was fast dying.
-New Jedi Order: Vector Prime