Mara infection symptom

"What about Mara?" he asked seriously. "They'll be back soon, and from what I hear, things didn't go very well." That hit home to Luke, a reminder, as everything seemed to be a reminder, that his beloved wife was not well. The best doctors in the galaxy were shaking their heads helplessly, able to do nothing but watch as something inside Mara continually altered her molecular structure. No medicine, no therapy, had come close to treating the rare disease, and only her own internal strength, her use of the Force, was somewhat keeping it in check. Those others who had contracted the disease had not been so fortunate.
-New Jedi Order: Vector Prime