Feral Wasting Syndrome

It starts with hunger. Not the kind that a meal fixes, but a gnawing, bottomless appetite that no amount of food can satisfy. The afflicted eats constantly and gains nothing. The Infection inside their body has become overstimulated by foreign animal pathogens, and it is burning through every stored resource the host possesses in a runaway feedback loop that will not stop. Fat goes first. Then muscle. Then thought.
  Feral Wasting Syndrome enters through the things survivors take for granted: water shared with infected wildlife, meat from diseased animals that was not cooked thoroughly enough, contaminated ingredients that made it into the communal kitchen. The pathogens interact directly with the host's Infection, and once that interaction begins, it accelerates beyond any natural limit. The body regresses. Speech patterns degrade from full sentences to clipped fragments to grunts. Irritability sharpens into animalistic reflexes. Eyes go glassy. The afflicted becomes increasingly sensitive to light and sound, snapping toward movement with the sudden focus of a predator rather than a person.
  As cognitive function erodes, the disease strips away what separates a survivor from the beasts outside the walls. Trained skills become inaccessible. Language dissolves. Emotional recognition fades until the afflicted cannot distinguish between a friend offering help and a threat to be driven off. Darkened veins and erratic twitching mark the Infection's visible fight to sustain what is left of the nervous system. By the severe stages, the host exists in a state of feral aggression punctuated by tremors and convulsions, the body breaking down as fast as the mind. Terminal collapse comes with seizures and total motor failure as the Infection consumes nearly all internal tissue in a final, failed attempt to keep its host alive. Post-mortem examination reveals a desiccated shell, wasted to bone and sinew.
  Treatment at early stages involves simple hydration therapy. Later stages demand increasingly invasive intervention, from nervous system surgery and hallucinogenic resets to morgue-based tissue replacement. Death prior to the terminal stage reduces the disease by one stage, a small reprieve. Death at the terminal stage returns the afflicted to Stage 1 through the Mortis, which means the disease persists even through the cycle of death and rebirth. It is a patient disease, FWS. It is content to start over and begin wasting again.