Sleepwalker Infected, for 5e and Tales of the Valiant

The Sleepwalker infected are innocent victims afflicted by a horrific variety of the 'sleeping disease'. Not only are they subject to the aches, pains, fatigue, and eventually coma of that disease, once they succumb, the disease keeps them alive, utilizing photosynthesis to feed itself and them, making them drink water and sometimes even eat dirt. They will also eat the flesh of slain victims, though the parasite that causes the disease doesn't actually make them try to kill others . . . just bite them to transfer the infection.

The Green Plague

The disease, carried by biting flies and the Sleepwalker infected, first shows symptoms after about 12 hours. The victim has a fever, headache, joint and body aches, with mounting fatigue. Once the disease is fully manifested, the infected creature is poisoned until the disease is cured. Every 12 hours that elapse, the infected creature must succeed on a DC 12 CON save or take a level of exhaustion. While infected, they must make a DC 12 Constitution save at the beginning of each long rest, or receive no benefit, as their sleep is badly disturbed. With each level of exhaustion, the symptoms worsen, and the victim's skin begins to turn green. Once they reach three levels of exhaustion, they begin to fall asleep at random times regardless of what they are doing (DC 12 Con save to resist). While asleep at this stage, they may sleepwalk, but will not yet be aggressive. Once they reach 6 levels of exhaustion, they do not die, but instead enter a comatose state, ambulatory and hunting during the day, resting at night. They have become Sleepwalker infected, at this point. The disease is highly virulent and resistant to treatment. Some rare herb or combination thereof might be able to cure it, alongside a DC 20 Medicine or Herbalism toolkit check by the person treating the disease, but as far as magic goes, greater restoration is required to cure the affliction. The treatments can be effective at any stage, even after the victim has become a full Sleepwalker.

Note that animals can catch and transmit the Green Plague as well.

sheet (and science) here: https://www.patreon.com/posts/106574535