Intestinal Parasites is a risk that is obtained from eating meat of carnivores (wolves, bears) in The Long Dark.
Curing of Intestinal Parasites
Once infected with an Intestinal Parasite, then you have to take 10 Doses of 2 Antibiotics or 1 Reishi Tea, at a rate of 1 Dose per day, before the infection is removed. During this time, you'll receive more fatigue (less stamina) and your max life will be reduced by 1% per day and recurring until the infection is removed.