Understanding the role of parasites as a threat to the animal’s health or even life is critical for management of endangered wildlife populations ranging in a restricted area. In the past years, we observed cases of mountain gorillas chronically wasting, sometimes ending in death, and the potential role of nodular worms as a cause of this illness has been suggested based on post-mortem examinations. Using a combination of classic techniques such as microscopy and the state-of-art high through-put sequencing we will investigate the helminth and microbial communities inhabiting the gut of both healthy and ill gorillas to clarify the role of helminths, especially nodular worms, in this clinical disease. In addition, we will evaluate the effect of anthelminthic treatment on the occurrence and recurrence of the disease’s symptoms by regular observations of the treated animals. We will provide scientifically based evidence for future treatment decisions and successful management of gut parasite infections in mountain gorillas, approach that can be transferred to other wildlife species.