Wendigoism is a rare monstrism caused by a virus that affects animals and peoples alike. It has no cure or treatment, although prevention is easy.
Wendigos suffer from many symptoms caused by a virus. Notably, they start to crave flesh of their own species, being compulsivelly cannibalistic. In fact, they become strongly dependent on this food source, being unnable to properly extract nutrients from other meats or from vegetables and such. They still drink water, nonetheless.
Another symptom is gigantism. As wendigos eat, their bodies grow. This often grants them spindly looks, although their feet may be crushed by their own weight and reformed into shapes that better carry their massive weight. The skin is often stretched and torn, bleeding. Their blood if filled with a rot-smelling pus.
Wendigos are remarkably powerful. Their long muscles are strong, and large ones can lift other people. Their regenerative abilities excel those of vampires and many other monsters. In fact, even if their bodies are completelly dissociated, a piece of their heart will eventually regrow the whole body, even if it is smaller than before. The heart must be burned completelly and the ashes must be laid upon a hot silver plate. After some hours, they will enter permanent degenerate consciousness. Silver weapons are really good at inflicting lasting wounds, anyways. These monsters are also clever, often more than their former healthy selves. They loose the gift of speech a few days after being transformed, however. Somehow, they may still be able to understand any languages they knew.
Many wendigos also have a very powerful sense of hearing, being able to understand whispers from many meters. As such, loud noises are often used to annoy and distract wendigos.
The wendigo monstrosity agent (WMA) has 3 forms, which are related to the stage of infection and the spread of the disease. Wendigos bear the WMA-3 or active form, which causes the symptoms. Its sweat, phlegm, urine, feces and saliva have the WMA-1 or spreading form. The WMA-1 can stay on skin and mouths of healthy patients for years. When a patient bearing the WMA-1 dies, the virus turns into its penultimate form, the WMA-2 or latent form, which may be ingested by a patient, which will hence become a wendigo with the WMA-3.
This means that a whole population of people or animals may have the virus in the latent form and it won't express itself. Once someone commits cannibalism, however, they will turn into a wendigo. The virus can adapt to infect different creatures while in the active form, but it will only become an active virus if the patient actually eats the flesh of its own species.
Wendigos are known to purposefully spit, urinate and defecate on water sources as to infect them.