If it is not controlled by the immune system, it causes general neurological disorder, potentially severe (Parkinson-like, dementia, brain damage), and can start to invade other organs. This is uncommon except in people with serious immune dysfunction.

When an infection is latent, it's normally described as asymptomatic. But there is some reason to think, it might subtly affect humans neurologically in a similar way to how it seems to affect other mammals, like the wolves in this article. But this is controversial.