I got some snakes in about two years ago that had an amoeba infestation and i don't wish that on anyone. They appeared healthy and continued to eat but their feces looked and smelled horrible and they just kept losing weight and then towards the later stages they started passing blood. I managed to save a few by treating them with flagyl. The thing is these guys that catch these snakes for resell alot of times don't care about the animals so they will throw tons of them in the same tank so parasites and diseases spread to all of them.