parasites can live off of blood and tissue. There isn't an area of the body that they cannot infest. Read parasite Rex and you will understand that parasites control many living things. They can alter an intermediate host's behavior enough so that the the intermediate host will get eaten by the final host. So the parasite can become an adult and start multiplying. Procreation is the biological imperative.
So I don't disbelieve anyone on this forum and their stories about what shows up.