Odds and Ends
Take the wheel
6 7, 11:48pm
The brain isn't affected at all in humans ^^'
As I said, parasites are optimized for a specie in particular, and usually when it ends by accident in another animal, it doesn't end well for it. What happens in most cases is that the parasite's cycle is stopped, and it cannot evolve or reproduce. What happens when you get this parasite is that your inmunity system is mobilized to Attack it, the poor parasite during this time is completely lost because obviously human's bodies is different that rat and it cannot go into the brain by the path that was planned for the rat. Your inmunity system attacks and destroy the parasite causing milds colds symptoms, and antibodys are created to protect the system even quicker next time the parasite come into our system.
It is those antibodies that medecine detects, but it is only indicative of if you have ever been in contact or not wth this parasite, Nothing more.