I have seen that the virus makes the rat like the cat insted of running away in fear, the virus can also infect humans though what efect if any it has on our minds is not known.
That's Toxoplasma Gondii. It's pretty much endemic to humans and make men become grumpy curmudgeons and women promiscuous. It is also implicated in schizophrenia (but this is debated at this point in time).