The Centers for Disease Control and Prevention (CDC) recently denied knowing of “a virus or condition that would reanimate the dead (or one that would present zombie-like symptoms),” after a series of instances of cannibalism across the country were reported, but remains silent about the effect of zombie-inducing parasites that live in human brains.
A 2008 piece by Discover Magazine entitled, “Zombie animals and the parasites that control them,” named a single-cell parasite primarily found in cats, the Toxoplasma gondii — which alters the brain-chemistry of rats to make them more likely to seek out cats — as one such parasite.
The Toxoplasma “thus makes a rat more likely to be killed and the parasite more likely to end up in a cat — the only host in which it can complete the reproductive step of its life cycle,” Discover reported in a separate piece.
The parasite can also live in the brain cells of thousands of other warm-blooded animals, including humans. The Toxoplasma, when living inside humans, is linked to causing significant changes in behavior, including neuroticism, increased aggression and schizophrenia.