A single-celled organism, called Toxoplasma gondii, will lead to some unfortunate events, if a rat becomes infected with the parasite. While the rat may feel unusually confident and attracted to its number-one enemy, the story won't have a fairy tale ending.
Of course rats normally avoid cats at all costs and even shy away when near a feline's urine. Toxoplasma gondii reverses a rat's nervousness and actually allows them to become attracted to cats. For a rat to be attracted to a cat, we all know it's not a good thing, especially since cats won't pick up the parasite themselves, or find themselves being attracted to the rat. The parasite makes it easier for a cat to chow down on its favorite little snack allowing the organism to reproduce--Toxoplasma only reproduces in cats.
When a rat becomes infected with Toxoplasma, a part of the rat's brain which is normally engaged in sexual attraction becomes activated. Instead of running away when smelling cat urine, a rat will instead seek the cat out.
Toxoplasma may be a rat's worst enemy, but it can also affect other animals and even humans. Toxoplasmosis can be developed in humans, so steering clear of cat droppings is even more important than one would think.
Thankfully, however, toxoplasma will not affect human behavior in the same way it affects a rat's, so nobody should worry about catching the parasite, and like a rat, chase out danger.
Source: NY Times
Photo credit: puellakas