Parasite Spurs Rat Sexual Frenzy

The parasite Toxoplasma gondii furthers its transmission by making rats go wild for the scent of cat urine.

Aug 19, 2011
Tia Ghose

A rat gets cozy with a kittenFLICKR, TLINDENBAUM

The cat parasite Toxoplasma gondii lures infected rats to their feline predators by making the rodents sexually aroused by cat urine, according to a new study in PLoS One.

For over a decade, researchers have known that Toxoplasma gondii, which forms brain cysts, furthered its transmission by making the otherwise sensible rats it infected approach their feline predators, who would then eat them and acquire the parasite themselves. But how the parasite achieved this feat was a mystery.

Researchers from Stanford University found T. gondii hijacks the arousal circuitry that is activated when a rat encounters a sexually receptive female. While the circuitry that makes rats petrified of their predators still fired, the attraction signal overpowered the message. The researchers aren’t sure how the sexual circuitry gets rewired to respond to the cat urine.

Roughly 2 billion people are carriers of T. gondii, although it’s usually harmless and only causes problems in immuno-compromised people and pregnant women, The New York Times reports. So far, there’s no evidence that T. gondii makes infected cat owners feel more frisky towards their pets.