Parasite Makes Rats Sexually Attracted to Cat Urine

Posted on August 18, 2011

Toxoplasma gondii in mouse ascitic fluidResearchers have found that the parasite Toxoplasma gondii makes rats sexually attracted to cat urine. This is obviously something that could be extremely dangerous and potentially fatal for the rat, but very good for the parasite.

The researchers write in PLoS One, "Since the protozoan Toxoplasma requires the cat to sexually reproduce, this change in host behavior is thought to be a remarkable example of a parasite manipulating a mammalian host for its own benefit."

The rats' fear of other predators does not change when they are infected with the parasite. The researchers say the rats with Toxoplasma gondii may still fear cat urine, but the infected rat's sexual desire for the cat urine could be overwhelming its natural fear.
Interestingly, Toxoplasma increased MEApd activity during cat urine exposure to levels mimicking uninfected rats during female exposure (Figure 1F). This suggests that the specifically increased magnitude of MEApd activity in male Toxoplasma infected rats is biasing the processing of the cat urine toward the sexual, 'reproductive' pathway (Figure 2D). Plausibly, this shift is altering the salience of the cat urine stimuli and mitigating the defensive response by creating, in its stead, a competing attraction to the cat urine.
The researchers also say that one-third of all humans are infected with Toxoplasma gondii. Ingestion of undercooked meat from infected livestock and cat ownership are two factors driving human infection. The researchers say some recent studies have found a link in humans between Toxoplasma gondii and an increased risk of schizophrenia and obsessive compulsive disorder.

The research paper was published here on PLoS One.

Photo: Toxoplasma gondii in mouse ascitic fluid/CDC/ Dr. L.L. Moore, Jr.