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Have an affinity for cats? It might just be the toxoplasmosis talking

Toxoplasmosis Life Cycle

Earlier this week, Michigan Radio's Rina Miller reported on an MSU study that links a parasite found in cat stomachs and undercooked meat to suicides.

That may be just the beginning for Toxoplasma gondii.

The infection it can cause in humans, called toxoplasmosis, appears innocent enough.

Many cases exhibit no symptoms and typically require no treatment.

However, WNYC's RadioLab produced a show in 2009 that demonstrates how the latent infection is being studied in relation to a bizarre set of behaviors including a 19th century "cat craze," slow reaction times, dangerous driving, and even neurological disorders like schizophrenia.

Toxoplasmosis spreads to humans through the consumption of undercooked meat, accidental ingestion of feline fecal particles and through blood-to-blood contact, including from pregnant women to their fetuses.  The CDC estimates that 60 million people have had toxoplasmosis in the United States, though most are unaware they are infected.

Humans, says Toxoplasma gondii expert Robert Sapolsky, is not the intended host for the parasite, which prefers cats or the rodents they consume.  This is because it appears the parasite can only sexually reproduce within a cat's stomach.

When a rodent consumes the cat feces, Sapolsky says,

"Toxo starts off in the stomach of the rodent. It takes about six weeks to migrate up to the brain, and once it's there, it finds this particular region called the amygdala, which is like command central for fear and anxiety and terror. It also finds this other region right next door where a very different emotion lives-- sexual arousal. And what Toxo seems to be able to do, is to somehow cross the wires."

This renders cats attractive as opposed to terrifying to infected rodents, which makes them easy targets for cats.  In this way, the parasite returns to its preferred host in the cat's stomach.

The notion that "toxo" can produce a similar attraction between humans and cats, says Sapolsky, isn't out of the question.

You can listen to the RadioLab clip called "The Scratch" here:

-Elaine Ezekiel, Michigan Radio Newsroom

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