Study Links Cat Parasite To Mental Illness In Humans

Could having cats increase your risk of mental illness? New research suggests it may.

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Latest research indicates that cat exposure in childhood may be a risk factor for developing mental disorders. leftfieldphotography/iStock/Thinkstock

There’s nothing like kitty kisses when you’re feeling down, but new research suggests having a cat may put you at risk of developing a mental illness.

Cats carry a parasite called Toxoplasma gondii or T. gondii, which can be transferred to humans (and other warm-blooded species). Infected individuals may show no symptoms at all, but it can cause the following in those with weaker immune systems: flu-like symptoms, miscarriages, fetal development disorders and eye disease.

Previous studies also have linked T. gondii infection (also called toxoplasmosis) to mental disorders. Now, two recent studies provide further evidence of this association, CBS News reports.

In the most recent study, published this month in Schizophrenia Research, researchers compared the results of two previous studies that suggested childhood cat ownership is a possible risk factor for later developing schizophrenia or other serious mental illness with an older, unpublished questionnaire on mental health. The analysis suggested that “cat ownership in childhood is significantly more common in families in which the child later becomes seriously mentally ill.”

In the second study, published in Acta Psychiatrica Scandinavica, researchers analyzed the findings of 50 published studies. They found that those infected with T. gondii are almost twice as likely to develop schizophrenia, CBS News reports. They also found a link between T. gondii infection and addiction and obsessive-compulsive disorder.

The cat-carried parasite T. gondii can be transmitted to humans by cat feces. Ysbrand Cosijn/iStock/Thinkstock

The cat-carried parasite T. gondii can be transmitted to humans by cat feces. Ysbrand Cosijn/iStock/Thinkstock

Cats infected with T. gondii excrete millions of infected eggs, or oocysts, in their feces, which can remain in soil or water for years, according to CBS News.

“Children can be protected by keeping their cat exclusively indoors and always covering the sandbox when not in use,” E. Fuller Torrey, a researcher who worked on the study published in Schizophrenia Research, said in an email to CBS News.

The U.S. Centers for Disease Control and Prevention also suggests the following:

  • Change your cat’s litter box daily, as T. gondii does not become infectious until one to five days after it is shed in feces.
  • Avoid feeding cats raw or undercooked meat.

Pregnant women should avoid cleaning litter boxes or wear disposable gloves and wash hands thoroughly with soap and water afterwards.

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