Cats. We love them. They sorta, kinda like us but likely won't come when called. It's a love/tolerate relationship more than 9,000 years in the making.
Back in 2012, however, our special bond with cats was rocked when The Atlantic reported on a common cat parasite that could mess with our brains. Called Toxoplasma gondii, or T. gondii, the parasite infects up to a third of the world's population. Humans picked up the parasite "by coming into contact with cat feces, drinking contaminated water or eating unwashed vegetables or undercooked meat."
Because cats act as the sole reproductive host for the parasite, they may inadvertently pass it along to their human companions through feces or infected surfaces.
While pregnant women have been warned about T. gondii in cat litter for decades (infection can cause brain damage and vision loss in infants), this new revelation painted the parasite as a hidden threat to the rest of the population as well. Jaroslav Flegr, an evolutionary biologist at Charles University in Prague who studied the parasite, said its impact on the human brain could be responsible for everything from increased mental disorders to depression and even death.
“Toxoplasma might even kill as many people as malaria, or at least a million people a year,” Flegr told The Atlantic.
Suddenly, cats were not the indifferent cuddly fur balls we thought they were.
New research from the University College London puts the brakes on the Internet's overblown fears that T. gondii can irrevocably alter human behavior. The study, published in Psychological Medicine, looked at nearly 5,000 people born in 1991 or 1992 who were followed through age 18. Researchers found no link between cat ownership and psychotic symptoms.
"The message for cat owners is clear: There is no evidence that cats pose a risk to children's mental health," said study author Dr. Francesca Solmi, of University College London Psychiatry.
In a February 2016 study out of Duke University, researchers studied nearly 900 New Zealanders (28 percent of them infected with T. gonddi) found little evidence of a connection between the parasite and an increase in brain disorders.
"Our results suggest that a positive test for T. gondii antibodies does not result in increased susceptibility to neuropsychiatric disorders, poor impulse control or impaired neurocognitive ability," the team conclude in the study, published in PLoS ONE. "This is, to our knowledge, the most comprehensive assessment of the possible link between T. gondii infection and a variety of impairments in a single cohort."
The study did find a very slight uptick in the number of suicide attempts by the group infected with T. gondii, backing up previously published findings in this area. For all other areas, however, the impacts were insignificant. "We found no link to schizophrenia or its associated neuropsychological deficits in our cohort," they added.
While this study is a promising and reassuring addition to our insights about T. gondii, the researchers admit that more work needs to be done to fully understand the impact it may have on our lives. To that end, here's how to protect yourself from T. gondii:
- Keep your cat indoors.
- Don't feed your cat raw or undercooked meat.
- Wear gloves while changing the litter box and while gardening.
- Change your cat's litter box daily and wash your hands afterward. Use boiling water to clean litter boxes and allow the water to sit for 5 minutes to kill the parasite.
- Cover sandboxes when they're not in use so cats don't defecate in them.
- Cook meat until it's well done.
- Wash fruits and vegetables thoroughly with clean water.
Editor's note: This story has been updated since it was originally published in February 2016.