A common parasite found in cats and undercooked meats could pose a bigger risk to humans than previously thought.
It's called toxoplasma gondii. Up to 20 percent of people in the U.S. carry it.
A new study from Michigan State University finds the parasite can cause inflammation in the brain, which can produce harmful metabolites that can damage brain cells.
MSU professor Lena Brundin says the study linked the infection caused by the parasite to depression and more.
"People who are positive for toxoplasma, they are seven times more likely to be a suicide attempter, so that was the risk analysis we did in our study," Brundin says.
She says previous research found signs of inflammation in the brains of suicide victims and people suffering from depression.
Brundin says nearly 37,000 Americans committed suicide in 2009.
"If we could identify those people infected with the parasite, it could help us predict who is at higher risk," Brundin explains.
Brundin's research shows a reduction in the brain's serotonin might be a symptom rather than the root cause of depression.
She says the important message is that researchers are working to develop new treatments to prevent suicide.
She says people don't need to be afraid of cats, but should use simple precautions, like hand washing after cleaning a litter box.
However, pregnant women and people with compromised immune systems are cautioned to avoid handling litter boxes.