Cats may be among the most beloved pets, but a recent research report says they can make their owners mentally ill. According to the researchers, a parasite present in feline feces can be passed on to humans, resulting in mental illness, including schizophrenia.

Feline feces contains a parasite called Toxoplasma gondii (T. gondii). According to CBS News, it is one of the most common parasites present in developed nations. The parasite can be passed on from cats to humans.

It is estimated that nearly 60 million Americans may be infected with the parasite. CBS News reports that people with a weak immune system may even have taxoplasmosis due to the infection. This illness may lead to blindness, miscarriages and developmental disorders in fetuses. In the worst scenarios, it may lead to death.

The latest research has extended the effect of T. gondii to the increased risk of schizophrenia and bipolar disorder. During the study, the team established a link between people who owned a cat early in life and were later diagnosed with mental illness.

The researchers found that nearly 50 percent of the people who owned a cat in childhood were diagnosed with mental illness later in life. Thus, the team concluded that such people are at an increased risk of developing schizophrenia and bipolar disorder at a later stage.

“Cat ownership in childhood has now been reported in three studies to be significantly more common in families in which the child is later diagnosed with schizophrenia or other serious mental illness. In schizophrenia, the evidence of an association with T. gondii is overwhelming,” report the authors.