Back in 2012, we reported on Toxoplasma gondii, a very common parasite carried by cats (as well as unwashed vegetables and undercooked meat) that affects humans. At the time, scientists were indicating the possibility that this parasite may cause mental disorders, among other things, in humans. According to CBS News, “the Centers for Disease Control and Prevention estimates more than 60 million people in the U.S. may have it.”
It is, however, asymptomatic. Illness appears only in those who have weakened immune systems. The illness, toxoplasmosis, causes blindness, flu-like symptoms that lasts weeks, fetal development disorders, miscarriages, mental disorders such as bipolar disorder and schizophrenia and death, CBS News reports.
Over the last 30 years, Dr. Robert H. Yolken of the Johns Hopkins University School of Medicine’s Stanley Laboratory of Developmental Neurovirology and the Stanley Medical Research Institute’s E. Fuller Torrey have been studying the connection between schizophrenia and T. gondii. The two researchers published a recent study in Schizophrenia Research in which two earlier published studies linking having a cat in childhood with developing schizophrenia later on were compared with an unpublished mental health survey conducted in 1982. The results indicated that those who had cats as children were at a higher risk of developing mental disorders.
“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 another serious mental illness,” Yolken and Torrey reported in a press release, CBS News reports.
In a recently published study in the Acta Psychiatrica Scandinavica journal, A.L. Sutterland and colleagues of the Academic Medical Centre’s Department of Psychiatry in Amsterdam did an analysis of 50 published studies confirming the connection between mental disorders and T. gondii. Their results showed that individuals who had been infected with T. gondii were nearly twice as likely to develop schizophrenia as those who had not been infected with the parasite.
“In schizophrenia, the evidence of an association with T. gondii is overwhelming,” Sutterland and colleagues said in a press release, according to CBS News. “These findings may give further clues about how T. gondii infection can possibly [alter] the risk of specific psychiatric disorders.”
Another study also states that exposure to the parasite could affect a child’s reading skills and memory scores, The Telegraph reports.
“The results suggest that Toxoplasma gondii seropositivity is associated with poor reading performance and impaired verbal memory… Future longitudinal studies are needed to confirm these findings and research could include trials to confirm a possible efficacy of vitamin E supplementation in improving cognitive impairment hypothetically associated with the infection,” University of Iowa scientists wrote, according to The Telegraph.
Does this mean researchers are suggesting we give up our cats and never let our children play with one? Of course not.
Indoor cats are far less likely to become infected with the parasite than outdoor cats. Torrey told CBS News that preventative measures such as keeping your cat indoors and covering a child’s sandbox when he’s not using it should be taken. The CDC, according to CBS News, “recommends changing the cat’s litter box daily, since T. gondii does not become infectious until 1 to 5 days after it is shed in feces. In addition, avoid feeding cats raw or undercooked meat.”
Simple enough, right? Health officials do still highly stress that pregnant women not change litter boxes, as t. gondii is a high risk to unborn children.