This is my opinion. I form my opinion from many years of reading these reports. I have noticed a trend: Australian scientists looking for ways to criticise the domestic cat for carrying the zoonotic disease toxoplasmosis.
From time to time, Australian scientists like to get together to hatch a plan to denigrate the domestic cat with the long-term intention of reducing cat ownership in Australia in order to protect native wildlife from predation by cats allowed outdoors unsupervised.
And I’m going to report on an instance of this which has currently hit the news media headlines. It concerns a review report which means that Australian scientists have reviewed previous reports of published studies on scientific journal websites.
And in this instance, they reviewed studies concerning the Toxoplasma gondii parasite which is carried by the domestic cat for a short time in their lives and which is passed in a cat’s faeces as oocyts (eggs) which in turn can be ingested by people thereby transferring toxoplasmosis from the cat to people (zoonosis).
It has been proposed by some scientists in these previous studies that toxoplasmosis can cause schizophrenia in people. And this is where the scientists denigrate the domestic cat. If they can “prove” that cats give people schizophrenia it’s going to result in at least some cats being relinquished to shelters or simply abandoned on the street somewhere.
But the issue here is that these early research papers are very dubious. It seems to me that in many instances the researchers have an ulterior motive or a hidden agenda which is to criticise a domestic cat to reduce cat ownership.
And it’s reported that Australian researchers analysed 17 previous studies (from an initial selection of 1915!) published over the past 44 years in 11 countries. And the lead researcher, John McGrath, a psychiatrist, from the Queensland Centre for Mental Health Research, concludes, “We found an association between broadly defined cat ownership and increased odds of developing schizophrenia-related disorders”.
The theory that schizophrenia in people can be caused by cat faeces come from a 1995 study. But it should be stressed that these previous studies are not particularly solid in their conclusions. Not all studies have found this association.
It is said that the new analysis of 17 studies found “a significant positive association between broadly defined cat ownership and an increased risk of schizophrenia-related disorders”.
An important point is that of the 17 studies, 15 were “case-controlled studies”. The studies do not prove cause and effect. They just look at things and it is possible to come to the wrong conclusions.
And it is admitted that a number of the studies were of low quality. However, despite this admission, the researchers concluded that their report supports an association between cat ownership and schizophrenia-related disorders.
“Our findings support an association between cat exposure and an increased risk of broadly defined schizophrenia-related disorders; however, the findings related to PLE as an outcome are mixed. There is a need for more high-quality studies in this field.”Study conclusion
What I have not seen is a reference to the much more common cause of toxoplasmosis in people namely the eating of unpasteurised milk, poorly prepared raw foods containing oocysts. It’s far more common to get the disease from that source than from cats.
My conclusion is that people should not take this report with any seriousness. I don’t want to be biased or criticise the findings of this research but it seems to me to be scaremongering and very dubious science. I’m yet to see some solid science on the domestic cat being a danger to people because it can transfer toxoplasmosis to them and thereby cause schizophrenia-related diseases in these people.
John J McGrath, Carmen C W Lim, Sukanta Saha, Cat Ownership and Schizophrenia-Related Disorders and Psychotic-Like Experiences: A Systematic Review and Meta-Analysis, Schizophrenia Bulletin, 2023;, sbad168, https://doi.org/10.1093/schbul/sbad168
Infographic on toxoplasmosis
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