There is a parasite, Toxoplasma gondii that is found in cat feces. Serological studies suggest that almost one third of the global population has been exposed to and may be chronically infected with this parasite. Infection is typically asymptomatic in healthy adults. T. gondii has been shown to alter the behavior of infected rodents in ways thought to increase the rodents’ chances of being preyed upon by cats. Because cats are the only hosts within which T. gondii can sexually reproduce to complete and begin its life cycle, such behavioral manipulations are thought to be evolutionary adaptations to increase the parasite’s reproductive success. Although numerous hypotheses exist and are being investigated, the mechanism of T. gondii–induced behavioral changes in rodents remains unknown. A number of studies have suggested subtle behavioral or personality changes may occur in infected humans, and infection with the parasite has recently been associated with a number of neurological disorders, particularly schizophrenia. However, evidence for causal relationships remains limited. The phenomenon of the “crazy cat lady” has been attributed to severe infection with T. gondii in the female brain. It must be noted that their is no direct evidence or data to support this “attribution”, and thus it is wildly speculative.
I love cats, so does my family. Since as early as I can remember we have had at least one, and usually more than one cat living in and around my household. As a research microbiologist I had always been fascinated by the phenomena of parasitism. Although I ended up specializing in bacteriology I followed closely the most ground breaking research in the field of parasitology. When the connection between T. gondii and cat feces was first hypothesized I became obsessed with learning everything I could about this strange parasite and its relationship with our friendly felines. The implications for mental health seemed especially interesting. In addition to its supposed role in schizophrenia, T. gondii has been linked (albeit weakly) with increased risk for anxiety, depression, and a host of other mental afflictions. Higher rates of substance abuse among cat owners, especially with cats that are infected with T. gondii, have also been shown. I suffer from severe anxiety and my sister has had numerous mental health issues. Interestingly my parents do not appear to be affected and are very healthy both mentally and physically. I would note however that neither of my parents grew up with cats in the household. It may be there is an age of exposure component to the pathology of conditions (potentially) caused by T. gondii. As I got older my mental condition continued to deteriorate. Chronic bouts of anxiety and depression became more frequent. At the same time I experienced periods of severe mania usually accompanied by habitual substance abuse. Somehow I managed to keep my job in research as I drifted in and out of treatment programs and rehabs. Through it all cats were my constant companions. After I was arrested for a murder I certainly committed it all became clear. I was not to blame. The parasites had corrupted my brain. I don’t blame my cats. Never blame the cats.
Author’s postscript: Obviously this entire story is fictional along with many of the so called “facts” about T. gondii that are presented. Each has at least a veneer of truth and certainly seem plausible which is one of the reasons I liked them so much for this story. For the record the mental and physical health conditions attributed to myself and members of my family are also (almost entirely) fictional.