According to several epidemiologic studies, it appears that infectious agents can sometimes become triggers of schizophrenia. Infecting animals with Toxoplasma gondii can cause dramatic changes in behavior and alters neurotransmitter function.
But on the other hand, triggering an acute infection in humans with T. gondii, or the cat virus as it was dubbed, has the ability of producing psychotic symptoms resembling those present in patients suffering from schizophrenia.
Two more studies were conducted whose results showed that being exposed to cats during childhood increased the risk factor of developing schizophrenia.
Researchers have been studying this matter extensively ever since 1953; eighteen out of 19 control studies on T. gondii antibodies in patients with schizophrenia and other severe mental illnesses reported that the affected persons presented a higher level of antibodies. In 11 of those 18 studies, the difference was deemed statistically significant.
During the development of the studies, researchers noticed there might be a geographic connection between T. gondii’s preponderance and the rates of schizophrenia, but they could not pinpoint it.
For example, in France, where the number of confirmed Toxoplasma-infected persons is rather high, reports also show that first-admission rates of schizophrenia patients are roughly 50 percent higher than those in England. In rural areas of Ireland, T. gondii rates have also gone through the roof.
In order to gather more data on this medical matter, Dr. Robert H. Yolken, the head of the Stanley Laboratory at Johns Hopkins University, put together a team of colleagues and reviewed military medical records.
They showed that soldiers who received a schizophrenia diagnosis had doubled their chances of presenting signs of Toxoplasma infection in blood samples, unlike the other soldiers.
Schizophrenia is a neuro-psychiatric condition whose causes are still a mystery, a disease that affects roughly 1 percent of the adult population in Europe and the United States. Researchers have established that genetic factors have an important role, as schizophrenia seemed to occur much more in family members of affected persons.
T. gondii is an intracellular parasite whose definitive hosts are felines, particularly cats. Intermediate hosts, however, are not immune to its infection, including humans. T. gondii is known to cause abortions and stillbirths in mammals, and sometimes it infects muscle and brain tissue.
Most cases of human infections develop after eating undercooked meat or by coming in contact with cat feces. Modes of transmission, however, are prone to change in different populations.
There are plenty of factors playing a role in individual response to Toxoplasma infection: immune system status, timing of infection, and the genetic material of the host are some of them.
Young children should have limited access to cats, which is one of the wisest ways of preventing Toxoplasma infection. Dr. Torrey, the leading researcher of this study, strongly advises parents not to expose their young children to pet cats.
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