Introduction: Toxoplasma gondii can stay dormant as bradyzoites in tissue cysts in the central nervous system. There is accumulating evidence about the possible causal relationship between latent toxoplasmosis and schizophrenia. The aim of this study was to investigate, the rarely studied, association between various clinical aspects of schizophrenia and seropositivity against Toxoplasma gondii.

Materials and Methods: We selected 94 patients with schizophrenia, and investigated the seropositivity rate for toxoplasmosis by ELISA. Clinical parameters of schizophrenic patients such as illness type and status, clinical course, awareness of the illness, need for electroconvulsive therapy (ECT) were compared with their serological status.

Results: Anti-T. gondii IgG antibodies were detected in 43 (45.7%) of schizophrenic patients. Chronic patients had a rate of 32 (72.3%) seropositivity whereas 9 (22%) of patients with partial remission showed evidence of latent toxoplasmosis. Of continuous patients, 35 (81.4%) were found to be seropositive and this rate was significantly higher than the other groups. Latent toxoplasmosis was detected significantly higher in 36 (72%) of the patients who lack awareness of schizophrenia than the patients who were aware of their illnesses (7, 15.9%). Among ECT performed patients, 38 (70.4%) were seronegative while only 5 (12.5%) of the ones who had never been treated with ECT were free of antibodies (p<0.001) .

Conclusion: Our results put forth the possibility of latent toxoplasmosis to have a negative impact on the course of schizophrenia and treatment response of schizophrenic patients.