OBJECTIVE:

To compare the prevalence of Toxoplasma infection between the first-episode schizophrenia and the controls and to compare the clinical features between the Toxoplasma-seronegative and Toxoplasma-seropositive patients with schizophrenia.

METHOD:

The rate of serum reactivity to Toxoplasma in 600 schizophrenia, 600 affective disorders, and 400 controls was investigated. The clinical symptoms of the schizophrenia patients were scored and compared.

RESULTS:

The rate of IgG antibody, not IgM in the schizophrenia patients, was higher than the control groups, and the odds ratio of schizophrenia associated with IgG antibody was 2.22-5.12. The affective disorders did not differ in the rate of IgG or IgM antibody from the normal or the physical disease control. The seropositive schizophrenia patients had higher scores on the positive subscale and three components of Positive and Negative Symptoms Scale than the seronegative patients.

CONCLUSION:

This study lent further weight to the hypothesis that exposure to Toxoplasma may be a risk factor for schizophrenia.