Toxoplasmosis is a lifelong parasitic disease that appears to be associated to schizophrenia. However, no distinguishing attributes in Toxoplasma‐infected schizophrenia patients have been described as yet.

We searched for differences in symptom profile, cognitive performance and treatment response between 194 Toxoplasma‐free and 57 (22.7%) Toxoplasma‐infected schizophrenia patients treated in Prague Psychiatric Centre between 2000 and 2010.

Infected and non‐infected patients differed in severity of symptoms (P = 0.032) measured with the Positive and Negative Symptom Scale (PANSS). Infected patients scored higher in positive subscale of PANSS, but not in the general and negative subscales. Infected men scored higher also in Total PANSS score, and negative, reality distortion, disorganisation and cognitive scores. Higher PANSS scores of positive, negative and disorganised psychopathology were associated with the lower titres of anti‐Toxoplasma antibodies suggesting that psychopathology deteriorates with duration of parasitic infection. Infected patients remained about 33 days longer in hospital during their last admission than uninfected ones (P = 0.003). Schizophrenia started approximately 1 year earlier in infected men and about 3 years later in infected women, no such difference was observed in uninfected subjects.

Latent toxoplasmosis in schizophrenia may lead to more severe positive psychopathology and perhaps less favourable course of schizophrenia.