Meta-analysis of the Relationship Between Toxoplasma Gondii and Schizophrenia

Toxoplasma gondii (T. gondii), which is an obligate intracellular protozoan parasite, could infect a wide range of hosts including humans. It infects approximately one-third of the entire human population. Infection with T. gondii can lead similar psychotic symptoms of schizophrenia. Starting from this information, numerous studies have revealed that maternal, acute and chronic T. gondii infections predispose to schizophrenia. The aim of this work was to evaluate the relationship between T. gondii and schizophrenia with a meta-analysis study using current data. 112 studies were reached using PubMed, Google Scholar and Council of Higher Education (YÖ̈K) Thesis Center databases. 15 studies which included a proportion of seropositive schizophrenia patients and controls were further examined in a meta-analysis. Among these studies, 13 of them showed a positive association between higher anti-T. gondii IgG level and patients with schizophrenia in the experimental groups whereas the remaining 2 studies showed a negative correlation. According to the random effects model, it was seen lower limit of 0.180 and upper limit of 0.490 with a standard error of 0.279 and a 95% confidence interval. The average effect size value was calculated as 0.335. This result having positive average effect size indicated that there was a positive association between T. gondii infection with a higher IgG level and the presence of schizophrenia.