Toxocara infection/exposure and the risk of schizophrenia: a systematic review and meta-analysis

Toxocariasis is an important neglected disease that could have a role in the development of some neurological disorders, such as schizophrenia (SCZ). We performed the first systematic review and meta-analysis on observational studies to evaluate the possible association between Toxocara infection/exposure and SCZ. Systematic searching (PubMed, Scopus, Web of Science and Google Scholar) was performed, up to 15 August 2020, to identify the relevant studies. We used a random effects meta-analysis model to generate the pooled OR and 95% CIs. The research process resulted in the identification of six studies related to the subject of interest entailing 411 SCZ patients and 2047 controls. Our results demonstrated that the SCZ patients (15%; 95% CI 6.8 to 29.9%) had higher pooled seroprevalence of Toxocara infection/exposure than the control group (3.3%; 95% CI 1.1 to 9.4%), showing a significant association (pooled OR, 4.06; 95% CI 1.14 to 14.43). Our findings suggested that Toxocara infection/exposure might have an important but neglected contribution to SCZ development. However, further well-designed and large-scale observational studies are needed to illuminate this association. Because many other environmental and genetic factors may be strong confounders, more mechanistic/experimental studies in animal models are also necessary to further define the mechanism of this association.