Frequency of exposure to Toxoplasma gondii in COVID-19 patients: a systematic review and meta-analysis

Background: Toxoplasmosis is a chronic protozoan parasitic infection that affects nearly one-third of the global population. During the COVID-19 pandemic, cases were observed in patients with COVID-19 and toxoplasmosis. Therefore, this systematic review and meta-analysis aimed to determine the frequency of Toxoplasma gondii exposure in patients with COVID-19. Methods: A literature search was conducted in six databases or search tools (PubMed, Scopus, Embase, Web of Science, ScienceDirect, and Google Scholar) until March 3, 2024. Study selection, quality assessment, and data extraction were performed independently by three investigators. Statistical analysis was performed using R version 4.3, applying a random-effects model. The quality of the included observational studies was assessed using the “JBI-MAStARI”. Results: A total of 5,936 studies were retrieved, 13 of which were included in the final meta-analysis. The sample included a total of 2,947 patients with COVID-19 from four countries, of whom approximately 43.3% were men and 49.4% were women. Among the patients, 1,323 showed evidence of exposure to T. gondii through IgG detection, while 1,302 COVID-19 patients were explicitly examined for T. gondii by IgM detection, and 36 positive cases were identified. The frequency of exposure to T. gondii, determined by the presence of IgG in patients with COVID-19, reached 49% (95% CI: 34–63%; 2,947 participants; 13 studies; I² = 98%, p < 0.01). In addition, the frequency of exposure to T. gondii, evaluated by IgM presence in patients with COVID-19, was 2% (95% CI: 0–6%; 1,302 participants; 6 studies; I² = 94%, p < 0.01). Conclusion: It was shown that almost half of COVID-19 patients had previous exposure to T. gondii through the presence of IgG, and a small percentage, 2%, showed active infection through IgM detection. Although the results indicate a possible correlation between exposure to T. gondii and the presence of COVID-19, it is essential to note that this study is based on observational research, which precludes establishing a causal relationship. Consequently, further research is required to deepen understanding of the interaction between the two conditions. Terms used: The Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI), Prospective International Registry of Systematic Reviews (PROSPERO), and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).