Toxoplasma oocysts in the soil of public places worldwide: a systematic review and meta-analysis

Toxoplasmosis is a zoonotic and cosmopolitan infection. Although a few studies have evaluated the prevalence of Toxoplasma oocysts in the soil of public places, the present study was conducted to provide insights into environmental contamination levels and its potential transmission to humans on a global scale. A systematic search was conducted using bibliographic databases through 30 August 2020. A random effects model was utilized to estimate pooled prevalence with 95% confidence intervals (CIs). Subgroup analysis and meta-regressions were also performed on the geographical and environmental parameters. Finally, 22 articles, wherein 15 420 soil samples were examined, met the systematic review and meta-analysis requirements. The mean pooled prevalence of Toxoplasma oocysts was estimated at 16% (95% CI 10 to 26) in public places. The estimated prevalences in Europe, South America, Asia and North America were 23% (95% CI 4 to 65), 22% (95% CI 18 to 26), 15% (95% CI 0.06 to 33) and 8% (95% CI 0.00 to 97), respectively. An increasing trend was observed in the prevalence of Toxoplasma oocysts with increasing latitude (41-56°), decreasing longitude (0-40°) and increasing relative humidity (≥76%). Loop-mediated isothermal amplification and polymerase chain reaction methods revealed the highest and lowest prevalence rates, respectively, in the detection of Toxoplasma oocysts. Awareness of the health authorities and people about Toxoplasma prevalence in the soil of public places and its risk factors is of great importance to developing effective strategies to prevent infection.