An Updated Systematic Review and Meta-Analysis of the Prevalence of Toxocara spp. Eggs in the Soil of Public Areas in Iran

Human toxocariasis (HT), caused by the larvae of Toxocara canis and Toxocara cati, is a globally prevalent parasitic disease with significant public health implications. Although soil is a primary route for the transmission of Toxocara spp., data on soil contamination in Iran remain limited. To address this gap, the present study expands upon a systematic review published in ۲۰۱۸, which analyzed studies conducted between January ۲۰۰۰ and November ۲۰۱۶. Using recent data to guide control strategies, the study provides an updated estimate of the prevalence of Toxocara spp. eggs in the soil of public areas in Iran. Accordingly, a comprehensive literature review was performed in accordance with PRISMA guidelines, covering studies published between January ۲۰۰۰ and April ۲۰۲۵. A random-effects meta-analysis was performed to pool prevalence rates. In addition, associations with geographic and environmental factors were examined through meta-regression and sensitivity analyses. Overall, ۲۸ studies (۳۱ datasets) were included, comprising ۶,۲۶۴ soil samples collected from ۲۵ provinces of Iran. The pooled prevalence of Toxocara spp. eggs was ۱۶% (۹۵% confidence interval: ۱۲–۲۱%), with high heterogeneity (I²= ۹۴.۴%, P< ۰.۰۰۱). This high heterogeneity across studies may be attributed to differences in sampling methods, climatic conditions, study quality, and regional variations in stray animal density. The prevalence of this species varied by region and climate, with the highest rates reported in the central region (۲۳%) and in hot desert climates (۲۰%). The sample size, year of publication, or environmental variables had no statistically significant effects. These findings underscore significant environmental contamination by Toxocara spp. eggs throughout Iran. Further, this contamination indicates an ongoing risk of human infection. In general, the results highlight the need for geographically targeted interventions, public education, and integrated One Health strategies to inform health policies and prevent HT.