Toxocara eggs in public places worldwide - A systematic review and meta-analysis

Toxocariasis is a neglected tropical disease of humans. Although many studies have indicated or shown that environmental contamination with Toxocara species eggs is a major risk factor for toxocariasis in humans, there has been no comprehensive analysis of published data or information. Here, we conducted the first systematic review and meta-analysis of current literature to assess the global prevalence of Toxocara eggs in public places (including beaches, parks and playgrounds). We conducted searches of the PubMed, Embase, Scopus and Science Direct databases for relevant studies published until 20 April 2018, and assessed the prevalence rates of Toxocara eggs in public places. We used the random effects model to calculate pooled prevalence estimates, with 95% confidence intervals (CIs), and analysed data in relation to WHO geographical regions. Subgroup analysis and meta-regressions regarding the geographical and environmental variables were also performed. Of 2384 publications identified, 109 studies that tested 42,797 soil samples in 40 countries were included in the meta-analysis. The pooled global prevalence of Toxocara eggs in public places was 21% (95% CI, 16–27%; 13,895/42,797). The estimated prevalence rates in the different WHO regions ranged from 13% to 35%: Western Pacific (35%; 95% CI, 15–58%), Africa (27%; 95% CI, 11–47%), South America (25%; 95% CI, 13–33%), South-East Asia (21%; 95% CI, 3–49%), Middle East and North Africa (18%; 95% CI, 11–24%), Europe (18%; 95% CI, 14–22%), and North and Central Americas (13%; 95% CI, 8–23%). A high prevalence was significantly associated with high geographical longitude (P = 0.04), low latitude (P = 0.02) and high relative environmental humidity (P = 0.04). This meta-analysis of data from published records indicates that public places are often heavily contaminated with eggs of Toxocara. This finding calls for measures to reduce the potential risk of infection and disease in humans.