Global status of Toxoplasma gondii infection: systematic review and prevalence snapshots

Our group sought to determine the global status of T. gondii infection and to evaluate any continental and geographical trends by systematically examining the currently available epidemiological data on the prevalence of T. gondii infection. A comprehensive literature search was conducted from 10 electronic databases (Google Scholar, Science Direct, Embase, PubMed, PLOS ONE, Web of Knowledge, SciELO, MyAIS, Free Medical Journals, and Scopus) without date or language restrictions. Specific medical subject heading terms were used to search for human T. gondii seroprevalence studies that recruited subjects from general apparently healthy populations. The data were collated and analysed for both continental and global trends. The search identified 152 published studies that examined a total of 648,010 subjects. From these, 166,255 were seropositive for T. gondii infection indicating an average global seroprevalence rate of 25.7% (95% CI: 25.6 - 25.8%). The overall range of seroprevalence was determined to be 0.5 - 87.7%. African countries had the highest average seroprevalence rate of 61.4%, followed by Oceania with 38.5%, South America with 31.2%, Europe with 29.6%, USA/Canada with 17.5%, and Asia with 16.4%. Numerous environmental and human factors affect the differences in T. gondii seroprevalence rates observed between the various countries and continents. Monitoring the source and transmission may assist public health authorities to clarify the risk factors involved, as well as focus on implementing optimal state-specific health policies targeting T. gondii transmission control.