Acute Toxoplasma infection in pregnant women worldwide: A systematic review and meta-analysis

Background: Acute Toxoplasma infection (ATI) during pregnancy, if left untreated, can cause severe adverse outcomes for the fetus and newborn. Here, we undertook a meta-analysis to estimate the worldwide prevalence of ATI in pregnant women. Methods: We searched international databases for studies published between January 1988 and November 2018. We included population-based cross-sectional and prospective cohort studies that reported the prevalence of ATI in pregnant women. Data were synthesized using a random effect model to calculate the overall prevalence of ATI (with a 95% CI) in six WHO regions and globally. We also performed linear meta-regression analyses to investigate associations of maternal, socio-demographic, geographical and climate parameters with the prevalence of ATI. Results: In total, 217 studies comprising 902,228 pregnant women across 74 countries were included in the meta-analysis. The overall prevalence of ATI in pregnant women globally was 1.1% (95% CI: 0.9–1.2%). In studies where more strict criteria for ATI were used, the overall prevalence was 0.6% (95% CI: 0.4–0.7%). The prevalence was highest in the Eastern Mediterranean region (2.5%; 95%CI: 1.7–3.4%) and lowest in the European region (0.5%; 95% CI: 0.4–0.7%). A significantly higher prevalence of ATI was found in countries with lower income levels (P = 0.027), lower human development indices (P = 0.04), higher temperatures (P = 0.02) and lower latitudes (P = 0.005) and longitudes (P = 0.02). Conclusions: The risk of acquiring ATI during gestation is clinically important and preventive measures to avoid exposure of pregnant women to Toxoplasma infection should be strictly applied. Author summary: Acute infection during pregnancy with the protozoan parasite Toxoplasma gondii, if left undiagnosed and untreated, is linked to a wide range of medical complications, and severe adverse outcomes for the infected fetus and newborn. This is the first comprehensive systematic review and meta-analysis of the global prevalence of ATI in pregnant women, and was based on 217 studies of a total of 902,228 pregnant women from 74 countries. The overall global prevalence of ATI was 1.1%. According to studies that used strict criteria (seroconversion and low IgG avidity) for the definition of ATI, 0.6% of pregnant women had ATI during gestation. Countries with high-income levels and higher human development indices had significantly lower prevalence of ATI. In addition, the prevalence of ATI varied among countries depending on geographical location and climatic features. The findings of this study should increase awareness among public health leaders and educators regarding the global burden of ATI in pregnant women—which translates to a significant number of children worldwide being at risk of acquiring congenital toxoplasmosis and developing long-term sequelae—if maternal infection is left undiagnosed and untreated. The findings also indicate a need for universal prenatal screening for early diagnosis and treatment.