Geo-climatic factors and prevalence of chronic toxoplasmosis in pregnant women: A meta-analysis and meta-regression

In this study, we evaluated the effects of geo-climatic parameters and other potential risk factors on the prevalence of chronic toxoplasmosis (CT) in pregnant women. We searched PubMed/MEDLINE, Web of Science, EMBASE, Scopus, and SciELO databases for seroepidemiological studies published between January 1988, and February 2021. We performed meta-analysis and meta-regression by using a random effect model to synthesize data. A total of 360 eligible datasets, including 1,289,605 pregnant women from 94 countries, were included in this study. The highest and lowest prevalence rates were estimated for latitudes of 0-10° (49.4%) and ≥50° (26.8%); and for the longitude of 80-90° (44.2%) and 110-120° (7.8%), respectively. Concerning climatic parameters, the highest and lowest prevalence rates were estimated in regions with the mean relative humidities of >80% (46.6%) and <40% (27.0); annual precipitation between 1000 and 1500 mm (39.2%) and 250-500 mm (26.8%); and mean annual temperature of 20-30 °C (36.5%), and <7 °C (24.9%), respectively. Meta-regression analyses indicated significant increasing trends in prevalence of CT in pregnant women with decrease in geographical latitude (coefficient, = -0.0035), and geographical longitudes (C = -0.0017). While it was positively associated (P < 0.01) with the mean environmental temperature (C = 0.0047), annual precipitation (C = 0.000064), and mean relative humidity (C = 0.002). Our results highlighted various effects of environmental parameters on the prevalence of CT. Therefore, different regions in the world may benefit from different types of interventions, and thus, novel preventive measures in a region should be developed according to local climate, agricultural activities and people culture.

Toxoplasma gondii infection and risk of Parkinson and Alzheimer diseases: A systematic review and meta-analysis on observational studies

In the past decade, Toxoplasma gondii infection has been recognized as a potential risk for many psychiatric and neurological disorders. We performed this systematic review and meta-analysis to evaluate the association between Toxoplasma infection and Parkinson's and Alzheimer's diseases. PubMed, Web of science, Scopus and Embase databases were searched up to September 30, 2018 for studies that reported risk of Parkinson's and Alzheimer's diseases associated with Toxoplasma infection. We used a random effects meta-analysis model to generate the pooled odds ratio (OR) with 95% confidence intervals (CIs). Eleven studies, including seven studies for Parkinson's disease (428 patients and 540 controls) and four studies for Alzheimer's disease (301 patients and 313 controls), were included in the meta-analysis. We found that there was no statistically significant association between Toxoplasma infection, as determined by IgG serology, IgM serology, and PCR with increased risk of Parkinson's disease (OR, 1.14; 95% CI, 0.78-1.68), (OR, 1.61; 95% CI, 0.33-7.76) and (OR, 1.87; 95% CI, 0.43-8.05), respectively. The OR for association of Toxoplasma infection, based on IgG serology with Alzheimer's patients, compared to control group, was (OR, 1.38; 95% CI, 0.99-1.92), demonstrating a marginally significant association between Toxoplasma infection and Alzheimer's disease. Our findings do not support a general hypotheses regarding an associative relationship between Toxoplasma infection and Parkinson's disease, but do support a marginally significant association between Toxoplasma infection and Alzheimer's disease; this association should be investigated further through longitudinal and experimental studies.