Toxoplasmosis is considered as the most prevalent parasitic zoonotic infection worldwide. The parasitic cycle is mostly known, but the relative contribution of different sources and pathways of transmission was not previously studied by a meta-analysis. A systematic review and a meta-analysis of case-control, cohort, and cross-sectional studies were performed to determine the main risk factors associated with sporadic Toxoplasma infection. Suitable scientific articles were identified through a systematic literature search and subjected to a methodological quality assessment. Mixed-effects meta-analysis models were adjusted by population type – children, mixed population, and pregnant women – to appropriate data partitions. 187 primary studies passed the quality assessment stage, investigating risk factors for sporadic infection with Toxoplasma gondii conducted between 1983 and 2016. Cases were defined by serology.

The meta-analysis of Toxoplasma sporadic infections revealed the significance of transmission by environmental factors such as contact with soil and contact with animals, in particular cats. The consumption of raw or undercooked meat and unwashed vegetables significantly increased the odds of acquiring the disease. Shellfish and raw milk were identified as significant sources of toxoplasmosis. Almost all meat categories were identified as risk factors: pork, poultry, beef, processed meat, lamb, and game meat. Contaminated drinking water may play a role in the acquisition of infection. Moreover, the lack of hygiene in preparing food was identified as a risk factor. A significant risk factor for pregnant women is traveling abroad. Lastly, blood transfusion (in pregnant women) and immunocompromised conditions were found associated with positive serology. The broad definition of exposures and the use of serology for the case definition are the main limitations for the interpretation of the results of this meta-analysis. The transmission pathways require further investigations using longitudinal studies and subtyping approaches.

弓形虫病被认为是全世界最普遍的寄生虫人畜共患病感染。寄生周期最广为人知，但是以前没有通过荟萃分析研究不同来源和传播途径的相对贡献。进行了病例对照，队列研究和横断面研究的系统评价和荟萃分析，以确定与散发性弓形虫相关的主要危险因素。感染。通过系统的文献检索确定合适的科学文章，并进行方法学质量评估。根据人群类型（儿童，混合人群和孕妇）调整了混合效应荟萃分析模型，以适应适当的数据分区。1983年至2016年进行的187项基础研究通过了质量评估阶段，调查了弓形虫散发感染的危险因素。病例按血清学确定。

弓形虫的荟萃分析零星的感染揭示了环境因素传播的重要性，这些环境因素包括与土壤的接触以及与动物（尤其是猫）的接触。食用生的或未煮熟的肉和未洗的蔬菜会大大增加患病的几率。贝类和原料奶被认为是弓形虫病的重要来源。几乎所有肉类都被确定为危险因素：猪肉，禽肉，牛肉，加工肉，羊肉和野味。被污染的饮用水可能在感染的获得中起作用。此外，人们还认为准备食物时缺乏卫生是危险因素。孕妇的重要危险因素是出国旅行。最后，发现输血（孕妇）和免疫功能低下的疾病与血清学阳性有关。暴露的广泛定义以及病例定义中血清学的使用是该荟萃分析结果解释的主要限制。传播途径需要使用纵向研究和亚型分析方法进行进一步研究。