Centre for Parasitology and Disease Research, School of Environment and Life Sciences, University of Salford, Salford, M5 4WT, UK.
Parasitology. 2009 Dec;136(14):1877-85. doi: 10.1017/S0031182009990941. Epub 2009 Sep 21.
Toxoplasma gondii is a highly ubiquitous and prevalent parasite. Despite the cat being the only definitive host, it is found in almost all geographical areas and warm blooded animals. Three routes of transmission are recognised: ingestion of oocysts shed by the cat, carnivory and congenital transmission. In natural populations, it is difficult to establish the relative importance of these routes. This paper reviews recent work in our laboratory which suggests that congenital transmission may be much more important than previously thought. Using PCR detection of the parasite, studies in sheep show that congenital transmission may occur in as many as 66% of pregnancies. Furthermore, in families of sheep on the same farm, exposed to the same sources of oocysts, significant divergent prevalences of Toxoplasma infection and abortion are found between different families. The data suggest that breeding from infected ewes increases the risk of subsequent abortion and infection in lambs. Congenital transmission rates in a natural population of mice were found to be 75%. Interestingly, congenital transmission rates in humans were measured at 19.8%. The results presented in these studies differ from those of other published studies and suggest that vertical transmission may be much more important than previously thought.
刚地弓形虫是一种高度普遍存在的寄生虫。尽管猫是唯一的终宿主，但它几乎存在于所有地理区域和温血动物中。有三种公认的传播途径：摄入猫排出的卵囊、肉食和先天性传播。在自然种群中，很难确定这些途径的相对重要性。本文综述了我们实验室的最新研究工作，这些工作表明先天性传播可能比以前认为的更为重要。使用寄生虫的 PCR 检测，对绵羊的研究表明，先天性传播在多达 66%的妊娠中可能发生。此外，在同一农场的绵羊家庭中，暴露于相同的卵囊来源，不同家庭之间发现了弓形虫感染和流产的显著不同流行率。这些数据表明，从感染的母羊繁殖会增加随后流产和羔羊感染的风险。在自然小鼠种群中发现先天性传播率为 75%。有趣的是，人类的先天性传播率为 19.8%。这些研究的结果与其他已发表的研究不同，表明垂直传播可能比以前认为的更为重要。
