Although prenatal diagnosis and prenatal and neonatal therapy of congenital toxoplasmosis are available, there is controversy concerning the effectiveness of prophylaxis to prevent placental transmission. Experimental, parasitological, and clinical data suggest a “window of opportunity” following maternal infection. Among medications active against Toxoplasma gondii, mainly spiramycin (Spy) and pyrimethamine + sulfonamide combinations (P‐S) have been evaluated. Results from observational studies suffered treatment bias, since prescriptions differed according to the gestational age at seroconversion, which is the major risk factor for transmission, and many lacked precise timing. Some large retrospective studies found no difference in transmission according to prophylactic treatment, but transmission was lower when treatment started promptly after maternal seroconversion. A few recent studies adjusting for timing of infection observed lower transmission in case of P‐S than other or no prophylaxis. In the only randomized controlled trial, transmission was lower with P‐S than S (18.5% vs 30%, P = .147); this association was strengthened when the treatment was started within 3 weeks of seroconversion, and the incidence of fetal cerebral ultrasound signs was significantly reduced in the P‐S group. Rapid initiation of prophylactic therapy following maternal infection, which is usually asymptomatic, requires systematic screening for maternal seroconversion during pregnancy.

中文翻译：

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先天性弓形虫病：预防胎儿感染的化学预防的证据是什么？

尽管可以进行先天性弓形体病的产前诊断以及产前和新生儿治疗，但对于预防胎盘传播的预防措施的有效性存在争议。实验、寄生虫学和临床数据表明母体感染后有一个“机会之窗”。在对弓形虫有活性的药物中, 主要评估了螺旋霉素 (Spy) 和乙胺嘧啶 + 磺胺组合 (P-S)。观察性研究的结果存在治疗偏倚，因为处方因血清转化的胎龄而异，这是传播的主要危险因素，而且许多缺乏精确的时间安排。一些大型回顾性研究发现，根据预防性治疗，传播没有差异，但在母体血清转换后立即开始治疗时传播较低。最近的一些调整感染时间的研究观察到 P-S 情况下的传播率低于其他预防措施或没有预防措施。在唯一的随机对照试验中，P-S 的传播率低于 S（18.5% 对 30%，P= .147); 在血清转化后 3 周内开始治疗时，这种关联得到加强，P-S 组胎儿脑超声征象的发生率显着降低。母体感染后迅速启动预防性治疗，通常无症状，需要在妊娠期间系统筛查母体血清转换。