Ecological comparison of the risks of mother-to-child transmission and clinical manifestations of congenital toxoplasmosis according to prenatal treatment protocol

Abstract

We compared the relative risks of mother-to-child transmission of Toxoplasma gondii and clinical manifestations due to congenital toxoplasmosis associated with intensive prenatal treatment in Lyon and Austria, short term treatment in 51% of Dutch women, and no treatment in Danish women. For each cohort, relative risks were standardized for gestation at seroconversion. In total, 856 mother-child pairs were studied: 549 in Lyon, 133 in Austria, 123 in Denmark and 51 in The Netherlands. The relative risk for mother-to-child transmission compared to Lyon was 1.24 (95% CI: 0.88, 1.59) in Austria; 0.59 (0.41, 0.81) in Denmark; and 0.65 (0.37, 1.01) in The Netherlands. Relative risks for clinical manifestations compared with Lyon (adjusted for follow-up to age 3 years) were: Austria 0.19 (0.04, 0.51); Denmark 0.60 (0.13, 1.08); and The Netherlands 1.46 (0.51, 2.72). There was no clear evidence that the risk of transmission or of clinical manifestations was lowest in centres with the most intensive prenatal treatment.

Clinical practice guideline. Integral Care Guidelines for the prevention, early detection and treatment of pregnancy, childbirth and puerperium complications: Section on toxoplasmosis in pregnancy

“…The analysis and direct comparison of the results of the European screening programs were not able to conclude which is the best strategy, given the geographic heterogeneity for the risk of infection 42 . Clustered data from systematic reviews of observational cohorts across continents shows that the benefit of prenatal treatment to reduce transmission is only obtained if treated prior to seroconversion week 4; After this period of infection, there is uncertainty as to whether there is any benefit to the treatment.…”

Effectiveness of Prenatal Treatment for Congenital Toxoplasmosis: A Meta-analysis of Individual Patients’ Data

“…Studies of prenatal screening varied from a monthly to three-monthly re-testing schedule for susceptible mothers ( Table 1). Details of the prenatal treatment regimens are published elsewhere 4,7,12,13,15 . The crude risk of mother to child transmission shown in Table 1 varies between cohorts due mainly to differences in gestational age at maternal seroconversion.…”

“…There is no consensus about the most effective screening strategy or the best type of treatment. Uncertainty about the benefits of prenatal treatment 9 and concerns about adverse treatment effects and the infrastructure and costs required to implement prenatal screening have led to diverse policies including no screening, neonatal screening 6,10,11 and prenatal screening with monthly or 3-monthly re-testing schedules 4,8,12,13 . In those countries where prenatal screening applies, recommendations for treatment may differ.…”

“…However, new observational data have been published since then: three analyses of retrospective cohort studies 12,13,15,16 and the results of a large prospective, multicentre cohort study 4,7 . None of these studies reported a significant effect of treatment on mother to child transmission but none could exclude clinically important effects.…”

“…None of these studies reported a significant effect of treatment on mother to child transmission but none could exclude clinically important effects. The findings for the effect of prenatal treatment on the risk of clinical manifestations of congenital toxoplasmosis (intracranial and ocular lesions) have been inconsistent 7,12,13,16 .…”