[Prevention of congenital toxoplasmosis in France. Risk assessment. Results and perspectives of prenatal screening and newborn follow up].

In France, a national program for the prevention of congenital toxoplasmosis has been set up 25 years ago. This program is here presented and discussed in details. It is based on a decision tree well defined, with pre and/or per gravidic serological screening with several different tests, completed, if necessary, by ultrasounds examinations of the fetus, biomolecular tests (PCR) on amniotic fluid, and by clinical, biological, and radiological surveillance of neo-nates. The purpose of this prevention program is to: 1/identify nonimmune young women and limit their contamination risk during pregnancy by appropriate counseling on hygiene and diet; 2/screen and treat per gravidic toxoplasmosis as early as possible so as to prevent or limit transmission to the fetus and its consequences. 3/in utero diagnose and treat infestation of the fetus; 4/diagnose and treat asymptomatic congenital toxoplasmosis in neonates, to prevent risks of reactivation and late complications, especially ocular. Such a prevention program has a cost validated by the prevalence of acquired toxoplasmosis in adults in France (over 50% of the population) and by the yearly incidence of congenital toxoplasmosis (at least 0.1% of births according to the best hypothesis). These 6 to 700 congenital toxoplasmosis cases per year may be compared to the 6 to 7,000 per gravidic seroconversions which could lead to fetal contamination if no preventive measures are taken. Nevertheless, as it is often the case in the field of prevention, it is very difficult to statistically assess the efficacy of this program even though several arguments show that it allows to eliminate the most serious toxoplasmosis, sources of serious handicaps at birth, and to limit the frequency of late complications (especially retino-choroiditis) of asymptomatic infections in neonates. The position of European countries varies as to prevention of congenital toxoplasmosis. Some countries (Austria, Belgium) have national prevention programs similar to the French one, whereas others have set up only limited programs or set up no systematic prevention. These differences may be accounted for by the different frequencies of toxoplasmic risk. It seems mandatory to forget all dogmatism and not to stick to a strictly statistical approach for a disease with not only medical but also social and human consequences.