Monitoring of congenital toxoplasmosis has been in place in France since 2007. In this database, called TOXOSURV, monitoring is ensured by a network of laboratories.
Context of monitoring
Toxoplasmosis is a zoonosis caused by the protozoan parasite Toxoplasma gondii that is quite common in France as 50% of the population contracts it over its lifetime, and usually without any clinical symptoms. In women, infection during pregnancy can be due to congenital toxoplasmosis (or exceptionally in immunosuppressed pregnant women infected with it). The progression of congenital toxoplasmosis is variable, ranging from spontaneous abortion to generalized or severe neurological forms and even to infra-clinical forms (asymptomatic).
Even though toxoplasmosis is not an epidemic type infection, in France, congenital toxoplasmosis is considered to be a significant public health issue given the potentially severe clinical after effects (neurological or ophthalmological) in infected children, particularly in the absence of diagnosis and appropriate treatment. No monitoring system for congenital toxoplasmosis currently exists in France. Prevalence studies from the 1960s reported elevated sero-prevalence rates compared to other European countries. France established a significant national prevention programme for congenital toxoplasmosis back in 1978. The prevention programme was created without a complementary monitoring system for congenital toxoplasmosis, which is a major indicator in evaluating the effectiveness of the programme.
The National Reference Centre for Toxoplasmosis, in collaboration with the Institut de Veille Sanitaire (National Health Monitoring Institute), created a monitoring system based on the notification of cases of congenital toxoplasmosis. This monitoring system will help, for the first time, to systematically and continuously collect data on cases of congenital toxoplasmosis. This system could also help contribute to specifying and evaluating the national programme’s role in screening in France in the epidemiology of the infection.
Creating a monitoring system for congenital toxoplasmosis in France will help to:
- Estimate the incidence of congenital toxoplasmosis in France.
- Determine the number of cases of severe congenital toxoplasmosis at the time of diagnosis.
- Follow the tendencies of the disease (number of cases and their characteristics).
- Compare the incidences of the disease observed in France and other European countries.
Definition of cases of congenital Toxoplasmosis that must be reported:
Cases that are part of a surveillance programme from populations comprising:
- Live, developing foetuses
- Abortion remains (miscarriage or abortion/medical termination of pregnancy)
- Infants up to 12 months
in which the mother had a toxoplasma infection during her pregnancy or in the weeks preceding the pregnancy.
A case of congenital toxoplasmosis is defined as a subject:
- belonging to the target population
- for whom the infection was detected in France (including the overseas departments)
- for whom a toxoplasma infection was confirmed by at least one of the following criteria:
1. Detection of T. gondii in tissues (placenta, expulsion remains) or a biological fluid (amniotic fluid, CSF, blood from the umbilical cord or the new-born or ascites) through PCR, mouse inoculation or cell culture
NB: For detection in the placenta, the confirmation of the diagnosis must absolutely be backed up by another biological criterion (parasitological or immunological)
2. Specific immune response to toxoplasmosis:
- presence of specific IgM or IgA antibodies during the first week of life
- or presence of neosynthesized IgG or IgM or IgA antibodies
- or an increase in specific IgG antibodies in successive samples taken after the first month of life
- or persistence of specific IgG antibodies at the age of 12 months