Dépistage de la toxoplasmose materno-foetale : étude des cas suivis à l’Institut Pasteur de Tunis (2007–2010)

Abstract

Toxoplasmosis when occurring during pregnancy can be transmitted to the fetus and lead to congenital toxoplasmosis (CT). Therefore, pregnant women are a risk group, for which it is necessary to determine the serologic profile. The objective of this study is to determine the serologic profile of toxoplasmosis in pregnant women followed at the Parasitology Laboratory of the Pasteur Institute in Tunis, to establish the prevalence of toxoplasmic infections during pregnancy and the incidence of the CT, noting the difficulties faced in the interpretation of serological results. This is a retrospective study concerning 2833 toxoplasmic serologies practiced on 2070 pregnant women, followed at the Parasitology-Mycology Laboratory of the Pasteur Institute of Tunis, between 2007 and 2010. Serological diagnosis of toxoplasmosis was done by ELISA (Enzyme Linked Immunosorbent Assay) for the detection of Immunoglobulin (Ig) G and M and the study of toxoplasmosis IgG avidity. Prenatal diagnosis was performed for 58 women by amniotic fluid sampling. Toxoplasma gondii was detected by Polymerase Chain Reaction (PCR). At birth, the diagnosis of congenital toxoplasmosis was established based on serology. The toxoplasmic serologies carried out have shown that 45.6% of the pregnant women were formerly immunized while 49.6% had a negative serology. A toxoplasmosis primary infection acquired during pregnancy was detected in 79 cases (3.8%). Among them, 33% had a true seroconversion while 67% had a recent toxoplasmosis infection in view of the positivity of IgG and IgM on the first sample with a low index of avidity (IA). For 21 parturients whose serology showed the presence of IgG, IgM and an intermediate or high IA. Among the 58 parturients in whom prenatal diagnosis was performed, PCR was positive in four cases. After birth, six cases of congenital toxoplasmosis were detected by serology.