Congenital toxoplasmosis in Martinique: Clinical features and Caribbean genotypes in a comparative study with mainland France

• Martinican isolates of congenital toxoplasmosis belong to Caribbean lineages. • A higher rate of transmission was observed than in mainland France. • These isolates do not seem to cause more severe congenital toxoplasmosis than Type II isolates. • The rate of ocular lesions is 21% within the first two years of life. • Parasite genotypes may play a role in the epidemiology of congenital toxoplasmosis. • It is important to monitor affected children. To assess the epidemiology, clinical features, and genotypic characteristics of congenital toxoplasmosis (CT) in Martinique over a 12-year period. We conducted a retrospective study of CT cases diagnosed at the University Hospital of Martinique between 2010 and 2022. We then compared the clinical, genotypic, and epidemiological data of these cases with those from the Limousin region in mainland France. Twenty-five CT cases were identified in Martinique, with no pregnancy terminations or in utero deaths. Clinical findings showed low severity at birth, with ocular involvement of 8% within the first few months and 21% within the first two years. Of the 11 isolates genotyped in Martinique, nine belonged to Caribbean lineages (Caribbean 1, 2, and 3), whereas all the isolates from Limousin were of the Type II lineage. There was no significant difference in clinical severity between the two regions. However, the incidence of CT was three times higher in Martinique than in mainland France. Although the genetic diversity of Toxoplasma gondii strains associated with diagnosed cases of CT in Martinique differed from that observed in mainland France, no increase in clinical severity was observed; however, a higher risk of transplacental passage was possible. These findings provide important data to improve our understanding of the epidemiological and clinical aspects of CT in relation to the genetic diversity of circulating strains in Martinique. Furthermore, they emphasize the importance of screening for CT on an ongoing basis and monitoring affected children.