High prevalence of congenital toxoplasmosis in Brazil estimated in a 3-year prospective neonatal screening study

Background A pilot neonatal screening programme revealed a high (approximat ely 1 per 4800 live births) prevalence of congenital toxoplasmosis (CT) in the State of Rio Grande do Sul, Brazil. The purpose of this paper was to es timate in a larger prospective study the prevalence of CT in the country. Methods At the beginning of the study, an in-house indirect enzyme immunoas say (ELA) was used, to be later replaced with a commercial capture IgM fluo rometric enzyme immunoassay (FEIA). Both methods detect specific anti-Toxop lasma gondii IgM-class antibodies eluted from dried blood spots. Results Of the total of 140 914 samples received from all over the country, 47 cases were identified and confirmed as CT. This finding suggests a prev alence of 1 per 3000 live births. Of the 47 patients, only eight (17%) had clinical manifestations: two had intracranial calcifications, four had reti nal scars, one had an intracranial calcification and retinal scars, and one had hepatosplenomegaly with lymphoadenopathy. The testing was paid for by the patients' families who volunteered for the study and gave their informe d consent. Conclusion The 3-year prospective study using sensitive detection methods, reliable confirmation, and feedback from clinicians showed that CT has an e xtraordinarily high prevalence in Brazil, in fact the highest ever reported in the world. Although the long-term efficacy of treatment of CT has not b een well documented, in view of the availability of reliable diagnostics, c onfirmation and monitoring, functional logistics, and networking for screen ing, the insidious nature of the sequelae and the very high prevalence of t he disease, neonatal screening for CT should be considered an alternative t o no screening at all.