Prenatal treatment of congenital toxoplasmosis with antibiotics might substantially reduce the proportion of infected fetuses that develop serious neurological sequelae (brain damage, epilepsy, deafness, blindness, or developmental problems) or die, and could be particularly effective in fetuses whose mothers acquired Toxoplasma gondii, the parasite that causes toxoplasmosis, during the first third of pregnancy. These are the findings of an observational study by Ruth Gilbert from the UCL Institute of Child Health, London, UK, and colleagues and published in this week's PLoS Medicine.
Toxoplasmosis is a very common parasitic infection but most infected people never know they have the disease. However, about a quarter of women who are infected with toxoplasmosis during pregnancy transmit the parasite to their fetus. The authors followed 293 children in six European countries in whom congenital toxoplasmosis had been identified by prenatal screening (France, Austria, and Italy) or by neonatal screening (in Denmark, Sweden, and Poland). Two-thirds of the children received prenatal treatment for toxoplasmosis with the antibiotics spiramycin or pyrimethamine-sulfonamide.
23 (8% of the fetuses) developed serious neurological sequelae or died, nine of which were terminated during pregnancy. By comparing the number of children who had serious neurological sequelae who received prenatal treatment with the number among children who did not receive prenatal treatment, the authors estimated that prenatal treatment of congenital toxoplasmosis reduced the risk of serious neurological sequelae by three-quarters. Furthermore, they found that to prevent one case of serious neurological sequelae after maternal infection at 10 weeks of pregnancy, it would be necessary to treat three fetuses with confirmed infection and to prevent one case of SNSD after maternal infection at 30 weeks of pregnancy, 18 infected fetuses would need to be treated. The authors also found that that the effectiveness of the antibiotics used, pyrimethamine-sulfonamide and the less toxic spiramycin, was similar.
The authors explain how these results should be interpreted. They conclude: "The finding that prenatal treatment reduced the risk of [serious neurological sequelae] in infected fetuses should be interpreted with caution because of the low number of [serious neurological sequelae] cases and uncertainty about the timing of maternal seroconversion." The authors add: "As these are observational data, policy decisions about screening require further evidence from a randomized trial of prenatal screening and from cost-effectiveness analyses that take into account the incidence and prevalence of maternal infection."
Funding: The research was part of the European multicentre study on congenital toxoplasmosis, funded by the European Commission (BIOMED II No. BMH4-CT98-3927 and QLG5-CT-2000-00846). Additional support was provided by the National Eye Institute, grant code R03 EY015287-01. Research at the Institute of Child Health and Great Ormond Street Hospital for Children NHS Trust benefits from R&D funding received from the NHS Executive. The funding sources had no role in the study design; in the collection, analysis, and interpretation of data; or in the decision to submit the paper for publication. All authors declare they have no financial disclosures relating to the manuscript to declare.
Competing Interests: The authors have declared that no competing interests exist.
Citation: Cortina-Borja M, Tan HK, Wallon M, Paul M, Prusa A, et al. (2010) Prenatal Treatment for Serious Neurological Sequelae of Congenital Toxoplasmosis: An Observational Prospective Cohort Study. PLoS Med 7(10): e1000351. doi:10.1371/journal.pmed.1000351
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