Sulfadiazine and pyrimethamine in the postnatal treatment of congenital toxoplasmosis: what are the options?

Pre- and neonatal screening for congenital toxoplasmosis rests upon the assumption that treatment is beneficial on either acute symptoms or in preventing later reactivation. Postpartum treatment of congenital toxoplasmosis with sulfadiazine and pyrimethamine has remained almost unchanged for 50 years. More recently, sulfadiazine has been substituted by sulfadoxine, which has a much longer half-life and provides a basis for a dose schedule with higher compliance. Newer drugs with potential effects against Toxoplasma gondii, such as azithromycin, atovaquone and clindamycin, require further evaluation in animal models and human studies. No randomized controlled trials have ever been conducted. The available studies are either observational studies of groups of referred patients or observational studies with historical controls accrued over many years, often decades. Pre- and neonatal screening for congenital toxoplasmosis is performed on more than two million pregnant women every year in Europe, North and South America at the estimated cost of more than 500 million annually. The benefit needs to be documented by a prospective, placebo-controlled randomized study, which needs to be organized and financed by the countries performing nationwide, universal screening programs.