Evaluation of the possibilities for preventing congenital toxoplasmosis.

Little is known about the best way to prevent congenital toxoplasmosis. Until recently, the major effort was directed at preventing the disease during pregnancy by the application of hygienic measures (primary prevention). With the advent of detecting congenital toxoplasmosis antenatally, another method for reducing the incidence of congenital toxoplasmosis becomes possible (secondary prevention). In this study, we evaluate these two methods for the prevention of congenital toxoplasmosis. For 12 consecutive years, we studied the incidence of congenital toxoplasmosis in 11,286 consecutive pregnant women. The impact of primary prevention was studied by measuring the reduction in seroconversion when hygienic measures were systematically applied. Primary prevention reduces the seroconversion rate during pregnancy by 63% (P = 0.013). The effect of secondary prevention was studied in 76 pregnant women at risk of delivering a child with congenital toxoplasmosis. Secondary prevention by means of serological screening combined with prenatal diagnosis detected congenital toxoplasmosis correctly in eight infected fetuses. Secondary prevention reduced the incidence of congenital toxoplasmosis an additional 40%. This reduction would predominantly be seen in the group of mildly to severely affected fetuses. From this study, the effectiveness of primary prevention is obvious. Health education on how to avoid toxoplasmosis during pregnancy should become standard obstetric care. Adequate serological screening and prenatal diagnosis can be helpful in reducing further the incidence of congenital toxoplasmosis. Whether or not screening for toxoplasmosis during pregnancy should be combined with primary prevention depends on the importance of congenital toxoplasmosis as a health problem in a given geographic area.