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.