Little is known about the best way to prevent congenital toxoplasmosis
. Until recently, the major effort was directed at preventing the dise
ase during pregnancy by the application of hygienic measures (primary
prevention). With the advent of detecting congenital toxoplasmosis ant
enatally, another method for reducing the incidence of congenital toxo
plasmosis becomes possible (secondary prevention). In this study, we e
valuate these two methods for the prevention of congenital toxoplasmos
is. For 12 consecutive years, we studied the incidence of congenital t
oxoplasmosis in 11,286 consecutive pregnant women. The impact of prima
ry prevention was studied by measuring the reduction in seroconversion
when hygienic measures were systematically applied. Primary preventio
n reduces the seroconversion rate during pregnancy by 63% (P = 0.013).
The effect of secondary prevention was studied in 76 pregnant women a
t risk of delivering a child with congenital toxoplasmosis. Secondary
prevention by means of serological screening combined with prenatal di
agnosis detected congenital toxoplasmosis correctly in eight infected
fetuses. Secondary prevention reduced the incidence of congenital toxo
plasmosis an additional 40%. This reduction would predominantly be see
n 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 or congenital toxopl
asmosis. Whether or not screening for toxoplasmosis during pregnancy s
hould be combined with primary prevention depends on the importance of
congenital toxoplasmosis as a health problem in a given geographic ar
ea.