Prevention of toxoplasmosis during pregnancy--an epidemiologic survey over 22 consecutive years.

BACKGROUND: Prevention of congenital toxoplasmosis is most often based on the
results of a serological screening program in pregnant women followed by prenatal
and postnatal treatment of women and their newborns when infection is already
established during pregnancy or on cord blood (secondary prevention). Little
effort has been made to study primary prevention of toxoplasmosis during
pregnancy. OBJECTIVE: To assess the possibilities of two different programs aimed
at preventing the acquisition of toxoplasmosis during pregnancy. METHODS: During
the first study period (1979-1982) the natural incidence of toxoplasmosis in
pregnancy was studied in 2986 pregnant women. In the second study period
(1983-1990) the incidence of toxoplasmosis was studied in 8300 women. During this
period, seronegative women received a written list of recommendations on how to
avoid a toxoplasma infection during pregnancy. In the third study period
(1991-2001) the incidence of toxoplasmosis was studied in 16,541 women. During
this period, the prevention campaign consisted of a leaflet explaining a)
toxoplasmosis as a disease and b) what measures should be taken to avoid
toxoplasmosis during pregnancy. The third part of the campaign involved a
reiteration of these recommendations during antenatal classes held around
mid-gestation. The impact of the two prevention programs was studied by measuring
the seroconversion rate in seronegative women. RESULTS: Twenty of 1403
seronegative women in the first period (1.43%), 19 of 3605 women in the second
period (0.53%) and 8 of 8492 in the third period (0.09%) seroconverted during
pregnancy. The first prevention campaign reduced the seroconversion rate by 63%
(preduction rate of 92% compared to the seroconversion rate in the first period
(pis very effective in the prevention of toxoplasmosis during pregnancy. Primary
prevention should not only be based on education about preventive measures given
by physicians, but these guidelines should be reiterated during antenatal classes
and leaflets distributed containing written recommendations on the nature of the
disease and its avoidance.