Epidemiology of toxoplasmosis among pregnant women in the Paris area.

A survey was performed using a sample of pregnant women selected at one of the biggest test centres in the Paris area. These women were serologically screened for toxoplasmosis between October 1981 and September 1983 (according to the prevention protocol for congenital toxoplasmosis established by the French health ministry). The prevalence rate of specific antibodies for toxoplasmosis was estimated from the 1074 women who were tested for the first time during the study. The prevalence rate among pregnant women in the Paris area was derived by direct standardization according to age and geographical origin. A standardized prevalence rate of 71% +/- 4% among French women, of 51.4% +/- 5% among immigrant women and a global adjusted prevalence rate of 67.3% +/- 3% for pregnant women in the Paris area was found. An incidence rate of 1.6% was estimated for the 2216 non-immune pregnant women included in the sample. There is no significant difference between the probabilities of seroconversion among French and immigrant women (2.3% +/- 1% and 1.6% +/- 0.8% respectively). Comparison of the data with previous study results show a decrease in the prevalence rate of specific antibodies for toxoplasmosis in the Paris area over the last 20 years that cannot be explained by changes in age and geographical origin. No data were available to support an aetiological hypothesis for a decrease in toxoplasma transmission to humans. Since immigration and a decrease in toxoplasma transmission to humans has led to a larger population of women at risk of infection during pregnancy in France, it is therefore important to perform studies to investigate risk factors and markers of acquired toxoplasmosis during pregnancy in order to improve the prevention of congenital toxoplasmosis.