Background and objective: The aim of this study was to know: 1) the prevalence of antibodies against toxoplasma in pregnant women, 2) the incidence of primary infection during pregnancy and 3) the prevalence of congenital toxoplasmosis.
Subjects and method: Seroprevalence was prospectively analyzed in 16,362 pregnant women visited in 8 hospitals and 2 day care centers in Barcelona during 1999. Each participant laboratory included their own assays to detect toxoplasma-specific immunoglobulins IgM, IgA, IgG and IgG avidity antibodies. In case of positive specific IgM, a second serum sample was requested, which was processed in parallel with the first one. Three infection stages were defined: acute, possible and past (latent). Congenital infection was determined prenatally by polymerase chain reaction (PCR) in amniotic fluid or postnatally by serology in the newborn.
Results: Seroprevalence was 28.6%. The incidence of primary infection during pregnancy was 1.02/1,000 susceptible pregnant women. Nine women out of 12 with an acute toxoplasma infection became seroconverted during their pregnancies and five of them had infants with congenital toxoplasmosis (vertical transmission: 41.6%). All four children born alive had no symptoms during their follow-up.
Conclusions: In this study, the prevalence of toxoplasmosis was low. Acute toxoplasmosis was detected mainly by seroconversion during pregnancy. The frequency of maternal-fetal transmission was near half of cases.