Age-associated prevalence of Toxoplasma gondii in 8281 pregnant women in Poland between 2004 and 2012

This study aimed to describe Toxoplasma gondii prevalence in Polish pregnant women and the incidence rates of congenital infections in their neonates observed between 2004 and 2012. Serological tests for T. gondii-specific IgG and IgM antibodies were performed on serum samples of 8281 pregnant women treated at the Polish Mother's Memorial Hospital Research Institute in Lodz. The yearly seroconversion rate for T. gondii IgG antibodies was estimated using a mathematical model to determine the dependency between age and prevalence. Mean prevalence of IgG antibodies between 2004 and 2012 in pregnant women was 40 center dot 6% [95% confidence interval (CI) 39 center dot 6-41 center dot 7] and increased with age with a yearly seroconversion rate of 0 center dot 8% (95% CI 0 center dot 6-1 center dot 0, P<0 center dot 001). Assuming a T. gondii materno-fetal transmission rate of 30% gave an estimate of 1 center dot 80/1000 neonates as congenitally infected. The increased mean age (28 center dot 7 vs 26 center dot 7 years, P<0 center dot 001) of pregnant women was probably the most important factor in abolishing the effect of falling prevalence rates.