[The status of infection with Toxoplasma gondii in the Swiss population: contribution of a seroepidemiologic study from the Zurich canton].

To obtain information on the seroprevalence of specific antibodies to Toxoplasma gondii at the level of the general population, a study was performed using 4300 serum samples: 3500 samples collected at the blood donor center of Zürich (individuals between 18 and > 65 years old), 500 serum samples from children referred to the University Children's Hospital of Zürich (between 1 month and 17 years old) and 300 maternal sera, collected at delivery (from a mother-child sera collection of the University Children's Hospital of Zürich). Samples were systematically collected by age- (5 years) and sex-groups (sex ratio 1:1), until the desired number was obtained. The crude seroprevalence of specific IgG anti-T. gondii was 52.4% (confidence interval at 95% [p < 0.05]: 50.9-53.9). There were no significant differences between males and females. The seroprevalence of the group of women of childbearing age (between 20 and 40) was 40%. The comparison of this value with the results obtained from 300 maternal sera from the mother-child collection revealed no significant difference between the two groups. On the basis of these results and assuming that the information obtained at the level of the general population in the region of Zürich is representative of Switzerland, it was possible to calculate the required sample size to initiate a national study on seroprevalence of the infection with T. gondii among women at time of delivery.