[Prospective evaluation of the risk of congenital toxoplasmosis. II. Further data on the immune response during pregnancy].

The indirect immunofluorescence test was carried out in 500 pregnant women in urban and rural areas, with a view to following conversion to seronegative values. The evolution of the immune background in infection with T. gondii was followed up by comparative analysis of the seroepidemiological data obtained in 1976 and 1977. It was found that:--Variations in the intensity of endogenous and exogenous factors bring about changes in the frequency and intensity of the immune response in toxoplasmosis.--Postnatal evolution of the child can be correlated with the age of pregnancy when seroconversion accurred and with the intensity of the latter.--The predominance of seroconversion in the 6th and 7th month of pregnancy and negativation of some of the responses during pregnancy suggest the need of an additional serological control during these months.--The effect of optimal conditions during springtime resulted in seasonal appearance of seroconversions, offering an additional orientation.--In the neonates of seropositive mothers no cases of manifest disease were observed; the presence of infection has to be subsequently confirmed or invalidated.