[Evolution of immunity to Toxoplasma gondii in an apparently healthy human population].

In order to detect the evolution of the immune background in infections with T. gondii, investigations were carried out by the indirect immunofluorescence test in 231 apparently healthy subjects, belonging to different age-groups, from three rural localities in Moldavia. A second serologic test was performed after various intervals (6 months, 16 months, 5 years). The results showed that:--The evolution of the immune background appears to be conditioned by the factor time, significant variations only being recorded after longer intervals (5 years).--The immune background is relatively stable and durable; the state of individual immunity, however, although durable appears to be limited in time.--Serologic conversion per age-groups differs, new cases appearing in principle in the 5--9 years age-group and the negative results being obtained in the 10--14 years age-group and after the age of 15 years.--The 5--9 years age-group presents a particular reactivity, evidenced by the high proportion of ascending titers.