Diagnosis of congenital cerebral toxoplasmosis by detection of low avidity specific IGG antibodies in cerebrospinal fluid

ABSTRACT

To assess the role of congenital toxoplasmosis as a causative agent of the CNS disorders in human off springs, 105 newborns, infants, preschool and school children with these disorders were observed. They consisted of three groups. The first were 24 newborns and infants to mothers seroconverted during pregnancy, the second; 39 newborns and infants whose immunocompromised mothers were Toxoplasma chronically infected before pregnancy, the third, 42 children who were clinically free at birth but presented with CNS disorders 4-9 years later; their mothers were with chronic Toxoplasma seropositivity at the time of the survey. Anti-Toxoplasma IgG antibodies were sought in the sera of mothers and sera and CSF of the off springs. Specific intrathecal IgG antibody production was estimated by calculating Goldman Witmer Coefficient [C] and by calculating the CSF to serum antibody avidity ratio [AR] exploiting an ELISA that included dissociation of antigen-antibody complexes with 6 Mure a solution. C value > 8 and AR value < 0.5 were detected in 5 [20.8%] members of the first group, 3 [7.6%] of the second and 4 [9.5%] of the third. These values corresponded with the response to specific therapy. The antibody avidity in the diagnosed newborn sera [children [who manifested the disease after the newborn period. Apart from the early serological evidence of congenital toxoplasmosis, CSF analysis by avidity ELISA can offer a valuable aid to make specific diagnosis of congenital cerebral toxoplasmosis. This helps to increase the chance of picking up the affected children in which specific therapy can be established earlier, so as to avoid shunts being performed