Congenital toxoplasmosis in southeastern Brazil: results of early ophthalmologic examination of a large cohort of neonates.

OBJECTIVE: To report results of early ophthalmologic examinations in a large cohort of newborns with congenital toxoplasmosis (CT) after neonatal screening. DESIGN: Cross-sectional analysis of a cohort. PARTICIPANTS: A total of 178 newborns with confirmed CT from 146,307 screened babies (95% of live births) from Minas Gerais state, southeastern Brazil. METHODS: From November 2006 to May 2007, newborns underwent neonatal screening by immunoglobulin (Ig)M capture of dried blood samples. On all positive or suspected cases, confirmative serology was performed on babies and their mothers. Congenital toxoplasmosis was confirmed in newborns who had IgM and/or IgA and IgG, or IgG associated with suggestive ocular lesions (with IgM and IgG in the mother). Ophthalmologic evaluation consisted of indirect ophthalmoscopy with a lid speculum. Pediatric examination and radiologic studies of the central nervous system were also performed. In selected cases, biomicroscopy of the anterior segment, fundus photographs, or ultrasonography (B-scan) was performed. MAIN OUTCOME MEASURES: Prevalence of retinochoroidal lesions, either cicatricial or active, and their location and associated findings, such as vascular sheathing, hemorrhage, vitreous opacities, and retinal detachment, were evaluated. The occurrence of cataract, microphthalmia, microcephaly, intracranial calcification, and hydrocephalus was also recorded. RESULTS: Of 146,307 neonates screened, 190 had CT, yielding a prevalence of 1 in 770 live births, of whom 178 (93.7%) underwent standardized ophthalmologic examination at an average age of 55.6+/-16.6 days. Of these 178 infants, 142 (79.8%) had retinochoroidal lesions consistent with CT in at least 1 eye. Bilateral involvement was noted in 113 patients (63.5%). Macular involvement was seen in 165 eyes (46.3%) of 111 patients (62.4%). Active lesions were observed in 142 eyes (39.9%) of 85 patients (47.8%). These lesions were located in the macula of 75 eyes (21.1%) and were associated with retinal vascular sheathing in 44 eyes (12.4%). CONCLUSIONS: A high prevalence of CT was encountered (1/770) with high rates of early retinochoroidal involvement ( approximately 80%) and many active lesions (in approximately 50%), indicating a possibly more severe ocular involvement by CT in Brazil than in other parts of the world. The hypotheses of higher parasite virulence and increased individual susceptibility are being currently investigated.

Association between IgG subclasses against Toxoplasma gondii and clinical signs in newborns with congenital toxoplasmosis.

BACKGROUND: The aim of this study was to evaluate the association between clinical signs of congenital toxoplasmosis and IgG subclasses found in newborns participating in the Minas Gerais State Neonatal Screening Program. METHODS: Neonates with confirmed congenital toxoplasmosis underwent standardized ophthalmologic evaluation, neuroimaging studies and hearing assessment, as well as enzyme-linked immunosorbent assay testing for total IgG and its subclasses (IgG1, IgG2, IgG3 and IgG4) against soluble (STAg) and recombinant (rSAG1 and rMIC3) antigens of Toxoplasma gondii. RESULTS: Newborns with congenital toxoplasmosis but without ocular lesions were more likely to present anti-rMIC3 total IgG when compared with those newborns with active or cicatricial retinochoroidal lesions. Detection of anti-rMIC3 IgG2 and IgG4 was associated with presence of retinochoroidal lesions and intracranial calcifications, with higher mean reactivity index values than unaffected newborns with congenital toxoplasmosis. Anti-STAg IgG3 was associated with newborns without neurologic damage. CONCLUSIONS: Specific subclasses of IgG antibodies reacting with recombinant antigens of T. gondii may serve as biomarkers of neurologic and ocular changes in newborns with congenital toxoplasmosis.