To report results of early ophthalmologic examinations in a large cohort of newborns
with congenital toxoplasmosis (CT) after neonatal screening.
Cross-sectional analysis of a cohort.
A total of 178 newborns with confirmed CT from 146,307 screened babies (95% of live
births) from Minas Gerais state, southeastern Brazil.
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.
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.
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%).
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.