Challenges in Diagnosis of Congenital Toxoplasmosis on Postimplementation of Minas Gerais Screening Program

Congenital toxoplasmosis is both prevalent and severe in Brazil. The Minas Gerais Congenital Toxoplasmosis Control Program (PCTC-MG) used prenatal and neonatal screening to identify neonates at risk for congenital toxoplasmosis. This study aimed to evaluate the clinical and laboratory parameters used to diagnose the disease in this population.

This retrospective cohort study included children with suspected congenital toxoplasmosis who participated in the PCTC-MG between 2013 and 2020.

A total of 347 children participated in the study; 228 had confirmed toxoplasmosis and 119 were excluded. The majority (314/347; 90.5%) underwent neonatal screening for IgM in filter paper (FP). Among these, 269/314 (85.7%) had positive or indeterminate results, with 186 (69.1%) confirmed infections, while 45/314 (14.3%) had nonreactive results, with 17 confirmed infections. There was an association between treatment during pregnancy (45/227; 19.8%) and a lower number of reagent IgM results in FP ( P = 0.002) and serum ( P = 0.001). A higher gestational age was associated with a higher proportion of IgM in the FP ( P = 0.001) and serum ( P = 0.004). Retinochoroiditis (73.2%; 167/228) and neurologic changes (36.9%; 75/203) were frequent in the infected children. The treatment decision was based on the presence of IgM/IgA (176/226; 77.9%), retinochoroiditis (45/226; 19.9%) or persistence/increase in IgG levels (4/226; 1.8%).

Screening with specific and sensitive serology identified most, but not all, children with congenital toxoplasmosis. Ophthalmologic evaluations and neuroimaging are mandatory in this context. The absence of IgM in the FP did not exclude the diagnosis.