pediatrics
Congenital Toxoplasmosis
Diagnosis of Congenital Toxoplasmosis
Serial IgG measurement (for maternal infection) Amniotic fluid polymerase chain reaction (PCR) testing (for fetal infection) Serologic testing, brain imaging, cerebrospinal fluid (CSF) analysis, ophthalmologic evaluation (for neonatal infection), and PCR testing of various body fluids or tissues Serologic testing is important in diagnosing maternal and congenital infection. Maternal infectionshould be suspected if women have one or more of the following: A mononucleosis-like syndrome and negative tests for Epstein-Barr virus, HIV, and cytomegalovirus (antibody or PCR) Isolated regional adenopathy not due to another cause (eg, HIV) Chorioretinitis Acute maternal infection is suggested by seroconversion or a≥4-fold rise between acute and convalescent IgG titers. However, maternal IgG antibodies may be detectable in the infant through the first year. Forfetal infection,PCR analysis of amniotic fluid is emerging as the diagnostic method of choice. There are numerous other serologic tests, some of which are done only in reference laboratories. The most reliable are the Sabin-Feldman dye test, the indirect immunofluorescent antibody (IFA) test, and the direct agglutination assay. Tests to isolate the organism include inoculation into mice and tissue culture, but these tests are not usually done because they are expensive, not highly sensitive, and can take weeks before yielding results. Forinfants with suspected congenital toxoplasmosis,serologic tests, MRI or CT imaging of the brain, CSF analysis, brain stem auditory evoked responses, and a thorough eye examination by an ophthalmologist should be done. CSF abnormalities include xanthochromia, pleocytosis, and increased protein concentration. The placenta is inspected for characteristic signs ofT. gondiiinfection (eg, placentitis). Nonspecific laboratory findings include thrombocytopenia, lymphocytosis, monocytosis, eosinophilia, and elevated transaminases. PCR testing of body fluids, including CSF, and tissues (placenta) can also be done to confirm infection. Some states in the US do routine newborn screening to detect specific toxoplasmosis IgM antibody using dried blood. 