Congenital toxoplasmosis complicated by central diabetes insipidus in an infant with Down syndrome.

We describe an infant with the unusual combination of Down syndrome, congenital toxoplasmosis, and central diabetes insipidus. Hydrocephalus was documented by fetal ultrasonography at 36 weeks' gestation. He developed central diabetes insipidus as a neonate, followed by interstitial pneumonia, anemia, and hepatosplenomegaly. The patient's serum titer for Toxoplasma-specific IgM (ELISA) at 37 days after delivery was negative, but the Toxoplasma SAG1 gene was detected from the cells of the cerebrospinal fluid on the same day using the polymerase chain reaction (PCR) method. Congenital toxoplasmosis can contribute to the development of central diabetes insipidus in infants. PCR was useful in diagnosing congenital toxoplasmosis rapidly and accurately.