Probable congenital babesiosis in infant, new jersey, USA.

Only 2 neonates with transplacentally or perinatally acquired (congenital) babesiosis have been reported. We describe a probable third congenital case of babesiosis in a 26-day-old infant; transmission was determined on the basis of a blood smear from the infant (15% parasitemia) and serologic results from the infant and mother.