Maternal infection with Listeria can result in chorioamnionitis, premature labor, spontaneous abortion, or stillbirth. Fetal infection can occur via transplacental transmission. Vertical transmission also can occur from mother to infant via passage through an infected birth canal or ascending infection through ruptured amniotic membranes. Early onset neonatal listeriosis usually is associated with sepsis or meningitis. Late onset neonatal listeriosis frequently presents with purulent meningitis.
Listeriosis often involves many organs with microabscesses or granulomas.
A disseminated rash with small pale nodules that are granulomas histologically characterize granulomatosis infantisepticum. Beyond the neonatal period, most children with Listeria infections have an underlying immunodeficiency or are immunocompromised. Older children with Listeria infections frequently develop meningitis. Approximately 2000 cases per year are reported. Lower incidence figures have been reported in Australia, England, and Denmark.