Vertical transmission of hepatitis A resulting in an outbreak in a neonatal intensive care unit.

Vertical transmission of hepatitis A virus (HAV) has not been reported. From 25 October to 15 November 1989, 10 cases of symptomatic HAV infection occurred among neonatal intensive care unit (NICU) staff. Testing of other NICU staff and patients identified 4 infected infants. Hepatitis A among staff was associated with caring for 1 of these infants, infant A (relative risk [RR], undefined; P = .05). Risk of illness was greater for staff who did not routinely wash their hands after treating infant A for apnea and bradycardia (RR = 4.9; P = .02). Staff, infants, visitors, and transfused blood products could not be implicated as a source of infant A's infection. Infant A's mother, however, was diagnosed with hepatitis A 10 days after premature labor and delivery. Evidence suggests that infant A was infected by his mother before or during birth. HAV then spread within the NICU because of breaks in infection control precautions. To prevent future outbreaks, NICU staff should adhere rigorously to body substance isolation measures.