Nosocomial viral infections in the neonate

INTRODUCTION

Although the published incidence of viral neonatal nosocomial infection is considerably lower than bacterial nosocomial infection [1], significant mortality and morbidity occur in the estimated one percent of infants who acquire a viral infection after admission to the neonatal intensive care unit (NICU) [2].

The epidemiology, and the viruses and their clinical manifestations of neonatal nosocomial viral infection will be reviewed here.

EPIDEMIOLOGY

The incidence of neonatal nosocomial viral infections has probably been underestimated because viral studies are not routinely obtained in neonates. The lack of testing for viral infection is due to the overlap of clinical signs and symptoms of viral infections from other conditions seen in the critically ill neonate, the difficulty in obtaining laboratory confirmation of a viral infection, and the lack of effective therapeutic interventions. Published reports have generally focused upon outbreaks of viral infections in NICUs.

One retrospective Dutch study provided limited data on the incidence of viral infections in the NICU and the most commonly detected viruses [2]. The overall incidence of viral infections in 5,396 neonates admitted to a single NICU was 1 percent between 1992 and 2003. Of the 51 identified viral infections, three were due to intrauterine infections due to rubella, cytomegalovirus (CMV), and herpes simplex; the rest were thought to be acquired after admission to the NICU. The causative viral agents and their frequency included:

• Enterovirus and parechovirus — 20 cases (39 percent)
• Respiratory syncytial virus (RSV) — 15 cases (29 percent)
• Rotavirus — 5 cases (10 percent)
• CMV — 3 cases (6 percent)
• Parainfluenza virus — 2 cases (4 percent)
• Adenovirus — 2 cases (4 percent)
• One case each of rhinovirus infection and rubella infection