An outbreak investigation of parechovirus-A3 in a newborn nursery

Objective:To investigate parechovirus-A3 (PeV-A3) transmission in a newborn nursery, after encountering 3 neonates with fever and rash. Design:An observational study. Setting:At a newborn nursery at the general hospital in Hyogo, Japan. Participants:Symptomatic neonates and their family members, and asymptomatic neonates born during the same period. Methods:PCR assays for PeV-A and genotyping were used for the investigation of PeV-A3. Preserved umbilical cords were used to identify the route of transmission. Results:PeV-A3 infection was confirmed in the three symptomatic neonates. The index case had fever and rash, and the 2 neonates treated later became symptomatic and had serum, cerebrospinal fluid, and stool specimens that were positive for PeV-A3 on PCR. The umbilical cord of the index case was positive for PeV-A3 on PCR. The family members of the index case, including the mother, were asymptomatic before delivery. The older sister and cousin of the PeV-A3-infected neonate had positive PCR results. The sequence analysis suggested 2 possible transmission routes: vertical and horizontal transmission in a newborn nursery and/or a family outside the hospital. The incubation period of PeV-A3 infection was estimated to be 1-3 days (maximum, 7 days). Conclusion:Horizontal transmission of PeV-A3 was confirmed in a newborn nursery. Vertical transmission was suggested by the detection of RNA in an umbilical cord sample from the index case. These observations indicate that PeV-A3 can be horizontally transmitted in a newborn nursery and that special caution is required to prevent healthcare-associated transmission of PeV-A3.