Detection of respiratory syncytial virus RNA in blood of neonates by polymerase chain reaction.

During the winter season of 1994/1995, nasopharyngeal aspirates and blood samples of neonates who were admitted to the Neonatal Intensive Care Unit (NICU) (group 1) and infants with respiratory tract disease (group 2) were examined prospectively for the presence of respiratory syncytial virus (RSV). Examination of nasal washes were done by antigen detection and blood samples were tested by nested reverse transcription and polymerase chain reaction (RT-PCR). The results of the 41 neonates studied were as follows: 14/41 were positive for RSV antigen in nasal washes and for RSV-RNA in blood, 5/41 were only RSV antigen positive, 13/41 neonates had negative nasal washes; 6 had positive RT-PCR results in blood. In 9/41 cases only blood samples were available. Five of these were positive by RT-PCR testing. Group 2 included 20 infants hospitalized with respiratory tract disease, e.g., pneumonia, bronchiolitis, or Upper Respiratory Tract Infection (URTI). Eleven out of twenty were positive for RSV antigen in nasal washes and 6/20 were also positive for RSV-RNA in blood. The conclusion is that viremia may be a frequent occurrence in neonates and young children.