Impact of rapid viral testing for influenza A and B viruses on management of febrile infants without signs of focal infection

Background: The objective of this study was to assess the effect of rapid testing for influenza virus on management of febrile young infants. Methods: During 2 influenza seasons (November to December 2003 and December 2004 to February 2005), we studied prospectively infants who were 0 to 36 months of age who presented to the emergency department (ED) with fever in the absence of signs of focal infection. The Directigen Flu A+B test was used to determine infection with influenza virus types A or B. Confirmatory viral cultures were not done. Results: Rapid influenza testing was performed in 206 infants and 84 (40.7%) of them were influenza-positive. Infants with a positive and a negative influenza test showed a similar mean (standard deviation) age (6.86 [6.3] versus 6.55 [6.8] months) and mean temperature (39.38 degrees C [0.6] versus 39.32 degrees C [0.8]), but there were significant differences (P < 0.01) in the percentage of patients undergoing blood tests (33.3% versus 100%), urinalysis (80.9% versus 100%), chest roentgenogram (14.2% versus 32%), cerebrospinal fluid analysis (1.33% versus 21.3%), mean length of stay in the ED (116.2 [75.5] versus 192.9 [76.3] minutes), admission to the ED observation ward (8.3% versus 21.3%), inpatient care (2.3% versus 16.4%) and antibiotic treatment (0% versus 38.5%). All positive bacterial cultures occurred among influenza-negative patients. Conclusions: The inclusion of rapid influenza testing for the evaluation of febrile young infants without signs of focal infection during influenza season decreases the need for additional studies and reduces the length of stay in the ED, the use of antibiotic treatment and unnecessary hospitalizations.