Identifying the cause of serious viral infections in febrile young infants visiting the pediatric emergency department.

BACKGROUND

Serious viral infections (SVIs) are a frequent and worrisome cause of fever in infants aged <90 days. The present study aimed to clarify the distinction between SVIs, viremia, and respiratory infections.

METHODS

This study was a secondary analysis of data derived from a pre-COVID-19 registry of infants aged <90 days presenting with a fever to the emergency department at a tertiary pediatric hospital in Japan. Data on the patient characteristics, vital signs, clinical symptoms, physical examinations, and laboratory examinations were collected. Patients meeting the systemic inflammatory response syndrome (SIRS) criteria or having a serious infection were stratified into a viremia group or respiratory infection group for univariate analysis.

RESULTS

Among young infants aged <90 days presenting with febrile episodes (n = 321), 48 had a SVI. Of these, 28 and 20 were categorized into the viremia and respiratory infection groups, respectively. The mean age and body weight of the former group were significantly lower than those of the latter group (29.6 days vs. 54.6 days; 4007.1 g vs. 4976.8 g). The respiratory rate was higher in the viremia group (41.4/min vs. 35.3/min), whereas upper respiratory tract symptoms were more common in the respiratory infection group (3.6% vs. 60.0%). Laboratory examinations found a significant difference in the white blood cell count (7700/μL vs. 10,200/μL).

CONCLUSIONS

The present study found that viremia was associated with younger age and a higher respiratory rate than respiratory infections. Multicentric studies are needed to verify these preliminary findings.