Upper respiratory virus detection without parent-reported illness in children is virus-specific

Background Viral upper respiratory tract infection (vURI) may or may not present with a cold/flu-like illness (CFLI). Objectives For common upper respiratory viruses that cause vURIs, to determine the relative frequencies of virus detection by PCR in subjects with and without CFLIs. Study design Prospective follow-up of 170 children aged 1–8.6 years through the CFLI season by daily parental diary for CFLI episodes and nasal secretion sampling using PCR assays for adenovirus, coronavirus (types 229E and OC43), influenza virus (types A and B), parainfluenza (types 1–3) virus, rhinovirus, and respiratory syncytial virus (RSV). Results Virus was detected in 415 of 956 independent assays: 425 CFLI episodes and 531 non-CFLI periods were sampled; samples from 270 (64%) CFLI episodes and 145 (27%) non-CFLI periods contained virus detected by PCR. Rhinovirus was most frequently detected at 64%, followed by mixed viruses at 12%, RSV at 7%, and the other viruses at 3–5% of all detections. About 85% of RSV, influenza A and adenovirus detections were associated with a CFLI, whereas less than 62% of other virus detections were associated with CFLI. Conclusions The frequency of PCR virus detection without CFLI was different among viruses. This introduces virus-specific biases to estimating the frequencies of specific complications attributable to a vURI when ascertained by CFLI identification.