Patterns in respiratory virus infections in children presenting to outpatient clinics with acute upper respiratory tract infections

Abstract

BACKGROUND: Respiratory viruses cause acute respiratory diseases in all age groups and are an important cause of hospitalizations and deaths every year in Hong Kong. These viruses often result in a broad and overlapping spectrum of symptoms. Coinfection with different respiratory viruses is well documented, but the implication has not been clarified to date. This study aimed to characterize the clinical presentation of the most frequently detected respiratory viruses and identify patterns in respiratory virus circulation among children in Hong Kong. MATERIALS AND METHODS: Children presenting to an outpatient clinic with acute upper respiratory tract infections were recruited between January 2007 and September 2010. At recruitment, their clinical signs and symptoms were recorded, and a nasal swab and a throat swab were collected and pooled for testing. Swabs were tested using the xTAG multiplex assay, which can detect 17 respiratory viruses. RESULTS: Among 2099 specimens collected from eligible children during the 4-year study period, 1348 (64.2%) were positive for any respiratory virus, and 80 (5.9%) specimens were positive for coinfection (including 2 specimens positive for 3 viruses). The most frequently detected viruses were enterovirus/rhinovirus (23.4%) and influenza A (19.4%). The most commonly detected viruses among children aged 6-15 y were influenza A and B and human coronavirus, while many different respiratory viruses were frequently detected in children below 6 y of age. The various respiratory viral infections were all associated with similar patterns in symptoms, except influenza A/B and adenovirus infections, which were associated with higher mean body temperature at presentation. Around 70% of influenza A/B infections met the “influenza-like illness” (ILI) case definition (fever ≥37.8°C plus cough or sore throat) compared with approximately 40%-60% of infections with other respiratory viruses. CONCLUSIONS: Influenza A and B and human coronavirus were more commonly detected in older children with acute upper respiratory tract infection. There was no clear annual seasonality in detection of most respiratory viruses. Many of the non-influenza viruses led to illness meeting the ILI case definition, with potential implications for the interpretation of ILI data for influenza surveillance.