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Three-Year Study of Viral Etiology and Features of Febrile Respiratory Tract Infections in Japanese Pediatric Outpatients

Hara, Michimaru MD*; Takao, Shinichi PhD; Shimazu, Yukie PhD; Nishimura, Tatsuo MD

The Pediatric Infectious Disease Journal: July 2014 - Volume 33 - Issue 7 - p 687–692
doi: 10.1097/INF.0000000000000227
Original Studies

Background: For most febrile respiratory tract infections (RTIs) in children, the causative pathogen is never identified. We sought to identify the causative pathogen in individual cases of pediatric outpatient with RTIs and to determine whether particular clinical features of RTIs are associated with particular viruses.

Methods: Over 3 years, we prospectively collected nasopharyngeal aspirate specimens from individual pediatric outpatients with an RTI accompanied by persistent fever (>3 days, ≥38.0°C) and peak temperature ≥39.0°C. Two methods—(1) viral culture for respiratory viruses and (2) real-time polymerase chain reaction (PCR) assays identifying 9 different respiratory viruses and 2 respiratory bacteria—were used to test specimens.

Results: For 495 specimens, viral culture and real-time PCR assays together identified at least 1 pathogen in 83.0% and ≥1 viruses alone in 79.4%. These 2 methods identified 138 children with respiratory syncytial virus, 66 with human metapneumovirus, 73 with parainfluenza viruses, 124 with adenovirus, 23 with rhinovirus, 38 with enterovirus, 11 with influenza type C virus, 15 with Mycoplasma pneumoniae and 3 with Chlamydophila pneumoniae; the coinfection rate was 19.7% among all infections. Among the patients with single-pathogen infections, the rate of lower RTI was 37.6% for respiratory syncytial virus, 40.7% for human metapneumovirus, 18.2% for parainfluenza viruses and 2.2% for adenovirus (P < 0.01).

Conclusions: Viral culture and real-time PCR assays were used together to identify causative pathogens in 83% of febrile outpatient children with RTI; specific viruses were associated with particular clinical diagnoses.

Supplemental Digital Content is available in the text.

From the *Hara Pediatric Clinic, Hiroshima, Japan; Center for Public Health and Environment, Hiroshima Prefectural Technology Research Institute, Hiroshima, Japan; and Nishimura Pediatric Clinic, Osaka, Japan.

Accepted for publication December 2, 2013.

The authors have no funding or conflicts of interest to disclose.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website (

Address for correspondence: Shinichi Takao, PhD, Center for Public Health and Environment, Hiroshima Prefectural Technology Research Institute, 1-6-29 Minami-machi, Minami-ku, Hiroshima 734-00076, Japan. E-mail:

© 2014 by Lippincott Williams & Wilkins, Inc.