We compared the clinical and demographic features of children with lower respiratory tract infection (LRI) caused by human metapneumovirus (HMPV), respiratory syncytial virus (RSV) and influenza A virus and sought to determine whether coinfection by HMPV and other respiratory viruses leads to increased disease severity.
Nasal wash specimens were prospectively obtained from 516 children hospitalized for LRI during a 1-year period and tested for the presence of HMPV by reverse transcription-polymerase chain reaction and for RSV and influenza A by direct immunofluorescence.
HMPV was detected in 68 (13%) patients and was the third most common viral pathogen; 16 of 68 HMPV-positive children (24%) had coinfection with other respiratory viruses (HMPVco).
HMPV patients were older than RSV patients (17.6 ± 16.8 months versus 10.5 ± 11.8 months, P = 0.02). HMPV was associated with wheezing and hypoxemia at a rate similar to that of RSV and higher than that of influenza A. Atelectasis was more common among HMPV (40%) than among RSV and influenza patients (13%, P < 0.05 for each). HMPV infection was more often associated with a diagnosis of pneumonia than RSV and influenza A and was more often associated with a diagnosis of asthma and less often associated with a diagnosis of bronchiolitis than RSV infection (P < 0.05 for each), even when corrected for age. Children with HMPVco had a higher rate of gastrointestinal symptoms but did not show a more severe respiratory picture.
The clinical pattern of HMPV more closely resembles that of RSV than that of influenza A LRI, yet the differences in age, radiographic findings and clinical diagnosis suggest that HMPV pathogenesis may differ from that of RSV.
From the *Department of Clinical Microbiology and Infectious Diseases, Hadassah University Hospital, Jerusalem, Israel; and the †Pediatric Infectious Diseases Unit and the ‡Clinical Virology Laboratory, Soroka University Medical Center and the Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Accepted for publication November 11, 2005.
Supported by a grant from the Israeli Ministry of Health; conducted in the Straus Molecular Diagnostics Core Facility, supported by a grant from the Samuel and Dora Straus Foundation from New York; and at the Pediatric Infectious Disease Unit of the Soroka University Medical Center, supported by a grant from Wyeth Pharmaceuticals, Inc.
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