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Key Features

Essentials of Diagnosis

  • Diffuse wheezing and tachypnea following upper respiratory symptoms in an infant (bronchiolitis)

  • Epidemics in late fall to early spring (January–February peak)

  • Hyperinflation on chest radiograph

  • Detection of RSV antigen or nucleic acid in nasal secretions

General Considerations

  • Accounts for more than 70% of cases of bronchiolitis and 40% of cases of pneumonia

  • Virus is ubiquitous in early childhood

  • Outbreaks occur each year, and attack rates are high

    • 60% of children are infected in the first year of life

    • 90% by age 2 years

  • Progressive severe pneumonia may develop in immunosuppressed patients

  • Children with congenital heart disease with increased pulmonary blood flow, children with chronic lung disease (eg, cystic fibrosis), and premature infants younger than age 6 months (especially when they have chronic lung disease of prematurity) are also at higher risk for severe illness

Clinical Findings

Symptoms and Signs

  • Low-grade fever may be present

  • Classic disease is bronchiolitis, characterized by

    • Diffuse wheezing

    • Variable fever

    • Cough

    • Tachypnea

    • Difficulty feeding

    • Cyanosis (in severe cases)

  • Hyperinflation, crackles, prolonged expiration, wheezing, and retractions are present

  • Liver and spleen may be palpable but not enlarged

  • Apnea, poor feeding, and lethargy may be presenting manifestations, especially in premature infants, in the first few months of life

  • Infection in older children is more likely to cause tracheobronchitis or upper respiratory tract infection

Differential Diagnosis

  • Bronchiolitis

  • Parainfluenza, rhinovirus, and especially human metapneumovirus

  • Chlamydial pneumonitis

  • Cystic fibrosis

  • Bacterial superinfection (neutrophilia)

  • Pertussis (lymphocytosis)


Laboratory Findings

  • Fluorescent antibody staining or ELISA

    • Rapidly detects RSV antigen in nasal or pulmonary secretions

    • Requires only several hours

    • More than 90% sensitive and specific

  • Real-time polymerase chain reaction (PCR)

    • More sensitive than antigen testing but is more expensive

    • Multiplexed to detect four or more viral respiratory pathogens in the same assay

  • Rapid tissue culture methods

    • Take 48 hours and have comparable sensitivity

    • Require a carefully collected and handled specimen


  • Diffuse hyperinflation and peribronchiolar thickening are most common

  • Atelectasis and patchy infiltrates also occur in uncomplicated infection, but pleural effusions are rare

  • Consolidation (usually subsegmental) occurs in 25% of children with lower respiratory tract disease


  • Children who are very hypoxic or cannot feed because of respiratory distress must be hospitalized and given humidified oxygen as directed by oxygen saturation, and given tube or intravenous feedings

  • Antibiotics, decongestants, and expectorants are of no value in routine infections

  • a trial of bronchodilator therapy is given to determine response and is subsequently discontinued if there is no improvement.

  • Racemic epinephrine occasionally works when β-agonists fail. This therapeutic trial should only be undertaken in a hospital setting and care taken to ...

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