Respiratory Syncytial Virus (RSV) Disease

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)

Diagnosis

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

Imaging

• 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

Treatment

• 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 ...