Respiratory syncytial virus

Background

Microbiology

• Single-stranded, enveloped RNA virus in the Pneumoviridae subfamily of the Paramyxoviridae family
• Two antigenic groups, A and B

Epidemiology

• Worldwide distribution
• In Canada and US, more common in late fall to early spring, but can occur at any time
• Most common cause of bronchiolitis in children
• Spread via droplets, either person-to-person or via fomites
  • Typically inoculated into respiratory or ocular mucosa rather than inhaled
• Infection does not generate persistent immunity

Clinical Manifestations

• Incubation period of 3 to 5 days (up to 8 days)

Children

• Generally starts with an upper respiratory tract infection ± fevers and otitis media
• Then can progress to bronchiolitis, pneumonia, tracheobronchitis, and, rarely, croup
  • Highest risk for lower respiratory infections are with the first infection, age less than 6 months, and underlying cardiac or lung disease
  • Highest risk for requiring hospitalization is premature infants and those with chronic lung disease, congenital heart disease, immunosuppression, and neuromuscular disease
• Wheezing and increased work of breathing are common and cough becomes prominent
• Bronchiolitis may involve inspiratory and expiratory obstruction
• Hypoxia necessitates hospitalization, and may fluctuate, and can also have apnea

Outcomes and sequelae

• Cough may last for 4 or more weeks, despite resolution of the infection
• Recurrent infections are common
• May have persistent wheezing into adolescence

Adults

• More common in people who work with children and military recruits living in barracks
• Highest risk for severe disease includes the elderly, patients with COPD, and immunocompromised patients
• Immunocompromised patients include solid-organ and hematologic transplant patients and those on chemotherapy
  • Much higher mortality
  • Bronchiolitis obliterans syndrome can be a complication in lung transplant patients with RSV pneumonia

Diagnosis

• Most often with PCR
• Serology not generally helpful

Management

• Supportive care
  • Can use puffers and steroids for bronchiolitis with wheezing, but not clear that they are helpful in children
  • Monitor for development of bacterial superinfection
• Hospitalized children may benefit from inhaled ribavirin, though the benefit is unclear
• In high-risk patients with hematologic malignancies, hematologic transplants, or solid-organ transplants, treat with ribavirin
• In the highest-risk group of patients, those with allogeneic stem cell transplantation who present with pneumonia, add IVIg

Prevention

• Palivizumab is indicated for some high risk groups of infants in order to prevent severe disease1
  • Children with hemodynamically significant CHD or CLD if they are <12 months of age at the start of RSV season
  • Preterm infants born before 30+0 weeks’ GA who are <6 months of age at the start of RSV season, it is reasonable (but not essential) to offer palivizumab
  • Infants in remote communities who would require air transportation for hospitalization born before 36+0 weeks’ GA and <6 months of age at the start of RSV season should be offered palivizumab
  • Can be considered in patients up to 24 months old if they are still on home oxygen, have had a prolonged hospitalization for severe pulmonary disease or are severely immunocompromised