Respiratory Syncytial Virus Infection (RSV)

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Referral

Definition

Respiratory Syncytial Virus (RSV) is a common viral infection that affects the respiratory tract, especially in infants, young children, and older adults. It is a leading cause of bronchiolitis and pneumonia in young children.

Aetiology

RSV is an RNA virus from the Paramyxoviridae family. It spreads via respiratory droplets, direct contact with infected surfaces, and close personal contact.

Pathophysiology

RSV infects the epithelial cells of the respiratory tract, leading to:

  • Necrosis and sloughing of epithelial cells.
  • Mucus hypersecretion, causing airway obstruction.
  • Inflammatory response resulting in airway oedema and narrowing.
  • V/Q mismatch, leading to hypoxia.

Risk factors

  • Prematurity (<37 weeks gestation).
  • Infants under 6 months of age.
  • Congenital heart disease or chronic lung disease.
  • Immunosuppression.
  • Exposure to cigarette smoke.
  • Attendance at daycare centres.
  • Crowded living conditions.

Signs and symptoms

Symptoms:

  • Fever (low-grade in most cases).
  • Runny nose and nasal congestion.
  • Cough, which may worsen over days.
  • Wheezing or noisy breathing.
  • Poor feeding and lethargy in infants.

Signs:

  • Tachypnoea (rapid breathing).
  • Subcostal and intercostal recessions (increased work of breathing).
  • Nasal flaring in infants.
  • Fine inspiratory crackles and wheeze on auscultation.
  • Cyanosis in severe cases.

Investigations

RSV is primarily a clinical diagnosis, but investigations may be required in severe cases:

  • Pulse oximetry: assess oxygen saturation.
  • Nasal or throat swab:
    • RSV antigen detection or PCR to confirm diagnosis.
  • Chest X-ray: Indicated if pneumonia is suspected, showing:
    • Hyperinflation of lungs.
    • Peribronchial thickening.
    • Atelectasis in some cases.
  • Blood gas analysis: in severe cases, may show hypercapnia or hypoxaemia.

Management

Management is primarily supportive as there is no specific antiviral therapy for RSV in most cases:

1. Supportive Care:

  • Oxygen therapy: if SpO₂ <92%.
  • Fluids: NG tube or IV fluids if feeding is inadequate.
  • Minimal handling: to reduce distress and work of breathing.
  • Suctioning: to clear nasal secretions in infants.

2. Pharmacological Management:

  • Antipyretics: paracetamol for fever and discomfort.

3. Respiratory Support (if required):

  • High-flow nasal cannula (HFNC): for moderate respiratory distress.
  • CPAP or mechanical ventilation: for severe respiratory failure.

Referral

Refer to secondary care if any of the following are present:

  • Severe respiratory distress: increased work of breathing, including marked recessions.
  • SpO₂ persistently <92% despite oxygen therapy.
  • Apnoea or cyanosis episodes.
  • Poor feeding leading to dehydration.
  • High-risk infants: premature, chronic lung disease, or congenital heart disease.
 
RespiratorymypanotesRespiratory Syncytial Virus Infection, RSV