What are the symptoms of Respiratory Syncytial Virus (RSV) infection?

Symptoms of Respiratory Syncytial Virus (RSV) Infection

RSV infection presents with a spectrum of symptoms ranging from mild upper respiratory tract illness to severe lower respiratory tract disease, including bronchiolitis and pneumonia, with severity typically worse in high-risk populations such as infants, older adults, and immunocompromised individuals. 1

Common Symptoms of RSV Infection

• Upper Respiratory Tract Symptoms:

  • Runny nose 2
  • Cough 2
  • Fever 2
  • Nasal congestion 1

• Lower Respiratory Tract Symptoms:

  • Wheezing (particularly common in RSV infection) 1, 3
  • Rapid breathing (tachypnea) 1
  • Difficulty breathing 1
  • Chest retractions 3
  • Abnormal breath sounds 1

• Severe Manifestations:

  • Bronchiolitis (inflammation of small airways) 2
  • Pneumonia (lung infection) 2
  • Respiratory failure in severe cases 1
  • Apnea (particularly in premature infants) 1, 2

Symptoms by Population

In Infants and Young Children

• Irritability 3
• Poor feeding 3
• Lethargy 1
• Apnea (breathing pauses) - especially in premature infants or those younger than 2 months 1
• Brief resolved unexplained events (formerly called apparent life-threatening events) 1

In Older Adults

• More severe lower respiratory symptoms 4
• Higher risk of pneumonia 1
• Exacerbation of underlying chronic conditions (particularly respiratory and cardiac) 4
• Symptoms may be confused with other respiratory infections 4

In Immunocompromised Patients

• More prolonged viral shedding 1
• Higher risk of progression from upper to lower respiratory tract disease 1
• Increased risk of severe disease and mortality 1
• Lymphopenia (<100 cells/mm³) is associated with progression to lower respiratory tract disease 1

Clinical Course and Progression

• Most RSV infections begin with upper respiratory symptoms that may progress to lower respiratory tract involvement 1
• Typical duration is 1-2 weeks in otherwise healthy individuals 2
• Chest radiographs may appear normal despite significant lower respiratory symptoms and hypoxia 5
• The virus primarily replicates in the respiratory epithelium, causing characteristic syncytia formation (multinucleated giant cells) 1
• Natural immunity is short-lived, making reinfections common throughout life 6, 4

Diagnostic Considerations

• RSV symptoms can be indistinguishable from other viral respiratory infections, especially in neonates 1
• Diagnosis is confirmed through laboratory testing of respiratory secretions 1
• Rapid antigen detection tests have variable sensitivity (80-95%) 1
• Molecular diagnostic tests (PCR) are more sensitive for detection 5

Risk Factors for Severe Disease

• Age extremes (very young and elderly) 1, 4
• Chronic lung disease 1
• Congenital heart disease 1
• Immunocompromised status 1
• Down syndrome 1
• Chronic kidney or liver disease 1
• Residence in nursing homes or long-term care facilities 6

Warning Signs Requiring Medical Attention

• Difficulty breathing or rapid breathing 2
• Bluish color around lips or face (cyanosis) 3
• Severe cough 2
• Signs of dehydration 2
• Lethargy or excessive irritability 3
• Apneic episodes 1

RSV infection should be considered in the differential diagnosis for patients presenting with respiratory symptoms, particularly during seasonal outbreaks (typically December through March in the United States) 1. The clinical presentation varies widely based on age, underlying conditions, and immune status, with certain high-risk groups requiring closer monitoring due to increased risk of severe disease 1, 6.