Clinical meaning
RSV is the most common cause of bronchiolitis and pneumonia in infants under 1 year. The virus infects bronchiolar epithelial cells, causing necrosis, sloughing of cells into the airway lumen, peribronchiolar inflammation, and mucus production. The resulting airway obstruction causes air trapping, wheezing, and respiratory distress. Infants are particularly vulnerable because their small airways are easily obstructed. RSV is transmitted by contact with infected secretions and survives on surfaces for up to 6 hours. Treatment is primarily supportive — bronchodilators and corticosteroids are NOT recommended for routine RSV bronchiolitis. Palivizumab (Synagis) is a prophylactic monoclonal antibody for high-risk infants.
Exam relevance
Risk factors: - Age <6 months (highest risk for severe disease) - Prematurity (<35 weeks gestational age) - Congenital heart disease - Chronic lung disease of prematurity (BPD) - Immunodeficiency - Down syndrome - Daycare attendance - Siblings in school - Secondhand smoke exposure - Crowded living conditions
Diagnostics: - Rapid antigen detection test (nasal wash or nasopharyngeal aspirate) - PCR (most sensitive test for RSV) - Clinical diagnosis based on seasonal bronchiolitis presentation in infants - Chest X-ray: hyperinflation, peribronchial thickening, atelectasis (not routinely indicated) - Pulse oximetry for continuous SpO2 monitoring - CBG or ABG if respiratory failure suspected