Is Bronchitis Contagious?
Yes, acute bronchitis is highly contagious because it is caused by respiratory viruses in over 90% of cases, and these viruses spread readily through respiratory droplets and close contact. 1
Understanding the Infectious Nature of Acute Bronchitis
Viral Causes (Highly Contagious)
Respiratory viruses account for more than 90% of acute bronchitis cases and are transmitted person-to-person through respiratory droplets. 1 The specific contagious viruses include:
- Lower respiratory tract viruses: Influenza A and B, parainfluenza, and respiratory syncytial virus (RSV) are the most common causes 1
- Upper respiratory tract viruses: Coronavirus, rhinovirus, and adenovirus also cause acute bronchitis 1
- RSV is particularly contagious, with attack rates as high as 61-75% in households with small children and institutional settings 1
- Influenza spreads rapidly during seasonal outbreaks, causing considerable morbidity in the general population 1
Bacterial Causes (Less Common, Variable Contagiousness)
Only 5-10% of acute bronchitis cases have bacterial causes, and these have varying degrees of contagiousness: 1
- Bordetella pertussis (whooping cough) is highly contagious 1
- Mycoplasma pneumoniae and Chlamydophila pneumoniae can spread in community outbreaks, particularly in military personnel and college campuses 1
- Common bacteria like Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis do NOT cause acute bronchitis in healthy adults without underlying lung disease 1
Transmission and Contagious Period
The contagious period begins during the incubation phase (typically 4-6 days for RSV) and continues while symptoms are present. 2 Key transmission facts:
- Spread occurs through respiratory droplets from coughing and sneezing 2
- Standard precautions are essential: hand hygiene, surface cleaning, and avoiding contact with sick individuals 2
- Healthcare workers are at high risk during outbreaks of highly infectious agents like SARS-coronavirus 1
Chronic Bronchitis: Not Contagious
Chronic bronchitis itself is NOT contagious because it results from prolonged exposure to pulmonary irritants, primarily cigarette smoke, not from infectious agents. 1 However:
- Patients with chronic bronchitis can develop acute exacerbations triggered by contagious viral infections (rhinovirus, coronavirus, influenza, parainfluenza) 1
- During these acute exacerbations, the viral component is contagious to others 1
Clinical Implications for Infection Control
Patients with acute bronchitis should be advised to:
- Stay home from work or school while symptomatic to prevent transmission 2
- Practice respiratory hygiene (covering coughs, hand washing) 2
- Understand that the illness typically lasts 2-3 weeks, with cough being the predominant symptom 3, 4
Important caveat: While the infectious agent causing bronchitis is contagious, not everyone exposed will develop bronchitis—some may develop only upper respiratory symptoms or remain asymptomatic. 1