Is bronchitis contagious?

Is Bronchitis Contagious?

Yes, acute bronchitis is contagious because it is caused by infectious agents—primarily respiratory viruses in over 90% of cases—that spread from person to person through respiratory droplets. 1

Understanding the Contagious Nature

Acute Bronchitis: Highly Contagious

Acute bronchitis is an infectious disease that spreads between people, particularly during winter months when respiratory infections are prevalent. 1

• Viral transmission accounts for 90-95% of acute bronchitis cases, making it highly contagious through respiratory droplets when infected individuals cough or sneeze 1, 2

• Common contagious viruses causing acute bronchitis include:

  • Influenza A and B (highly contagious with rapid community spread) 1
  • Respiratory syncytial virus (RSV) with attack rates as high as 61-75% in households and institutional settings 1
  • Parainfluenza, coronavirus, adenovirus, and rhinoviruses 1

• Bacterial causes (5-10% of cases) are also contagious, including Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Bordetella pertussis 1

• Pertussis (Bordetella pertussis) is particularly contagious, and 25% of adults with nonspecific lower respiratory symptoms may actually have pertussis, which poses significant transmission risk to unimmunized infants 3

Chronic Bronchitis: Not Contagious (But Exacerbations Can Be)

Chronic bronchitis itself is NOT contagious because it is caused by prolonged exposure to pulmonary irritants, primarily cigarette smoke, not by infectious agents. 1

• Chronic bronchitis is defined as cough with excessive mucus production on most days for 3 consecutive months over 2 successive years, caused by chronic irritation rather than infection 1

• However, acute exacerbations of chronic bronchitis ARE contagious when triggered by viral or bacterial infections 1

• During acute exacerbations, patients with chronic bronchitis have greater frequency of acute respiratory infections than healthy individuals, with viral infections found in approximately one-third of episodes 1

• Common infectious triggers during exacerbations include:

  • Rhinovirus, coronavirus, influenza B, and parainfluenza (viral—contagious) 1
  • Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae (bacterial—contagious) 1, 4

Clinical Implications for Transmission

When influenza is circulating in the community, the presence of both cough and fever within 48 hours of symptom onset strongly predicts influenza infection, which is highly contagious. 1

RSV outbreaks demonstrate the highly contagious nature of viral bronchitis, with attack rates of 75% in households with small children and in geriatric settings, with 96% of infected individuals reporting intense coughing. 1

Key Distinction for Patient Communication

Describing acute bronchitis as a "chest cold" rather than "bronchitis" may be clinically useful, as patients are less likely to expect antibiotics for a chest cold (11%) compared to bronchitis (44%), even though both conditions are equally contagious and viral in nature 1