What is the primary cause of acute bronchitis?

Acute bronchitis is primarily caused by viral infections, making viral pathogens the leading contributors to this condition. The most common viruses associated with acute bronchitis include adenoviruses, influenza viruses, and respiratory syncytial virus (RSV). These viruses can lead to inflammation of the bronchial tubes, resulting in symptoms such as coughing, wheezing, and difficulty breathing.

While bacterial infections can occur after a viral infection or in some cases of acute bronchitis, they are not the primary cause. Allergic reactions may exacerbate respiratory symptoms but do not usually lead to acute bronchitis. Environmental irritants, such as smoke, pollution, or chemical exposure, can also contribute to the development of bronchitis; however, they are more associated with chronic bronchitis rather than its acute form. Thus, the overwhelming majority of acute bronchitis cases arise from viral infections, confirming that viral pathogens are indeed the primary catalyst for this respiratory condition.