Pertussis is a highly contagious acute respiratory infection caused by infection with the bacterium Bordetella pertussis, which is transmitted through inhalation of bacterial droplets following close contact with a person with pertussis or a latent infection.
After invading the respiratory tract, B. pertussis multiplies in the respiratory tract cilia and releases endotoxin, causing inflammation. As the secretions are viscous and have a barrier to drainage, the stagnant secretions continue to irritate the respiratory tract, causing a spasmodic cough and difficulty in breathing, and will continue to cough until the secretions are discharged.
Prolonged coughing can lead to varying degrees of airway obstruction, which in turn can lead to various complications such as pneumonia, pertussis encephalopathy and pneumothorax.