Pertussis (Whooping Cough)

Pertussis, or whooping cough, is a highly contagious respiratory infection caused by Bordetella pertussis. The organism attaches to ciliated respiratory epithelium and releases toxins that paralyze cilia and impair the clearance of secretions. Pertussis toxin also promotes lymphocytosis and impairs chemotaxis, so the illness is toxin-mediated; coughing may continue even after the bacteria are no longer present. The incubation period is usually 7–10 days, with an approximate range of 4–21 days. Illness typically moves from a catarrhal phase with cold-like symptoms and a mild cough to a paroxysmal phase with repeated coughing fits, an inspiratory whoop, post-tussive vomiting, and exhaustion. Recovery is gradual and may take weeks to months. The classic pattern is less reliable in infants: a young infant may have little or no cough and instead develop apnea, cyanosis, gagging, or gasping. An adolescent or adult with a prolonged nonspecific cough can transmit pertussis to an unimmunized infant.