Pertussis, also known as whooping cough, is an acute infection of the respiratory tract caused by the Bordetella pertussis bacterium. It initially presents with mild cold-like symptoms that progress to severe coughing fits ending in a high-pitched whoop as the person inhales. It is most contagious in the early stages when symptoms resemble a common cold. Pertussis is prevented through routine DPT immunization of infants and boosters for children up to age 5. Treatment focuses on reducing symptoms and spread through antibiotics or isolation.