Whooping cough, or pertussis, is a highly contagious bacterial infection of the respiratory system. It is caused by the bacterium Bordetella pertussis, which releases toxins that damage and irritate the inner lining of the airways. The hallmark of whooping cough is a severe, spasmodic cough often followed by a distinctive ‘whoop’ sound during inhalation as the patient tries to catch their breath. While this whooping sound is most commonly heard in children, the infection can affect individuals of all ages, including teenagers, adults, and seniors.