Whooping cough, or pertussis, is a highly contagious respiratory infection caused by the bacterium Bordetella pertussis, characterised by severe coughing fits that can lead to a distinctive "whooping" sound during inhalation. It is clinically significant due to its potential to cause severe complications, particularly in infants, such as pneumonia, seizures, and even death. Vaccination is crucial for prevention, as outbreaks can occur in under-immunised populations.