Whooping cough is the name of an extremely contagious illness that causes a distinctive, persistent cough. The formal medical term for whooping cough is "pertussis."
Whooping cough gets its name from the cough that's one of its main symptoms. People who suffer from this bacterial infection have severe fits of coughing that cause them to make a "whoop" sound as they gasp for breath between coughs. While whooping cough is rare and easily preventable through vaccination, it can be very serious, especially for infants. Whooping cough sticks around so long that in China it's known as the "100-day cough."