Caused by the Bordetella pertussis bacterium, whooping cough is an infection that causes horrible coughing fits among children. Eventually, the coughing fits become so bad that the body is unable to take in oxygen properly, causing the distinct “whooping noise”. If left untreated, life-threatening complications, such as pneumonia and convulsions, may arise.
http://www.indiancrestpeds.com/pediatrician/childs-pediatrician-can-help-prevent-pertussis-whooping-cough/