Pertussis is also known as whooping cough. It is an illness of your windpipe or breathing tube and airways. Your windpipe is between your chest and throat and lets air move in and out of your lungs. Germs attach to the small hairs inside your windpipe. Then your airway swells and is sore. This leads to a bad cough. Pertussis is known to cause very bad coughing spells. The coughing spells can sometimes end in a "whoop" sound. All people with this illness will make this sound when they cough. Pertussis tends to be worse in babies and children because their airways or breathing tubes are smaller.