Final answer:
The characteristic whooping sound in pertussis is made during the paroxysmal stage, which is the most serious stage of the illness.
Step-by-step explanation:
In which stage of pertussis is the characteristic whooping sound made? The characteristic whooping sound associated with pertussis, commonly known as whooping cough, is made during the paroxysmal stage. Pertussis is a highly contagious respiratory disease caused by the bacteria Bordetella pertussis. It's during the paroxysmal stage that mucus accumulation in the lungs leads to severe, uncontrollable coughing spells. These coughing spells can be so intense that when the person inhales afterwards, the distinctive "whooping" sound is produced due to air rushing through the inflamed and restricted airways. This stage is also the most serious stage of pertussis and can last for several weeks.