Which of the following is characteristic of pertussis?

The characteristic feature of pertussis, also known as whooping cough, is the classic "whooping" sound that occurs during severe coughing fits, along with the hallmark of a prolonged cough that can last up to 100 days. Pertussis is caused by the bacterium Bordetella pertussis and is marked by paroxysmal coughs that can lead to vomiting or exhaustion. The distinct whooping sound arises as an individual gasps for air after a fit of coughing.

The duration of the cough, often referred to as the "100 days cough," highlights the condition's tendency for prolonged illness. In young children, this can be particularly serious, leading to complications such as apnea. The characteristic symptoms help differentiate pertussis from other respiratory illnesses.