A 16-year-old female presents with a runny nose, low-grade fever, and rapid coughing with an inspiratory whooping sound. What condition should you suspect?

The symptoms described in the scenario—runny nose, low-grade fever, rapid coughing, and an inspiratory whooping sound—are characteristic of pertussis, commonly known as whooping cough. Pertussis is caused by the bacterium Bordetella pertussis and is particularly marked by severe coughing fits that can include a distinctive "whoop" sound upon inhalation after coughing episodes.

During the initial catarrhal stage of pertussis, symptoms resemble those of a common cold, which includes a runny nose and mild fever. However, as the disease progresses, the coughing fits intensify, leading to the classic whooping sound. This can be particularly concerning in adolescents and younger children, as it may lead to complications such as apnea or difficulty in breathing.

The presence of the whooping sound is a key indicator that points towards pertussis rather than other conditions. While conditions like pneumonia or tuberculosis can present with respiratory symptoms, they typically do not cause the characteristic whoop. Rubella, on the other hand, is primarily a viral illness causing fever and rash rather than significant respiratory distress. Thus, based on the presented symptoms, pertussis is the most likely condition to suspect in this case.