Final answer:
Pertussis or whooping cough manifests as a runny nose and low-grade fever, paroxysmal cough with a 'whoop' sound, and vomiting and exhaustion after intense coughing fits, representing different stages of the disease.
Step-by-step explanation:
Pertussis, commonly known as whooping cough, is a respiratory tract infection caused by the bacterium Bordetella pertussis. The symptoms of pertussis can be divided into three stages, with the catarrhal stage being the initial and mildest phase, characterized by a runny nose, nasal congestion, sneezing, and low-grade fever. As the infection progresses, it enters the paroxysmal stage, which is the most severe phase. During this stage, individuals experience paroxysmal cough with a distinctive 'whoop' sound upon inhaling and may have episodes of vomiting and exhaustion following intense coughing fits. All manifestations mentioned in the question (a runny nose and low-grade fever, b paroxysmal cough with a whoop sound, c vomiting and exhaustion after coughing fits) are therefore associated with pertussis infection at different stages of the disease.