Patient presents with symptoms consistent with pertussis, also known as whooping cough.  The patient reports paroxysmal cough, characterized by repetitive, forceful coughing fits followed by a characteristic "whoop" sound during inspiration.  Onset of symptoms began approximately [Number] weeks ago, initially presenting as a mild upper respiratory infection with rhinorrhea, sneezing, and low-grade fever.  The cough has progressively worsened, becoming more frequent and severe, particularly at night.  Post-tussive emesis is also reported.  Physical examination reveals conjunctival injection and perioral cyanosis during coughing paroxysms.  Lung auscultation reveals clear breath sounds between paroxysms.  Differential diagnoses considered include bronchitis, respiratory syncytial virus (RSV), and influenza.  Based on the clinical presentation, including the characteristic whooping cough and paroxysmal nature, a presumptive diagnosis of pertussis is made.  Laboratory testing, including a nasopharyngeal swab for pertussis PCR, has been ordered to confirm the diagnosis.  Treatment is initiated with azithromycin to reduce the duration and severity of symptoms and to prevent transmission.  Patient education provided regarding the importance of isolation precautions, including covering coughs and sneezes, frequent handwashing, and limiting contact with others, especially infants and young children.  Follow-up appointment scheduled in [Number] weeks to assess treatment response and monitor for complications such as pneumonia or seizures.  ICD-10 code A37.0, Pertussis, is assigned.