Diagnosis: Pertussis (Whooping Cough)
This 9-year-old boy with a 4-day history of cough, fever, vomiting, and now a barking seal cough most likely has pertussis, and you should immediately start a macrolide antibiotic (azithromycin preferred) and isolate him for 5 days from the start of treatment. 1
Clinical Reasoning
The combination of paroxysmal coughing with post-tussive vomiting over 4 days strongly suggests pertussis rather than croup. 1 While the "barking seal cough" might initially suggest croup, several key features point away from this diagnosis:
Why This is Pertussis, Not Croup:
Age: Croup typically affects children 6 months to 6 years of age, and this patient is 9 years old—outside the typical croup age range 2, 3, 4
Duration: Croup symptoms usually resolve within 2 days, whereas this patient has had symptoms for 4 days with progression 4
Classic pertussis triad present: The patient has paroxysmal coughing (implied by "barking" episodes), post-tussive vomiting, and cough lasting ≥2 weeks is not required for diagnosis when these features are present 1
Guideline-based diagnosis: When a patient has cough accompanied by paroxysms and post-tussive vomiting, the diagnosis of pertussis should be made unless another diagnosis is proven 1
Immediate Management Algorithm
1. Confirm Clinical Diagnosis
- Assess for the 3 classical characteristics in children: paroxysmal cough, post-tussive vomiting, and inspiratory whooping 1
- Post-tussive vomiting in children has moderate sensitivity and specificity for pertussis (60% and 66% respectively) 1
- The presence of fever does NOT exclude pertussis in children 1
2. Obtain Diagnostic Testing
- Order a nasopharyngeal aspirate or Dacron swab for culture—this is the only certain way to make the diagnosis 1
- Culture isolation of Bordetella pertussis provides definitive confirmation 1
- PCR testing is available but not universally standardized for routine clinical use 1
3. Start Antibiotic Therapy Immediately
- Do not wait for culture results—start a macrolide antibiotic immediately 1
- Early treatment within the first few weeks will diminish coughing paroxysms and prevent disease spread 1
- Azithromycin is the preferred macrolide 5
- Isolate the patient for 5 days from the start of antibiotic treatment 1
4. Avoid Ineffective Treatments
- Do NOT use: long-acting β-agonists, antihistamines, corticosteroids, or pertussis immunoglobulin—there is no evidence these benefit pertussis patients 1
- This is critical: steroids that would be used for croup are explicitly contraindicated in pertussis 1
5. Supportive Care
- Provide frequent small feedings to prevent aspiration, as post-tussive vomiting leads to weight loss and feeding difficulties 5
- Maintain a calm, quiet environment to minimize coughing triggers 5
- Monitor for complications including pneumothorax, subconjunctival hemorrhage, and secondary bacterial pneumonia 5
Critical Pitfalls to Avoid
Do not treat this as croup with steroids and nebulized epinephrine—these are ineffective for pertussis and delay appropriate antibiotic therapy 1
Do not delay antibiotic treatment waiting for confirmatory testing—early treatment is essential for reducing symptom severity and preventing transmission 1
Do not assume the patient is not contagious after symptoms start—patients remain highly contagious until 5 days of appropriate antibiotic therapy 1
Do not forget contact tracing and prophylaxis—identify and treat close contacts, especially unvaccinated infants who are at highest risk for severe disease and death 5