How should a 2‑month‑old infant with a pertussis‑type (paroxysmal, whooping) cough be evaluated and managed?

Management of Pertussoid Cough in a 2-Month-Old Infant

A 2-month-old infant with pertussis-type cough requires immediate hospitalization with continuous cardiorespiratory monitoring and empiric azithromycin therapy started without waiting for laboratory confirmation. 1

Immediate Actions

Hospitalization and Monitoring

• Admit all infants under 12 months with suspected pertussis for inpatient monitoring, as this age group faces the highest risk of life-threatening complications including apneic spells, bradycardia, cyanosis, and death. 1, 2
• Initiate continuous pulse oximetry and apnea monitoring immediately, as infants can present with apneic spells and minimal cough initially rather than classic paroxysmal symptoms. 1, 3
• Monitor respiratory status between paroxysms, recognizing that infants typically appear deceptively well between episodes despite severe underlying disease. 1

Empiric Antibiotic Therapy

• Start azithromycin immediately upon clinical suspicion without awaiting laboratory confirmation. 1, 4, 5
• Erythromycin (40-50 mg/kg per day) for 14 days is the FDA-approved alternative, effective in eliminating Bordetella pertussis from the nasopharynx and preventing transmission. 1, 5
• Early treatment within the first two weeks of the catarrhal phase reduces severity of subsequent cough paroxysms and lowers complication risk, though antibiotics started after the paroxysmal stage begins will not significantly alter the clinical course. 1, 6

Clinical Assessment

Recognize the Clinical Pattern

• Look for paroxysmal cough (sensitivity 93.2%) as the hallmark feature, though the classic inspiratory "whoop" may be absent in young infants. 7, 4
• Assess for post-tussive vomiting (specificity 77.7%), which strongly suggests pertussis when present. 4, 8
• In infants under 2 months, cough or choking associated with cyanosis plus rhonchi on examination indicates high likelihood of pertussis. 3
• Do not be reassured by normal appearance between episodes—this is characteristic of pertussis and does not indicate mild disease. 1

Diagnostic Confirmation

• Obtain nasopharyngeal aspirate or Dacron swab for PCR testing (preferred) or culture (100% specific). 1, 4
• Culture remains the only definitive diagnostic method, though PCR is faster and more practical. 1, 4
• Never delay treatment while awaiting laboratory results—postponement increases complications and disease spread. 1, 4

Supportive Care

Nutritional Management

• Provide frequent small feedings immediately after coughing episodes when the infant is less likely to cough, as post-tussive vomiting leads to substantial weight loss. 1
• Consider nasogastric or intravenous hydration if vomiting causes dehydration or significant weight loss. 1

Environmental Modifications

• Maintain a calm, quiet environment to minimize coughing triggers, as paroxysms can be precipitated by stimulation and occur more frequently at night. 1
• Reduce environmental irritants and tobacco smoke exposure. 1
• Ensure adequate humidification of inspired air. 1

Complication Surveillance

Monitor for Life-Threatening Complications

• Watch closely for apneic spells, which are the most dangerous complication in this age group and can occur with minimal warning. 1, 2
• Assess for secondary bacterial pneumonia or otitis media. 1
• Monitor for neurologic complications including seizures and hypoxic encephalopathy. 1
• Observe for complications from severe coughing pressure: pneumothorax, subconjunctival hemorrhage, and subdural hematoma. 1

Expect Prolonged Course

• Anticipate that the paroxysmal stage typically lasts 2-6 weeks with significant sleep disturbance, as paroxysms occur more frequently at night. 1
• Do not discharge prematurely based on appearance between paroxysms—complications can occur throughout the entire paroxysmal phase. 1

Infection Control

Isolation and Contact Management

• Isolate the infant for 5 days after initiating appropriate antibiotic therapy. 1, 4
• Identify and provide macrolide prophylaxis to all close contacts, particularly other infants and household members, to prevent secondary cases. 1

Common Pitfalls to Avoid

• Never dismiss pertussis because the infant lacks the classic "whoop"—young infants frequently present atypically with apnea and minimal cough. 4, 3
• Do not wait for laboratory confirmation before starting antibiotics—this delays critical treatment and increases transmission risk. 1, 4
• Avoid assuming improvement based on normal appearance between paroxysms—this is characteristic of the disease pattern. 1
• Do not underestimate the duration of illness—plan for 2-6 weeks of paroxysmal cough with potential for months of residual symptoms. 1, 4