What are the symptoms and treatment options for infant pertussis?

Infant Pertussis Symptoms and Treatment

Infant pertussis presents with distinctive symptoms including initial catarrhal symptoms that progress to paroxysmal coughing, often with apneic episodes, and requires prompt treatment with macrolide antibiotics to reduce complications and mortality.

Clinical Presentation

Initial Phase (Catarrhal Stage)

• Pertussis begins with an insidious onset of catarrhal symptoms including nasal congestion, runny nose, mild sore throat, mild dry cough, and minimal or no fever, lasting approximately 1-2 weeks 1
• Infants may present with atypical disease, initially showing apneic spells and minimal cough or other respiratory symptoms 1
• Young infants often appear deceptively well during this early phase 2

Progressive Phase (Paroxysmal Stage)

• The initially intermittent cough becomes paroxysmal, characterized by a succession of coughs without inspiration 1
• In infants, the classic "whoop" may be absent, instead presenting with 1:
  • Gasping and gagging 2
  • Eye bulging during coughing episodes 2
  • Bradycardia and cyanosis 3
  • Post-tussive vomiting 1
• Paroxysms of cough typically increase in frequency and severity as the illness progresses, usually persisting for 2-6 weeks 1
• Coughing episodes occur more frequently at night 1

Severe Manifestations in Young Infants

• Apnea with bradycardia and hypoxia are common and concerning symptoms in infants under 6 months 3
• Leukocytosis with lymphocytosis is a hallmark laboratory finding 4, 2
• Infants often appear relatively well between coughing episodes despite the severity of their condition 1

Complications

Respiratory Complications

• Primary or secondary bacterial pneumonia 1, 3
• Pneumothorax from severe coughing 1
• Respiratory failure requiring intubation 4

Neurologic Complications

• Seizures and hypoxic encephalopathy 1
• Convulsions secondary to hypoxia 3

Other Complications

• Substantial weight loss and sleep disturbance 1
• Epistaxis, subconjunctival hemorrhage, and subdural hematoma from pressure generated by severe coughing 1
• Pulmonary hypertension in severe cases 4, 2

Risk Factors for Severe Disease

• Age less than 6 months, with highest risk in those under 2 months 1
• Unvaccinated or incompletely vaccinated status 1
• Prematurity (gestational age <37 weeks) 1
• Hispanic ethnicity (observed in mortality studies) 1

Treatment

Antimicrobial Therapy

• Macrolide antibiotics are the treatment of choice for pertussis 1, 5
• Azithromycin is the preferred first-line agent for infants 5, 4
• Early administration can reduce the duration and severity of symptoms and decrease the period of communicability 1

Supportive Care

• Hospitalization is indicated for infants younger than 6 months with signs indicating pertussis 3
• Close monitoring for apneic episodes and respiratory distress 4
• Oxygen administration for hypoxia 4
• Intubation and assisted ventilation for recurrent apnea or respiratory failure 4, 2
• Inotropic/vasoactive agents for cardiogenic shock 4
• Caffeine may be used to treat apnea in infants 6

Advanced Interventions for Severe Cases

• Serial white blood cell counts to monitor disease severity 4
• Exchange blood transfusion may be considered for severe leukocytosis with lymphocytosis 4
• Extracorporeal membrane oxygenation (ECMO) in critical cases 4

Prevention

Vaccination

• Vaccination is the most effective preventive strategy against pertussis 1, 5
• DTaP vaccine is recommended at ages 2,4,6,15-18 months, and 4-6 years 1
• Starting vaccination at 6 weeks of age is recommended in high-risk areas 2
• Maternal vaccination during pregnancy (second or third trimester) provides passive immunity to newborns 6, 2

Post-exposure Prophylaxis

• Macrolide antibiotics should be administered to close contacts of pertussis patients 5
• Household contacts and caregivers should receive prophylaxis to prevent transmission to vulnerable infants 5

Clinical Pearls and Pitfalls

• Key Pitfall: Pertussis in infants may present atypically without the classic "whoop" sound, leading to delayed diagnosis 1, 3
• Warning Sign: Apneic episodes in young infants with mild cough should raise suspicion for pertussis 1, 3
• Critical Action: Treat all presumptive cases with azithromycin without waiting for confirmatory testing 4
• Monitoring: Perform serial white blood cell counts as elevated counts correlate with disease severity and mortality 4
• Caution: Steroids and nitric oxide are not recommended for treatment of infant pertussis 4