What is the treatment and prevention for pertussis (whooping cough)?

Treatment and Prevention of Pertussis

Azithromycin is the first-line antibiotic for both treatment and post-exposure prophylaxis of pertussis across all age groups, with the primary goal being eradication of Bordetella pertussis from the nasopharynx to prevent transmission rather than to shorten disease duration. 1

Antibiotic Treatment

First-Line Agent: Azithromycin

Azithromycin is preferred over other macrolides due to superior tolerability, shorter treatment duration, and significantly lower risk of infantile hypertrophic pyloric stenosis (IHPS) in young infants. 1

Age-Specific Dosing:

• Infants <6 months: 10 mg/kg/day for 5 days 1
• Infants ≥6 months and children: 10 mg/kg (maximum 500 mg) on day 1, then 5 mg/kg/day (maximum 250 mg) on days 2-5 1
• Adults: 500 mg on day 1, then 250 mg/day on days 2-5 1

Alternative Agents

• Clarithromycin: Equally effective as azithromycin for infants 1-5 months and older patients 1
• Trimethoprim-sulfamethoxazole (TMP-SMZ): For patients >2 months with macrolide contraindications 1
• Erythromycin: Should be avoided in infants <6 months due to IHPS risk; if used, dose is 40-50 mg/kg/day in children and 1-2 g/day in adults for 14 days 1, 2

Critical Timing Considerations

Start antibiotics immediately upon clinical suspicion without waiting for culture confirmation. 1

• Early treatment (catarrhal phase, first 2 weeks): Rapidly clears bacteria, decreases coughing paroxysms, and reduces complications 1
• Late treatment (paroxysmal phase, >3 weeks): Limited clinical benefit for the patient but still indicated to prevent transmission, as 80-90% of untreated patients spontaneously clear the organism within 3-4 weeks 1
• Macrolide therapy eradicates B. pertussis from the nasopharynx regardless of when treatment begins 3

Infection Control

• Isolate patients at home and away from work/school for 5 days after starting antibiotics 1
• If antibiotics cannot be administered, isolation should continue for 21 days after cough onset 3

Ineffective Therapies to Avoid

Do not use β-agonists, antihistamines, corticosteroids, or pertussis immunoglobulin—these have no proven benefit in controlling coughing paroxysms. 1

Post-Exposure Prophylaxis (PEP)

Who Should Receive PEP

All household contacts should receive PEP, regardless of age and vaccination status. 4

Priority groups for PEP include: 4

• All household contacts
• Infants <12 months (especially <4 months)
• Pregnant women in third trimester
• Healthcare workers with known exposure
• Anyone in close contact with high-risk individuals

PEP Regimen

Use the same antimicrobial agents and dosing regimens as for treatment. 1, 4

• Timing: Administer within 21 days of exposure for effectiveness 4
• Preferred agent: Azithromycin with age-appropriate dosing 4
• Goal: Eradicate B. pertussis from nasopharynx of infected persons (symptomatic or asymptomatic) 4

Important PEP Considerations

• Pertussis is highly contagious with secondary attack rates exceeding 80% among susceptible household contacts 4
• Patients are most infectious during the catarrhal stage and first 3 weeks after cough onset 4
• Antibiotic prophylaxis does not provide long-term protection; vaccination remains the most important preventive strategy 4

Prevention Through Vaccination

Pediatric Vaccination Schedule

• Primary series: Five doses of DTaP vaccine before 7 years of age 1
• Adolescent booster: Single dose of Tdap between 11-18 years 1, 5

Adult Vaccination

• All adults 19-64 years: Single dose of Tdap if not previously administered 1
• Pregnant women: Tdap between 27-36 weeks' gestation with each pregnancy to convey immunity to the newborn 1, 6

Critical Vaccination Concepts

Vaccine immunity wanes after 5-10 years, making previously vaccinated individuals susceptible to infection. 1, 4

• Neither vaccination nor natural disease provides lifelong immunity 3
• Vaccination reduces disease duration and severity by approximately 50% but does not eliminate infection risk 3
• Vaccinated individuals with breakthrough infections can still transmit disease to others 3
• "Cocooning" (vaccinating close contacts) is no longer recommended as a primary strategy because immunized patients can still contract and transmit pertussis 6

Common Pitfalls to Avoid

• Do not dismiss pertussis based solely on vaccination status—breakthrough infections occur frequently 3
• Do not assume typical "whooping" presentation—vaccinated children and adults often have atypical symptoms 3
• Do not delay testing or treatment while waiting for classic symptoms to develop 3
• Do not administer azithromycin simultaneously with aluminum- or magnesium-containing antacids as they reduce absorption 1
• Erythromycin and clarithromycin (but NOT azithromycin) inhibit cytochrome P450 and can interact with other medications 1

Diagnostic Confirmation

Obtain nasopharyngeal aspirate or Dacron swab for culture or PCR testing to confirm diagnosis. 1, 6

• PCR testing has replaced culture as the preferred confirmatory test 6
• Suspect pertussis when cough lasts ≥2 weeks with paroxysms, post-tussive vomiting, and/or inspiratory whooping, even in fully vaccinated individuals 3