Pertussis (Whooping Cough)

Infectious Disease • Respiratory • Vaccine-Preventable

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Overview

Pertussis, commonly known as whooping cough, is a highly contagious respiratory disease caused by the bacterium Bordetella pertussis. It is characterized by severe coughing spells that can end with a "whooping" sound when the person breathes in. Pertussis is particularly dangerous for infants and can be fatal in young children.

Global Impact: Despite widespread vaccination, pertussis causes approximately 24.1 million cases and 160,700 deaths worldwide each year, with the majority occurring in developing countries and among unvaccinated infants.

Causes & Pathophysiology

Causative Agent:

Virulence Factors:

Factor Function Effect
Pertussis Toxin (PT) ADP-ribosylating toxin Lymphocytosis, enhances bacterial attachment
Filamentous Hemagglutinin (FHA) Adhesin Mediates attachment to ciliated epithelial cells
Pertactin Outer membrane protein Adhesion, evasion of immune response
Tracheal Cytotoxin Peptidoglycan fragment Ciliary paralysis, epithelial damage
Adenylate Cyclase Toxin Increases cAMP Impairs phagocyte function

Pathophysiology:

Bacterial inhalation → attachment to ciliated respiratory epithelium → local multiplication → toxin production → ciliary paralysis and epithelial damage → inflammatory response → impaired mucus clearance → paroxysmal coughing → central nervous system effects.

Transmission:

Symptoms & Presentation

Classic Three Stages:

Stage Duration Symptoms
Catarrhal Stage 1-2 weeks Rhinitis, mild cough, low-grade fever (resembles common cold)
Paroxysmal Stage 2-6 weeks Paroxysmal coughing, whoop, post-tussive vomiting, cyanosis
Convalescent Stage Weeks to months Gradual decrease in cough frequency and severity

Characteristic Symptoms:

Atypical Presentations:

Risk Factors

High-Risk Groups:

Epidemiological Risk Factors:

  • Outbreaks typically occur every 3-5 years
  • Waning immunity in adolescents and adults
  • Areas with low vaccination coverage
  • Crowded living conditions
  • Seasonal variation (late summer and fall peaks)

Diagnosis & Investigations

Clinical Diagnosis:

Based on characteristic cough illness: cough lasting ≥2 weeks with paroxysms, whoop, or post-tussive vomiting.

Laboratory Confirmation:

Test Timing Sensitivity Notes
PCR First 3-4 weeks High Preferred method, rapid results
Culture First 2 weeks High early, decreases over time Gold standard, requires special media
Serology (IgA/IgG) After 2 weeks Variable Useful for late diagnosis, affected by vaccination
DFA First 3-4 weeks Moderate Rapid but less sensitive than PCR

Supportive Laboratory Findings:

  • Lymphocytosis: Absolute lymph count >10,000/mm³
  • Elevated white blood cell count with lymphocyte predominance
  • Chest X-ray: May show peribronchial thickening, atelectasis

Management & Treatment

Antibiotic Therapy:

Antibiotic Dosage Duration Notes
Azithromycin 10 mg/kg day 1, then 5 mg/kg days 2-5 (max 500 mg) 5 days First-line, preferred for infants
Clarithromycin 15 mg/kg/day divided BID (max 1 g/day) 7 days Alternative first-line
Erythromycin 40-50 mg/kg/day divided QID (max 2 g/day) 14 days Higher side effect profile
Trimethoprim-Sulfamethoxazole 8/40 mg/kg/day divided BID 14 days For macrolide allergy or resistance

Supportive Care:

  • Hospitalization for infants <6 months and severe cases
  • Respiratory support (oxygen, ventilation if needed)
  • Nutritional support (small, frequent feeds)
  • Hydration maintenance
  • Management of complications

Postexposure Prophylaxis:

Recommended for all household contacts and close contacts regardless of age or vaccination status. Same antibiotics and dosages as treatment.

Important: Antibiotics do not alter the clinical course if started in the paroxysmal stage but are still recommended to reduce transmission. Cough suppressants are generally not effective and not recommended.

Ayurvedic Treatment

Supportive Therapies:

  • Sitopaladi Churna: With honey for cough (children >1 year)
  • Talisadi Churna: For respiratory symptoms and fever
  • Vasa (Adhatoda vasica): Natural expectorant and bronchodilator
  • Tulsi (Holy Basil): Antimicrobial and immunomodulatory
  • Ginger and Honey: Soothing for throat irritation

Ayurvedic Procedures:

  • Steam inhalation with eucalyptus or mint
  • Warm oil massage for relaxation
  • Nasya (nasal administration of medicated oils)
  • Proper hydration with warm herbal teas
Important: Pertussis requires antibiotic treatment and can be life-threatening, especially in infants. Ayurvedic treatments should only complement conventional medical care under proper supervision.

Diet, Lifestyle & Self-care

Nutritional Support:

  • Small, frequent meals to prevent vomiting
  • Soft, easily digestible foods
  • Warm fluids (soups, broths, herbal teas)
  • Honey (for children >1 year) to soothe throat
  • Avoid foods that may trigger coughing (dry, crumbly foods)

Home Care Measures:

  • Humidified air to soothe airways
  • Adequate rest and sleep
  • Proper hydration
  • Isolation to prevent spread
  • Hand hygiene and respiratory etiquette
  • Monitoring for complications

Infection Control:

  • Isolation until 5 days after starting antibiotics
  • Without antibiotics, isolate for 21 days from cough onset
  • Contact tracing and prophylaxis
  • Environmental cleaning
  • Education of household members

Prognosis

With appropriate treatment and supportive care, most patients recover completely, though the cough may persist for weeks to months. Infants <6 months have the highest risk of severe complications and mortality.

Typical Duration:

  • Catarrhal stage: 1-2 weeks
  • Paroxysmal stage: 2-6 weeks (may be longer)
  • Convalescent stage: Weeks to months
  • Total illness duration: 6-10 weeks (often called "100-day cough")

Potential Complications:

Complication Frequency Risk Groups
Pneumonia 20% of cases Infants, elderly
Apnea 50% of infants <6 months Infants
Seizures 2% Infants
Encephalopathy 0.3% Infants
Weight loss Common All ages
Rib fractures Rare Elderly
Death 1% of infants <2 months Infants

When to Seek Medical Care

Seek immediate medical attention if:
  • Infant <6 months with cough or breathing difficulties
  • Difficulty breathing or shortness of breath
  • Blue or purple color around lips, face, or nails
  • Vomiting preventing adequate fluid intake
  • Signs of dehydration (dry mouth, no tears, decreased urination)
  • High fever (>38.5°C/101.3°F)
  • Seizures or loss of consciousness
  • Severe exhaustion or lethargy
  • Cough lasting more than 2 weeks

Prevention & Screening

Vaccination (Primary Prevention):

Vaccine Schedule Population
DTaP 2, 4, 6, 15-18 months, 4-6 years Children <7 years
Tdap 11-12 years, then Td every 10 years Adolescents and adults
Tdap During each pregnancy (27-36 weeks) Pregnant women

Cocooning Strategy:

Vaccination of close contacts of infants (parents, grandparents, caregivers) to create a protective "cocoon" around vulnerable infants.

Public Health Measures:

  • Case reporting to public health authorities
  • Contact tracing and prophylaxis
  • Outbreak investigation and control
  • Vaccination coverage monitoring
  • Public education about pertussis recognition and prevention

Screening:

Routine screening for pertussis in asymptomatic individuals is not recommended. Testing should be reserved for symptomatic individuals and their contacts.