Makindo Medical Notes

😷 Bordetella pertussis enters the respiratory tract after inhalation and destroys the ciliated epithelial cells of the trachea and bronchi through toxins. 🧪 If strong clinical suspicion of whooping cough, refer to microbiology for a pernasal swab for immediate processing to improve isolation rates of B. pertussis.

📖 About

• 🔊 The characteristic "whoop" is the sudden inspiration heard at the end of a bout of coughing.
• 😮 Whoops (not always heard) are caused by inspiration against a closed glottis.
• 👤 Humans are the only known reservoir for Bordetella pertussis.

💉 Vaccination

• 🛡️ Whooping cough is reduced with the DTP (Diphtheria, Tetanus, Pertussis) vaccine.
• ⚠️ The vaccine is not always fully protective → ~30% of severe infections occur in fully vaccinated siblings.
• 🤰 Maternal vaccination during pregnancy reduces risk in babies.
• 📉 Immunity wanes steadily through childhood → booster programmes are important.

🦠 Aetiology

• Caused by infection with Bordetella pertussis.
• Similar illness can be caused by Bordetella parapertussis.
• 🤧 Co-infection with RSV is common.
• Incubation period: ⏳ 1–2 weeks.
• Pathogenesis: Destroys ciliated respiratory epithelium → impaired mucus clearance.

☣️ Toxin Production

• 🧪 Pertussis toxin: ↑ host cell cAMP → disrupts protein regulation, prolongs symptoms.
• 💥 Tracheal cytotoxin: Destroys ciliated epithelial cells in trachea & bronchi.
• 🩸 Hemagglutinin: Adhesion molecule helping bacterial attachment.
• 🛑 Adenylate cyclase toxin: Suppresses host immunity, reducing bacterial clearance.

🔬 Characteristics

• Gram-negative coccobacillus.
• Strict aerobe, fastidious growth.
• Non-motile, non-capsulated.

🩺 Clinical Features

👶 Infants may present with apnoea and bouts of coughing ending in vomiting ± cyanosis. Symptoms are often worse at night or after feeds. ⚠️ Hypoxia → risk of neurological damage.

• Stage 1 (Catarrhal): 🤧 Coryza-type illness (runny nose, mild cough, malaise).
• Stage 2 (Paroxysmal): Violent bouts of coughing with/without characteristic "whoop".
• Stage 3 (Convalescent): Gradual recovery but cough may last weeks → “100 day cough.”
• Complications: 🌬️ Bronchiectasis, cyanosis, lobar collapse, CNS bleeds (rare).

🧪 Investigations

• 👃 Pernasal swab for culture on Bordet-Gengou agar.
• ⚡ PCR testing → rapid, sensitive diagnosis.

💊 Management

• 🏥 Refer infants <6 months (apnoea risk) and vulnerable patients for specialist care.
• 📢 Notify infectious diseases consultant → pertussis is a notifiable disease.
• Antibiotics: Azithromycin 500 mg daily × 3 days (or other macrolides).
• 👨‍👩‍👧 Prophylaxis: Treat unimmunised close contacts (siblings, household members).
• Critical care: Severe cases may require ventilation or ECMO support.

⚠️ Complications

• 🕰️ Prolonged cough (“100-day cough”).
• 🩸 Coughing bouts → petechiae, conjunctival haemorrhage, rare CNS bleeds.
• 💔 Cough-related injuries: hernias, lingual frenulum tears.
• ☠️ Infant mortality possible; late bronchiectasis in survivors.