Whooping cough

• Whooping cough:

  • Highly contagious acute respiratory tract infection caused by Bordetella pertussis - gram negative bacteria
  • Coughing fits so severe that the child cannot inhale between coughs, resulting in a distinctive whooping sound as they forcefully draw in the air afterwards
  • Often referred to as the 100-day cough
  • Is infectious for the first 3 weeks of the illness
• Vaccinations:

  • Given to pregnant women at 20 weeks pregnant - antibodies cross placenta
  • Given to children as part of the 6-in-1 vaccine: given at 8, 12 and 16 weeks
• Risk factors:

  • More common in infants under 3 months old
  • Unvaccinated children
• Clinical features:

  1. Catarrhal phase 1-2 weeks: nasal discharge, sore throat, conjunctivitis, malaise, dry cough and mild fever
  2. Paroxysmal phase: where the classic whoop might be heard. Episodes of severe dry cough (which can be triggered by a startle) can be so prolonged (without the child being able to draw a breath) that they can become cyanotic, choking and gasping . Often post-tussive vomiting. May result in apnoea in younger infants.
  3. Convalescent phase 2 months or more: paroxysms reduce in frequency and severity
• Investigations:

  • Whooping cough is a notifiable disease
  • Culture of nasopharyngeal aspirates or nasal swabs
  • PCR of the throat or nasopharyngeal swabs
  • Serology or oral fluid testing for anti-pertussis IgG (only when the cough has been present for more than 2 weeks)
• Management:

  • Low threshold for admitting unwell children to hospital, especially if under 6 months old
  • Macrolide antibiotics are used if the onset of the cough was within 21 days - erythromycin, clarithromycin or azithromycin
  • Antibiotic treatment does not affect the clinical course of the illness but does eliminate B. pertussis from the nasopharynx so is used to reduce infectivity
  • Supportive care
  • Stay home from school until 48 hours after antibiotics have started or 21 days after symptom onset if not given antibiotics
• Prophylaxis:

  • Macrolide antibiotics should be considered for contact of an index case, particularly if the contact is:
  • Preterm or unimmunised baby
  • Unimmunised pregnant woman
  • Healthcare worker
• Complications:

  • Most serious complications and deaths occur in infants younger than 6 months - mortality rate of 3.5%
  • Secondary pneumonia
  • Apnoea and/or cerebral hypoxia - brain damage, seizures or encephalopathy
  • Recurrent vomiting - dehydration and weight loss
  • Increased thoracic pressure - prolapses, hernias, rib fractures or pneumothorax
  • Epistaxis
  • Subconjunctival haemorrhage
  • Facial and truncal petechiae