Pertussis Summary

Key Facts

  • Causative agent: Bordetella pertussis
  • Incubation: 7-10 days (5-21 range)
  • Infectious period: Onset until 48h antibiotics OR 21d untreated
  • Transmission: Aerosol droplets
  • Notifiable disease

Disease Phases

  • Catarrhal (1-2w): URI-like symptoms
  • Paroxysmal (1-6w): Characteristic "whoop", post-tussive vomiting
  • Convalescent (up to 3m): "100-day cough"

Diagnosis

  • Suspicion: Cough ≥14d + paroxysms/whoop/vomiting
  • PCR/NAAT: ≤4 weeks of cough (94% sensitivity)
  • Culture: ≤2 weeks (100% specific)
  • Serology: 2-12 weeks post-cough

Antibiotic Treatment

  • Infants <1m: Clarithromycin
  • Children ≥1m & adults: Clarithromycin/Azithromycin
  • Pregnant women: Erythromycin
  • Alternative: Co-trimoxazole if macrolides contraindicated

Admission Criteria

  • Age ≤6 months and acutely unwell
  • Apnoea, severe paroxysms, cyanosis
  • Significant complications (seizures, pneumonia)

Prevention

  • Exclusion: 48h antibiotics OR 21d if untreated
  • Prophylaxis: For high-risk contacts
  • Priority groups: Unvaccinated infants, pregnant women ≥32w, healthcare workers

Complications

  • Respiratory: Pneumonia, apnoea, pneumothorax
  • Neurological: Seizures, encephalopathy
  • Other: Hernias, rib fractures, hemorrhages

Pertussis (Whooping Cough)

Highly infectious disease caused by Bordetella pertussis

Introduction

Whooping cough, also known as pertussis, is a highly infectious disease caused by the bacterium Bordetella pertussis, which produces pertussis toxin and other substances which are believed to have an important pathogenic role in the disease. Whooping cough is now relatively rare compared with the pre-vaccination era.

Key Facts

  • Incubation period: 7-10 days (range 5-21 days)
  • Spread by aerosol droplets during coughing
  • Infectious period: from symptom onset until 48 hours of appropriate antibiotics OR 21 days if untreated
  • Notifiable disease

Clinical Disease

Catarrhal Phase (1-2 weeks)

  • Rarely diagnosed unless known contact
  • Similar to upper respiratory tract infection:
    • Nasal discharge
    • Conjunctivitis
    • Malaise
    • Sore throat
    • Low-grade fever
    • Dry, unproductive cough

Paroxysmal Phase (1-6 weeks)

  • Patient relatively well between coughing fits
  • Characteristic "whoop" sound (absent in adults and infants <3 months)
  • May cause cyanosis in children
  • Frequently associated with post-tussive vomiting
  • Adults may experience sweating attacks, facial flushing, cough syncope
  • More common at night
  • May be triggered by cold or noise

Convalescent Phase (up to 3 months)

  • Gradual improvement in cough frequency/severity
  • Known as "the one hundred day cough"

Note: Subsequent infections are usually less severe. Vaccination may not prevent infection but usually attenuates the disease.

Complications

Respiratory

  • Secondary bacterial bronchopneumonia
  • Secondary bacterial otitis media
  • Apnoea following coughing spasms
  • Pneumothorax

Neurological

  • Seizures
  • Encephalopathy

Other

  • Unilateral hearing loss
  • Hernias (abdominal/inguinal)
  • Rectal prolapse
  • Rib fractures
  • Subconjunctival/scleral haemorrhage
  • Facial/truncal petechiae
  • Dehydration/malnutrition from vomiting

Diagnosis

Clinical Suspicion

Suspect pertussis if acute cough lasting ≥14 days without apparent cause PLUS one or more of:

  • Paroxysmal cough
  • Inspiratory whoop
  • Post-tussive vomiting
  • Undiagnosed apnoeic attacks in infants

Higher suspicion if unvaccinated or contact with confirmed/suspected case.

Test Timing Notes
Nasopharyngeal culture ≤2 weeks of cough Specificity 100%, sensitivity 30-60%
PCR (NAAT) ≤4 weeks of cough Sensitivity 94%, recommended with culture
Serology (anti-PT IgG) 2-12 weeks post-cough >100 IU/mL suggestive (if no recent vaccination)
Oral fluid testing Children >2 years Anti-pertussis IgG in oral fluid (UK)
Other Investigations
  • FBC: Lymphocytosis common in children
  • CXR: Normal or peribronchial thickening/infiltrates

Management

Admission Criteria

  • Age ≤6 months and acutely unwell
  • Significant breathing difficulties (apnoea, severe paroxysms, cyanosis)
  • Significant complications (seizures, pneumonia)

Antibiotic Treatment

If onset within 21 days and not admitted:

Patient Group First-line Antibiotic Alternative
Infants <1 month Clarithromycin Co-trimoxazole if macrolides contraindicated
Children ≥1 month & adults Clarithromycin or Azithromycin
Pregnant women Erythromycin

Supportive Care

  • Mainstay if beyond 21 days
  • Early treatment of secondary infections

Prevention

Exclusion Advice

Exclude from school/work/healthcare until:

  • 48 hours of appropriate antibiotics completed OR
  • 21 days from onset if untreated

Those working with infants should avoid contact until criteria above met.

Antibiotic Prophylaxis

Offer to close contacts when:

  • Index case symptoms within 21 days AND
  • Contact is at increased risk of:
    • Severe complications (unvaccinated infants <1 year) OR
    • Transmitting to high-risk individuals (healthcare workers, pregnant women ≥32 weeks)

Same antibiotics as treatment (macrolides first-line, co-trimoxazole if contraindicated)

Priority Groups for Prophylaxis
  • Unvaccinated infants <1 year
  • Partially vaccinated infants (less than 3 doses of DTaP/IPV/Hib)
  • Pregnant women ≥32 weeks
  • Healthcare workers with infants/pregnant women
  • Household contacts of unvaccinated infants