Pertussis

Introduction

• Bordatella pertussis Gram-negative bacteria causes
  Whooping Cough
• Incubation period 7-10 days
• Highly infectious (transmission rate of 75-100%)
• Epidemics every 3-4 years in Australia due to waning immunisation rates
• Always consider if cough is primary complaint
• Usually less severe if immunised
• Patients infectious just prior to and for 21 days after onset of cough (if untreated)

History

• Presents as cough, apnoea, cyanotic spells
• Post-tussive vomiting may be seen
• Classical whooping after paroxysms of coughing occur in toddler age but not infants
• 3 stages
  • Catarrhal (1-2 weeks)
    • Rhinorrhoea, conjunctivitis, malaise, low-grade fever
  • Paroxysmal (2-6 weeks or longer)
    • May cause fatigue with impaired feeding
    • Post-tussive vomiting common but often appears well in between episodes
    • Young infants may only have apnoea
  • Convalescent (1-2 weeks)
    • Cough may persist with less paroxysms

Examination

• Fever is uncommon
• Facial colour change, petechiae
• Secondary pneumonia or atelectasis on chest examination

Investigation

• NPA/Floqswab PCR to confirm (negative after 21 days or 5-7 days of antibiotics)

Differential

• Atypical pneumonia
• Viral bronchiolitis in infants
• Often only distinguishable by PCR viral testing

Complications

• Pneumonia is most common, especially in under 6mo group
• Can have pneumomediastinum, interstitial emphysema from popped alveoli
• Bronchiectasis is a rare late sequelae
• Hernias and rectal prolapse can also be seen
• Cerebral anoxia and encephalopathy in 1/10 000

Treatment

• Admit all infants <6mo with suspected pertussis due to risk of apnoea
• Older children admitted if significant apnoeic episodes, desaturations or feeding issues
• When to consider antibiotics
  • If diagnosed in catarrhal or early paroxysmal phase
  • Cough for <14 days (may reduce spread and school exclusion period)
  • Admitted or complications
• Options
  • Neonates: Azithromycin 10mg/kg PO for 5 days
  • Children: Clarithromycin liquid or azithromycin tablets

• Chemoprophylaxis of contacts
  • Close household contacts should receive course of antibiotics also
  • Contacts should have vaccination (esp. <8yo who have not received 5x DTPa vaccination)
• Boosters 
  • Recommended for pregnant women in third trimester and carers of infants <6mo/healthcare workers/childcare workers at least 2 weeks before close contact
  • Booster also recommended to those age >65 if haven’t received one in last 10 years
• Exclusion
  • Until 5 days of therapy or 21 days of cough
• Notify all cases (suspected or confirmed)

Chronic cough

• CXR, sputum examination and NPA-PCR for pertussis and other specific respiratory viruses
• Empiric treatment for pertussis often beneficial if meet previous criteria
• End-point of 2 months for referral for further testing looking at tests for CF, aspiration syndromes and GORD

Last Updated on October 27, 2021 by Andrew Crofton