Paediatric Acute care Guidelines PMH Emergency Department

Pertussis (Whooping Cough) is a highly infectious respiratory illness caused by Bordatella pertussis

Background

  • Despite immunisation, pertussis epidemics occur every 3-4 years
  • Neonates and young infants are at risk of apnoea
  • Antibiotic treatment does not shorten the duration of illness but reduces infectivity 
  • Cough may last for 3 months

General

Incubation Period

  • 7-20 days

Infectious Period

  • Patients are infectious from the initial catarrhal period to 3 weeks after onset of cough or after completion of antibiotic course

Immunity

  • Natural infection does not confer lifelong immunity
  • Immunity after infection or immunisation decreases after 5 years
  • The current Australian National Immunisation Schedule recommends acellular pertussis vaccine at 2, 4 & 6 months, 4 years and 10-15 years

Complications

  • Complications include pertussis pneumonia, seizures, hypoxic encephalopathy and death

Risk factors

  • Infants less than 6 months of age
  • Unimmunised patients

Assessment

  • Paroxysmal cough followed by inspiratory whoop is the classical presentation
  • Young infants may not have characteristic inspiratory whoop

History

  • Pertussis usually starts with mild coryza and low grade fever for 2-6 days (catarrhal stage) and is difficult to differentiate from viral URTI
  • Cattarhal stage develops into a dry, non productive paroxysmal cough which may be associated with cyanosis
  • The cough is often worse at night
  • Inspiratory whoop may or may not be present
  • Post-tussive vomiting is common in children
  • Infants younger than 6 months are at risk of apnoea
  • Ask for immunisation history

Examination

  • Most patients will not have clinical signs of lower respiratory tract infection
  • Conjunctival haemorrhage or facial petechiae may be present from forceful coughing
  • Assess for hypoxia
  • Young infants may be exhausted after coughing paroxysms

Investigations

  • Nasopharyngeal aspirate or pernasal swab for pertussis PCR, IgA and culture

Differential diagnoses

  • Bronchiolitis
  • Mycolasma pneumonia
  • Chlamydia pneumonia

Management

  • Patients with cyanosis or apnoea should be admitted for antibiotics and observation
  • Non-admitted patients with suspected pertussis should be isolated from child care, school and health care settings until 5 days of antibiotic therapy has been completed

Initial management

  • Oxygen for hypoxia
  • Respiratory support for apnoea – involve PICU early

Medications

  • Antibiotic therapy reduces infectivity but not duration of symptoms
  • Antibiotic treatment is not recommended if the duration of the paroxysmal cough is >21 days
Age   Standard protocol
 <6 months   Azithromycin 10mg/kg daily for 5 days
 >6 months

Azithromycin 10mg/kg (max 500mg) day 1
then 5mg/kg (max 500mg) daily for 4 days

 

  • Antibiotic prophylaxis is only necessary for high risk contacts of pertussis cases:
    • Any woman in the last month of pregnancy regardless of immunisation status
    • Close household contacts of any child <24 months age who have not received 3 doses of pertussis vaccine 

Admission criteria

  • Have a low threshold for admitting young infants <3 months with suspected pertussis for observation

Referrals and follow-up

  • All confirmed cases of pertussis must be reported to public health

Nursing

  • Routine nursing care

Isolation

  • Isolate suspected cases of pertussis
  • Droplet precautions
  • Patients are infectious until they have completed 5 days of antibiotics or >21 days of paroxysmal cough

References

PMH ED Guidelines:  Pertussis – Last Updated August 2014
The Australian Immunisation Handbook. 10th ed. Canberra: Australian Government Department of Health, 2013

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