See also

Cough

Brief resolved unexplained event (BRUE)

Foreign body

Gastroesophageal reflux in infants

Key points

1. Pertussis is a notifiable disease in Australia
2. Antibiotics reduce the severity of illness and risk of transmission if prescribed within the first 14 days of paroxysmal cough or 21 days of symptoms
3. Children are no longer infectious to others after 21 days into the illness, or after treatment with antibiotics for 5 days
4. Infants ≤6 months of age are at greatest risk of severe disease and complications

Background

• Caused by the bacterium Bordetella pertussis (occasionally Bordetella parapertussis, a less severe illness; not notifiable)
• Spread by respiratory droplets
• Infants ≤6 months of age are at greatest risk of complications (apnoea, bradycardia, severe pneumonia, seizures, encephalopathy) and are most commonly infected by spread from family members
• Can occur in immunised children, but the illness is generally less severe
• Immunity wanes after 4-12 years from last pertussis vaccine dose; neither vaccination nor natural disease confer complete or lifelong protective immunity

Incubation period

Ranges from 4-21 days, usually 7-10 days

Infectious period

From onset of symptoms until the earliest of:

• 21 days after onset of symptoms,
• 14 days after onset of paroxysmal cough, or
• completion of 5 days of appropriate antibiotics

Assessment

Diagnosis is largely clinical

History

• Catarrhal phase (1-2 weeks): coryza and non-productive cough
• Paroxysmal phase (1-2 weeks): episodes of paroxysmal coughing which peak after about a week
  • Classic paroxysms of coughing with inspiratory whoop and post-tussive vomiting are more commonly seen in unvaccinated children
  • Infants may develop apnoea, bradycardia or cyanosis with coughing spasms
• Convalescent phase (2-6 weeks, may last up to 3 months): cough tapers off
  • During recovery, superimposed viral infections can trigger a recurrence of paroxysms
• Can present as a non-specific persistent cough
• Poor feeding, weight loss, sleep disturbance
• Other family members frequently have a cough (>70% of household contacts are also infected)

Examination

• Fever is uncommon
• Clinical signs usually absent

Complications

• Otitis media, pneumonia
• Rib fractures, pneumothorax, scleral haemorrhage, hernias
• Seizures, hypoxic ischaemic encephalopathy, pulmonary hypertension

Investigations

• Laboratory confirmation is not necessary for diagnosis but may be helpful for infection control
• A nasopharyngeal flocked swab for PCR is the investigation of choice (more sensitive than culture). The test is usually negative after 21 days, or 5-7 days after effective antibiotic therapy has been commenced
• Culture (nasopharyngeal aspirate or swab) is the most specific test, and susceptibility testing can be done
• Culture is recommended for:
  • catarrhal phase
  • early paroxysmal phase
  • severe cases requiring admission
  • suspected treatment failure
  • request by public health unit
• Pertussis serology is not clinically useful
• Supporting laboratory testing:
  • blood tests should not be routinely performed
  • degree of lymphocytosis correlates with severity of disease
  • thrombocytosis is common and correlates with poorer prognosis in infants
• CXR is only indicated in unwell infants <6 months old (rare risk of B pertussis pneumonia with associated pulmonary hypertension)

Management of cases

Treatment

Indications include

• diagnosis in catarrhal or early paroxysmal phase (may reduce severity)
• cough for <14 days or symptoms for <21 days (may reduce spread and school exclusion period)
• hospital admission
• severe symptoms or complications as above

Azithromycin

<6 months old: 10 mg/kg oral daily for 5 days

≥6 months old: 10 mg/kg (max 500 mg) oral daily on day 1, then 5 mg/kg (max 250 mg) daily on days 2-5

or

Clarithromycin

≥1 month old: 7.5 mg/kg (max 500 mg) oral bd for 7 days

If macrolides are contraindicated, or B pertussis is resistant to macrolides: Trimethoprim/sulfamethoxazole (8/40 mg/mL)

>2 months old: 0.5 mL/kg (max 20 mL) oral bd for 7 days

Erythromycin is not recommended due to the risk of pyloric stenosis in infants

Admission

Consider admission for:

• all infants <6 months given risk for rapid deterioration
• respiratory distress
• inability to feed
• evidence of pneumonia
• cyanosis or apnoea, with or without coughing
• seizures

Droplet precautions are required

Isolation and school/childcare exclusion

Exclude from school, childcare and from contact with others outside the home (especially infants and young children) until the earliest of

• 21 days after onset of symptoms
• 14 days after onset of paroxysmal cough
• completion of 5 days of appropriate antibiotics

Disease notification

Notify all cases (suspected or confirmed) of pertussis

• NSW: Ph: 1300 066 055, hospital notification form
• Queensland: Ph: +617 3328 9724/9728 Fax: +617 3328 9782, notification form
• SA: Ph: 1300 232 272, online or notification form
• Victoria: Ph: 1300 651 160, Fax: 1300 651 170, online or notification form
• WA: Ph: +618 9222 0255/9328 0553 (after hours) Fax: +618 9222 0254, notification form

Management of contacts

Treatment of contacts

• Antibiotic regimens are the same as for treatment of cases (see above)
• Prophylactic treatment of contacts is aimed at preventing spread to infants <6 months of age
• Untreated infants may be infectious for longer than older people
• Management of immunocompromised contacts should be made on a case-by-case basis

Close contacts are those exposed to an infectious case during the first 21 days of their illness who are:

• family and household members
• people who have stayed overnight in the same room as the case
• people who have had face-to face contact (within 1 metre) for >1 hour (shorter period for neonates)

High-risk contacts are a subset of close contacts which includes infants <6 months of age and people who may transmit pertussis to them

Treat the following household and/or high-risk contacts within 14 days of their first contact with an infectious case (or within 21 days for infants <6 months)

• Any exposed infants <6 months of age, regardless of setting
• Any exposed pregnant woman in their last month of pregnancy, regardless of setting
• Contacts of a pertussis case who may transmit to an infant <6 months of age, including:
  • all household members where there is an infant <6 months of age present
  • healthcare staff who work with infants <6 months of age or with pregnant women (eg maternity ward or newborn nursery)
  • all children and staff in a childcare that cares for infants <6 months of age

Isolation and school/childcare exclusion

Unimmunised or incompletely immunised (<3 doses) children <7 years of age must be excluded from school or childcare for 14 days from their last exposure to infection or until they have taken 5 days of appropriate antibiotics

Vaccination

• Unimmunised or partially immunised children diagnosed with pertussis should still complete the pertussis immunisation schedule
• Close contacts who are not up to date with their pertussis immunisation should be given DTPa or dTpa as soon after exposure as possible
• Adult contacts who have not had pertussis-containing vaccine in the last 10 years should be offered one

Consider consultation with local paediatric team when

• Infant ≤6 months of age
• Child has severe disease with complications (apnoea, cyanosis, pneumonia, seizures or encephalopathy)

Consider transfer when

Child has severe disease with complications requiring care above the comfort level of the local hospital

For emergency advice and paediatric or neonatal ICU transfers, call Retrieval Services

Consider discharge when

• Tolerating coughing episodes without becoming hypoxic and/or bradycardic; most infants who are admitted with pertussis continue to have coughing paroxysms after discharge
• Tolerating adequate fluid intake

Parent information

Raising Children Network -- whooping cough

HealthDirect -- whooping cough

Last updated May 2025