Pertussis (whooping cough)

April

Full chapter update to new format. Includes changes to the following sections:

• Global epidemiology – new section
• Aotearoa New Zealand epidemiology – updated information on epidemics and high-priority groups
• At risk and priority populations – new section
• The disease – new section
• Spread of infection: Reservoir, and Infection prevention and control – new subsections
• Routine prevention – new section
• Notification and reporting: National escalation, and international reporting – new subsections
• Exposure event management – new section
• Outbreaks – new section

December

• Case definition – removal of suspected case classification; amendment of the probable case definition to allow cases that are part of an institutional outbreak or community-wide outbreak to be classified as probable if they have a clinically compatible illness, regardless of the duration of cough.
• Laboratory criteria – removal of laboratory suggestive evidence category. 
• Laboratory testing guidelines – removal of culture testing pathway; new guidance for prioritisation of testing in periods of high pertussis activity.
  • Purpose of testing, Interpretation of results, Public health service responsibilities for testing, Interpretation of test results – new subsections
• Case management – Testing no longer recommended for cases with an epidemiological link to a confirmed case.
  • Public health priority, Manaakitanga/Manaaki in practice – new subsections
• Contact management – addition of high-priority close contacts and recommendations for antibiotic prophylaxis table.
  • Public health priority, Manaakitanga/Manaaki in practice for contacts – new subsections 

October

• Management of case, Treatment – updates to recommended antibiotic therapy; removal of clarithromycin.
• Management of contacts, Prophylaxis – updates to recommended antibiotic therapy; removal of clarithromycin.
• Laboratory Testing – new section

Prior to the development of a vaccine, pertussis (whooping cough) was a significant cause of morbidity and mortality in childhood. Routine childhood immunisation against Bordetella pertussis has dramatically reduced the global incidence and mortality from pertussis, however B. pertussis continues to circulate in all countries and typically causes epidemics every 3 to 5 years. 

Refer to the Immunisation Handbook pertussis chapter (external link) for further information on the global burden of disease.

Pertussis is endemic in Aotearoa New Zealand communities. Immunity from both immunisation and infection wanes over time and this leads to epidemics occurring every 3 to 5 years. These periods of high pertussis activity typically last for 12 to 18 months before the rates return to endemic levels.

Infants aged under 12 months have the highest risk of severe illness and death, particularly those aged under 3 months where there was no vaccination in pregnancy; followed by infants who have not received 3 doses of a pertussis-containing vaccine.

Over half of infant cases are hospitalised, with hospitalisation and mortality rates higher among Māori and Pacific infants than non-Māori, non-Pacific infants. During the 2017-19 epidemic, Māori infants were hospitalised at more than twice the rate and Pacific infants at more than 4 times the rate compared to infants of New Zealand European or other ethnicity.

Refer to the Pertussis surveillance reports - ESR (external link), Pertussis dashboard - ESR (external link) and the Immunisation Handbook pertussis chapter (external link) for further information on the epidemiology of pertussis in Aotearoa New Zealand. 

• Infants aged under 3 months where there was no vaccination during pregnancy.
• Infants aged under 12 months who have received fewer than 3 doses of a pertussis-containing vaccine. 
• Māori and Pacific infants.

Infants aged under 12 months, particularly those aged 0 to 5 months, have the highest rate of pertussis notifications of any age group. Infants with pertussis are also more likely to be hospitalised due to their illness compared to older age groups. Over half of notified pertussis cases aged under 12 months require hospitalisation.

Māori and Pacific Peoples experience a disproportionately high rate of pertussis compared to non-Māori, non-Pacific. Māori and Pacific infants are also far more likely to be hospitalised than non-Māori, non-Pacific infants. These differences likely stem from inequitably low immunisation rates and differential access to healthcare.

Tāngata whaikaha | disabled people may also be a demographic group at higher risk of pertussis due to the wide-ranging inequities when accessing healthcare and poorer health outcomes compared to non-disabled people. However, the lack of data on disability in the health system makes identifying tāngata whaikaha | disabled people difficult and further evidence is needed to understand the burden of disease in this group. Consideration should be given to the needs and possible impact on any tāngata whaikaha | disabled people when making decisions about management of pertussis.

For further information on providing culturally safe and equitable care for a range of population groups, refer to the Equity chapter.

For further information on Public Health Service responsibilities under te Tiriti o Waitangi, refer to the Te Tiriti o Waitangi and Māori health chapter. 

• People with respiratory conditions.
• People with immunocompromising conditions.

The current knowledge on pertussis in groups with comorbidities is limited, but there is some evidence that people who have asthma, chronic obstructive pulmonary disease (COPD), are immunocompromised, and people who smoke are more likely to be hospitalised and/or experience severe illness [1]. 

The risk of transmitting to groups at higher risk of severe outcomes is greater for some occupational groups, especially those who work closely with those who are pregnant people and/or infants. They are therefore included as high-priority groups for follow up and consideration of antibiotic prophylaxis.

The goal of public health action for pertussis is to promote and enable antenatal and on-time childhood immunisation, and to reduce onward transmission to individuals at higher risk of severe outcomes (i.e. illness, hospitalisations and death) from pertussis, especially infants who have received fewer than 3 doses of a pertussis-containing vaccine.

Therefore, the following groups should be prioritised for follow-up in clinical and public health settings.

• Infants aged under 12 months who have received fewer than 3 doses of a pertussis-containing vaccine, especially those aged under 3 months where there was no vaccination during pregnancy and/or Māori and Pacific infants.
• During pregnancy, especially in Māori and Pacific Peoples.
• People who regularly interact with groups at higher risk of severe outcomes from pertussis (e.g. healthcare workers who regularly interact with infants aged under 12 months and/or those who are in their third trimester of pregnancy).
• People with health conditions that put them at risk of severe outcomes from pertussis (including, respiratory and/or immunocompromising conditions).

Pertussis is primarily a toxin-mediated disease. The exotoxin produced by Bordetella pertussis paralyses the cilia, and causes inflammation of the respiratory tract, which interferes with the clearing of pulmonary secretions [2] and results in the symptoms associated with pertussis.  

There are 3 stages of typical pertussis infection.

1. Catarrhal stage – rhinorrhoea and irritating mild cough (typically lasting 7 to 10 days).
2. Paroxysmal stage – paroxysms (bursts) of coughing; in children, these may end in vomiting, cyanosis or apnoea and inspiratory gasp or whoop (1 to 6 weeks). Usually afebrile.
3. Convalescent stage – less persistent cough, gradual recovery (up to 10 weeks).

Clinical presentation varies with age, immunisation status and previous infection. Infants are less likely to have the inspiratory whoop and are more likely to present with gagging, gasping, cyanosis, apnoea, or non-specific signs such as poor feeding or seizures. Adults and children partially protected by immunisation can present with illness ranging from a mild cough illness to classic pertussis.

Humans are the only reservoir for Bordetella pertussis. Adolescents, adults, and older school-age children are an important reservoir for B. pertussis and are often the source of infection for infants.

The incubation period for pertussis is usually 7 to 10 days, ranging from 5 to 21 days.

Transmission commonly occurs person-to-person through contact with droplets of respiratory, oral or nasal secretions. Indirect transmission via contaminated objects occurs rarely.

Pertussis is highly transmissible, with the rate of transmission several-fold greater than most respiratory pathogens (including influenza) such that in a non-immune population, approximately 5 to 17 secondary pertussis cases are expected from a single case (refer to the Immunisation Handbook, section 1.2.1).

Pertussis is highly infectious in the catarrhal stage and during the first 2 weeks of the paroxysmal stage of the cough. Transmissibility gradually decreases after that.

For control purposes, the infectious period lasts from the catarrhal stage to 21 days after the onset of cough. When treated with azithromycin, infectivity lasts until 2 days of antibiotics have been taken. This lengthens to 5 days if other antibiotics are used (e.g. co-trimoxazole or erythromycin).

Confirmed and probable pertussis cases in healthcare facilities should be placed in a single room with standard and droplet precautions including medical mask or N95/P2 respirator worn by staff when providing care to the case. Cohorting of patients with the same diagnosis is acceptable. Refer to Infection prevention and control guidance (external link) in healthcare settings for further information.

The optimal length of time that infectious cases should be accommodated in a single room with appropriate infection prevention and control (IPC) precautions is 5 days from the start of appropriate antibiotics, or 21 days from the start of cough. Variation in deisolation time is at the discretion of the local IPC team.

For confirmed cases of pertussis in healthcare facilities, consult immediately with IPC and/or occupational health teams to facilitate identification and management (including antibiotic prophylaxis) of close contacts including staff, current inpatients, and patients who may have been discharged to the community.

Generally, work restrictions are not necessary for asymptomatic healthcare personnel who have an exposure to pertussis and are receiving antibiotic prophylaxis. Symptomatic contacts should be stood down from their standard duties for at least 48 hours after starting treatment/antibiotic prophylaxis, and polymerase chain reaction (PCR) testing should be considered and/or arranged to confirm their diagnosis. 

Where an outbreak is identified, an outbreak management team may be convened to oversee the local control and implementation of the outbreak policy. For more information, refer to the outbreak management section.

For more information, refer to Appendix 6: Infection, prevention and control guidance.

The primary aim of routine prevention is to provide protection to high-risk individuals (infants) through antenatal immunisation and uptake of routine childhood immunisation programmes. It is important to note that acellular pertussis immunisation provides protection against severe illness in the individual but is less effective at protecting against infection or transmission to others.

Pertussis immunisation is recommended and funded from 13 weeks’ gestation (optimally from 16 weeks in the second trimester and 2 weeks prior to delivery) in every pregnancy as antibodies are able to cross the placental barrier and provide protection to the infant in their first months of life, until they are old enough to be immunised themselves.

Antenatal immunisation should be followed up with on-time childhood immunisation at 6 weeks, 3 months and 5 months. Infants are optimally protected at birth (antenatal vaccine) and once they have received all 3 doses of pertussis-containing vaccine.

Children are also eligible for booster doses of pertussis-containing vaccines at 4 and 11 years of age.

Currently, adults are eligible for pertussis-containing vaccines from 45 years (if the individual has not received 4 previous tetanus vaccine doses) and a further dose from 65 years.

There are also groups for whom immunisation is recommended but not necessarily funded, including occupational groups who routinely interact with infants and/or those who are pregnant such as people who work in healthcare services and early childhood education centres (including Kōhanga Reo and Pacific early childhood education centres).

For further information on pertussis immunisation, including information on the National Immunisation Schedule, antenatal immunisations, and recommendations (and eligibility) for occupational groups, refer to the Immunisation Handbook pertussis chapter (external link).

Confirmed: a person who has laboratory definitive evidence; OR, a person who has a clinically compatible illness  AND who has an epidemiological link to a confirmed case.

Probable: a person who has a clinically compatible illness AND either has:

• a cough lasting 14 days or more, OR
• exposure as part of an outbreak (e.g. an institutional outbreak or community-wide outbreak [when there is limited access to testing]).

Under investigation: a person who has been notified, but information is not yet available to classify further.

Not a case: a person who has been investigated and subsequently found not to meet the case definition.

A clinically compatible illness is characterised by a new onset cough without a clear alternative cause AND one or more of the following features.

• Paroxysms of coughing.
• Cough ending in vomiting.
• Inspiratory whoop.
• Apnoea or cyanosis (in infants aged under 12 months).

• An epidemiological link is established when there is: contact between 2 people at a time when 1 person is likely to be infectious (from the catarrhal stage, approximately 1 week before, to 3 weeks after onset of cough)

  AND

• the other has an illness that starts within 5 to 21 days after this contact,
  
  AND

• at least 1 case in the chain of epidemiologically linked cases (which may involve many cases) has laboratory definitive evidence of pertussis.

Laboratory definitive evidence

Detection of Bordetella pertussis nucleic acid by polymerase chain reaction (PCR) testing,

OR

Isolation of B. pertussis by culture (refer to Laboratory testing guidelines).

Refer to Appendix 4 for Direct Laboratory Notification process for pertussis

Pertussis can be difficult to distinguish clinically from other acute respiratory infections, but testing to confirm or exclude a diagnosis of pertussis in suspected cases is not always possible or necessary.

Testing of suspected cases may be carried out for the following reasons.

• To confirm or exclude a diagnosis of pertussis (noting that it is not required where someone has a clinically compatible illness and an epidemiological link to a confirmed case).
• To identify those who may spread pertussis to those who are at higher risk of severe outcomes.
• To provide insight into the dynamics of the disease and impact of interventions (to be supported by other systematic surveillance methods).
• To support local public health services in their response to pertussis cases and outbreaks.

During periods of low pertussis activity, testing is important to confirm or exclude a diagnosis of pertussis in suspected individuals. The probability of pertussis is lower during this time, therefore an accurate diagnosis is important for guiding case and contact management.

During periods of high pertussis activity, suspected cases are likely to be managed as pertussis in primary care based on clinical presentation. Testing may be prioritised to focus on confirming or excluding pertussis in those who may spread pertussis to people at higher risk of severe outcomes and to support identification of local outbreaks.

For further guidance on the groups that should continue to be tested in periods of high pertussis activity, refer to: 

Guidance for prioritisation of testing in periods of high pertussis activity [PDF, 161 KB]

Health practitioners should notify the local medical officer of health on suspicion of pertussis during the initial assessment of the person.

If pertussis is suspected, the following information should be included on the laboratory test request form.

• Symptoms.
• Symptom onset date.
• Immunisation status. 
• Any known links to another case or outbreak (testing is usually not required for cases with an epidemiological link to a confirmed case).
• If the suspected case has known contact with individuals at higher risk of severe outcomes from pertussis.

The medical officer of health or other public health service clinical staff will discuss urgent cases with the on-call clinical microbiologist for urgent polymerase chain reaction (PCR) test processing. The clinical microbiologist can ensure laboratory staff are aware of the urgency and can prioritise the sample for processing. The turnaround time for a prioritised test is 24 to 36 hours after arrival at the laboratory.

Samples from individuals with a high index of suspicion that require urgent processing should be marked ‘Urgent Public Health’.

Polymerase chain reaction (PCR) testing is the primary diagnostic tool. Laboratory confirmation requires a positive PCR result for pertussis. Refer to Laboratory criteria for laboratory definitive evidence criteria and Case classifications for confirmed and probable case definitions.

Bordetella pertussis polymerase chain reaction (PCR) 

For laboratory confirmation of B. pertussis, a nasopharyngeal sample is recommended for PCR testing in people where their cough has been present for less than 3 weeks. A positive PCR result is more likely within 10 to 14 days of symptom onset.

After 4 weeks from cough onset, the amount of bacterial DNA in the nasopharynx rapidly diminishes, increasing the risk of a false-negative result [3,4,5]. 

Serology

Most laboratories in Aotearoa New Zealand do not offer serology testing for B. pertussis.

Serology Immunoglobulin G (IgG)

The use of serology in the investigation of a suspected pertussis case is only recommended where PCR testing is not possible AND it is requested by a medical officer of health after discussion with a clinical microbiologist. This is because the sensitivity and specificity of IgG serology is low and cannot be used as a confirmatory test of infection or immunisation. The presence of B. pertussis IgG is not a reliable indicator for a person’s immune status and should not be used in this context.

Culture

Culture is not routinely performed for diagnostic purposes. Pertussis PCR testing is between 2 and 6 times more sensitive than culture and is the recommended diagnostic method.

Attending health practitioners must immediately notify their local public health service of individuals on suspicion of pertussis. Notification from health practitioners should not await laboratory confirmation.

Laboratories are also required to notify medical officers of health of positive pertussis test results.

Public health services should ensure complete case information is entered into the appropriate surveillance database for notifiable diseases (i.e. EpiSurv).

National escalation for pertussis is generally not required, except for awareness of new and/or significant outbreaks, where there is an event that will attract national media or political attention, or if other issues arise (e.g. test or antibiotic supply issues, or capacity constraints). 

Refer to Appendix 5: Escalation pathways for more information.

There are no routine international reporting requirements. If there have been exposures overseas, then reporting could occur via International Health Regulation processes.

The primary goal of public health action for pertussis is to prevent onward transmission, particularly to those at higher risk of severe outcomes of pertussis (Table 3: High-priority close contacts and recommendations for antibiotic prophylaxis).

Follow up of probable and confirmed cases and the relevant public health actions should be initiated as soon as possible, ideally within one day of notification.

It is critical that a manaaki-centred, and driven, approach underpins all response and engagement mechanisms. Through best practice and culturally appropriate manaaki (wellbeing) approaches that respond to the needs of Māori and Pacific Peoples, relationships and trust can be established and strengthened between public health services, cases and wider contacts.

As pertussis can be severe and usually requires a period of isolation, it can be a distressing time for whānau. The following approaches should be prioritised when engaging with cases and caregivers.

• Ensuring Māori and Pacific equity leadership to support decision making.
• Public health services should be aware of the burden on settings (particularly early childhood education centres) that fulfilling public health requests may involve and work to support institutional management in coordinating the response in that setting.
• Understanding and elevating the fundamental needs and priorities of whānau will help with finding the most effective and appropriate approach to engage and follow up with the case and/or their caregivers. This may include identifying a whānau member to act as a single point of contact for the household.
• Allow plenty of time to connect and communicate with the case and/or their caregivers, and to understand which of their close contacts may need to be followed up.
• Although pertussis is a vaccine-preventable disease, immunity wanes, and there are many reasons that someone may not have been immunised or received boosters (including barriers to care). Consider using this opportunity to explore the reasons that cases may not have been immunised and address any barriers or concerns.
• If the case is pregnant, it is recommended to link with their lead maternity carer to provide additional support.

For further information on providing culturally safe and equitable care for a range of population groups, refer to the Equity chapter.

For further information on Public Health Service responsibilities under te Tiriti o Waitangi, refer to Te Tiriti o Waitangi and Māori health chapter.

For further information on support that is available, refer to Appendix 7: Manaaki and Welfare.

Generally, the case will be managed by the treating clinician. The following information should be checked and recorded in the notification to the local public health service.

• Pertussis immunisation status (for infants aged under 12 months this information should include antenatal immunisation status and number of doses since birth).
• Ethnicity.
• Pregnancy status.
• Occupation (and whether they routinely interact with any of the groups at higher risk of severe outcomes from pertussis identified above, including infants aged under 12 months, or those in their third trimester of pregnancy).
• Any priority close contacts for whom antibiotic prophylaxis would be prescribed, should be considered (especially household contacts who are either infants aged under 12 months, or those in their third trimester of pregnancy).
• If the case has been provided with the information outlined in advice to case section below. (Where this information has already been provided, follow up by public health services is not required). 
• Any information on accessibility needs that may need to be considered if further follow up by public health services is required (e.g. if the case is Deaf and/or requires a translator).

Testing is not advised for cases with an epidemiological link to a confirmed case (as they are already confirmed cases) and may not be needed in outbreak situations. Refer to the Laboratory testing section for further information.

Any person awaiting a pertussis test result should be advised to stay at home and away from early childhood education centres, school, work, or other community gatherings, while they await their test results. They should also be advised to avoid contact with any high-priority individuals within the household. The treating clinician and/or public health services should discuss with the case any potential reasons that may impact their ability to follow the recommended exclusions and restrictions and provide information on support available (refer to Appendix 7: Manaaki and Welfare for nationally available support).

Infectious cases should be excluded from work, school, preschool, and childcare, and have restricted attendance at other settings, especially where there are infants, or those in their third trimester of pregnancy, until they are no longer infectious. That is, until whichever comes first:

• 21 days after the onset of cough, or
• they have completed at least 2 days of a treatment course of azithromycin, or 5 days of a different antibiotic (co-trimoxazole or erythromycin).

Cases who are healthcare workers may be excluded from returning to their standard duties for longer than the usual 2-day restriction period, following a risk assessment by their occupational health team. The risk assessment should consider the degree of exposure to high-priority close contacts (particularly infants aged under 12 months and those in their third trimester of pregnancy). Healthcare workers are recommended to wear medical masks on return-to-work until 5 days from the start of antibiotic treatment.

In hospital settings, management of infectious cases should also include airborne/droplet precaution measures and accommodation in a single room for 5 days from the start of appropriate antibiotics (even when azithromycin is prescribed), or 21 days from the start of cough (refer to Infection prevention and control section). The decision to deisolate is at the discretion of the local infection prevention control (IPC) team and will be determined by an IPC risk assessment.

When this has not already occurred in primary care, the case or relevant caregiver should be provided with the case information letter and pertussis information sheet that includes guidance on pertussis, exclusion and restriction requirements and additional  precautions that can prevent transmission to others. Ensure communication is provided in an accessible format and is culturally and/or language appropriate. All case information letters, and the pertussis information sheet (including translated and accessible formats) can be accessed here (external link).

It is important that the case understands:

• the nature of the infection and the mode of transmission
• which individuals are at higher risk of severe outcomes from pertussis and to avoid contact with infants, and those in their last trimester of pregnancy until they are no longer infectious
• the exclusion and restriction measures they are required to follow. This opportunity should be taken to check for any problems or concerns about these measures and provide information on support that is available (refer to Appendix 7: Manaaki and Welfare section).
• that protection from immunisation or infection is not lifelong and the importance of timely immunisation as per the National Immunisation Schedule (external link), and that immunisation in every pregnancy is recommended. 

Where the case is a healthcare worker in a setting where there is an occupational health team, they should inform occupational health.

The primary goal of public health action with pertussis is to protect people at higher risk of severe outcomes, especially infants who have received fewer than 3 doses of a pertussis-containing vaccine. Intensive public health follow up is not required for all contacts, but care should be taken to ensure high-priority close contacts (Table 3) are followed up for consideration of antibiotic prophylaxis, and in particular ensuring prioritisation of Māori and Pacific individuals within each of these groups. For these groups, public health action should be initiated as soon as possible, and ideally within one day of notification.

Manaaki considerations are the same for cases and close contacts, refer to the Manaakitanga/Manaaki in practice section under case management for guidance.

A close contact is defined as someone who has been in close proximity (within 2 metres) of a case for 1 hour or more, during the case’s infectious period (including household contacts or those who have stayed overnight in the same room).

Infants aged under 6 months who are exposed to an infectious case for less than 1 hour may warrant being considered a close contact due to their higher risk of severe outcomes from pertussis.

Classification (and rationale for follow up) of close contacts should consider the likelihood of the close contact having higher risk of severe outcomes, and the likelihood of the close contact spreading pertussis to those at higher risk of severe disease outcomes (Table 3). 

High-priority close contacts for public health action may be identified and managed in primary care (at the time the case is identified) or by public health services (when the case is notified). 

When this has not already occurred in primary care, on notification of a probable or confirmed case of pertussis, people meeting the close contact definition who are in a high-priority risk group should be identified and contacted for provision of health information and offered of antibiotic prophylaxis, where appropriate.

Other close contacts who are not in a high-priority risk group may not require direct follow up and health information may instead be provided to the case to share with their contacts, where appropriate. 

Close contacts should be provided the information sheet (external link) (ensuring access to accessible or appropriate language versions, as required) for guidance on seeking medical attention if symptoms develop.

Testing is not advised for close contacts unless it has a significant impact on public health management, which should take into account those at higher risk of severe outcomes from pertussis.

Quarantine is not required for close contacts unless they develop symptoms. If they become symptomatic, they should be advised to seek medical attention and avoid attending early childhood education centres, school, work or community gatherings. It is important to clearly explain that the early stage of pertussis is indistinguishable from other minor respiratory tract infections (e.g. colds) and this is when a case is most infectious.

Additional restrictions may be advised by the local medical officer of health in partnership with equity leadership, particularly where there is a significant risk of transmission to individuals at higher risk of severe outcomes from pertussis.

When this has not already been provided to contacts (either through the case, a single point of contact, or other relevant party [e.g. clinician, early childhood education centre, school]), public health services should discuss the following information with the high-priority close contact over the phone.

Provide the contact, or the relevant caregiver, with the close contact information letter and the pertussis information sheet that includes guidance on pertussis and what to do if symptoms develop.

Ensure communication is provided in an accessible format and is culturally and/or language appropriate. All contact information letters, and the pertussis information sheet (including translated and accessible formats) can be accessed here (external link)).

Raising general awareness and promoting on-time and catch-up immunisations is important. While contact tracing, advise any unimmunised or partially-immunised close contacts, especially pregnant contacts and infants aged under 12 months, to complete their immunisations as per the National Immunisation Schedule (external link).

It is important the close contact understands:

• they should self-monitor for symptoms, and seek medical advice and avoid high-risk contacts/settings if they do develop symptoms
• they are not required to quarantine unless they develop early symptoms (including a mild fever, runny nose, and non-specific cough)
• if they are not fully immunised according to the National Immunisation Schedule (external link), they should consider getting immunised.

The letter and information sheet include information about:

• pertussis - what it is, transmission, symptoms
• what to do if symptoms occur
• antibiotic prophylaxis (if prescribed)
• any exclusion and restriction advice (if symptoms develop)
• advice on minimising spread to others
• contact details for healthcare and public health services.

The primary goal of exposure event management is to minimise pertussis transmission to people at higher risk of severe outcomes from pertussis (especially infants) through promptly identifying, informing, and providing advice about antibiotic prophylaxis and exclusion or restrictions.

Exposure events are settings a case has attended during their infectious period where an exposure has occurred. These settings may be identified during the interview with the case or their caregiver and/or information provided by the notifying clinician.

The local public health service should work with the exposure setting manager or leader, alongside relevant cultural advisors as required, to inform of the exposure and confirm details including dates and times the case was in attendance.

When interacting with hāpori (community) Māori settings such as marae/kohanga, public health services should work alongside Māori leadership from within the setting for joint decision-making and guidance. If the exposure setting is a healthcare facility such as a hospital, infection prevention and control and occupational health teams will undertake management of in-patients and staff close contacts. In these situations, the local public health service, infection prevention and control and occupational health teams should liaise as required to review progress of contact tracing. Refer to the Infection prevention and control section for further information.

The public health service is responsible for identifying and investigating exposure settings to determine the risk of transmission in the setting (noting that close contacts are defined as being within 2 metres of the index case for 1 hour or more during the case’s infectious period).

Exposure events should be prioritised according to the risk posed to contacts at higher risk of severe outcomes from pertussis. Refer to Table 3: High priority close contacts and recommendations for prophylactic antibiotics.

Potential exposure settings may include early childhood education centres (ECEs) (including Kōhanga Reo and Pacific ECEs), schools, and hospital wards.

In times of high pertussis activity ECEs should continue to be prioritised for follow up over other settings, including schools. However, there may be scenarios where there is sufficient rationale to continue the prioritisation of a school setting (for example, Te Kura Kaupapa Māori or schools with significant Māori and/or Pacific students that may have regular interaction with Māori and Pacific infants at risk of severe outcomes); public health services should consider this as part of the risk assessment.

Exposures in lower risk settings may require identification of close contacts in high-priority groups, and/or the provision of information/advice.

High-priority settings are those where there is a significant risk of transmission to people at higher risk of severe outcomes from pertussis. These settings include ECEs (including Kōhanga Reo and Pacific ECEs) and certain hospital settings (for example, maternity wards and neonatal intensive care units).

Flight contact tracing (identifying and following up individual contacts) is not generally recommended, especially during periods of high pertussis activity.

Flight contact tracing can be considered in periods of low pertussis activity, in which case publication of a media statement and location of interest for a whole flight could be considered to facilitate access to chemoprophylaxis for passengers in high priority risk groups for pertussis (Table 3: High-priority close contacts and recommendations for antibiotic prophylaxis). Public messaging should advise the following. 

• Passengers in a high-priority risk group should contact Healthline (external link) or their healthcare provider to facilitate access to antibiotic prophylaxis.  
• Other passengers should be advised to self-monitor for symptoms, check they are up to date with immunisations, seek medical assessment and stay away from those at higher risk of severe outcomes if they develop symptoms within 21 days of exposure.  

All requests for locations of interest should be sent to protection.clinical@tewhatuora.govt.nz and NIS.operations@tewhatuora.govt.nz.

An outbreak of pertussis is defined as 2 or more cases which share a plausible epidemiological link (e.g. clustered in time and place such as in the same room, ward or similar confined setting where transmission is suspected to have occurred in that setting). At least one case in the outbreak should be laboratory confirmed.

By comparison, a national pertussis epidemic may be declared if there is widespread and increasing pertussis transmission across the country at levels above typical endemic activity. Indications of severity are also taken into account, including increases in hospitalisations and/or deaths. An end to a national pertussis epidemic may be declared when transmission has returned to endemic levels across the country, along with consideration of case ascertainment and reductions in severity.

Household outbreak 

Where 2 or more cases of pertussis occur in the same household or household-like setting within one incubation period of symptom onset in the initial case.  

During periods of low activity, household outbreaks should be reported for surveillance purposes. During periods of high activity, this is not required.  

Institutional outbreak 

Where 2 or more cases of pertussis occur in the same institutional setting within 1 incubation period of symptom onset in the initial case. Institutional settings can include, but are not limited to: 

• early childhood education centres (ECEs) (including Kōhanga Reo and Pacific ECEs such as Aoga Amata)
• schools
• residential care facilities 
• hospital wards
• workplaces.

During periods of low pertussis activity, follow up of close contacts is required for outbreaks in all institutional settings.

During periods of high pertussis activity, follow up of close contacts in ECEs remains a priority but schools are de-prioritised compared to other settings. There may be scenarios where there is sufficient rationale to continue the prioritisation of a school setting (e.g. Te Kura Kaupapa Māori or schools with significant Māori and/or Pacific students that may have regular interaction with Māori and Pacific infants at higher risk of severe outcomes); public health services should consider this as part of the risk assessment.

Household outbreak

The entire household should be managed following the guidance in the case management and contact management sections and should be provided letters and information sheets (external link). People usually resident in the affected household should be managed as close contacts of a case.

The index case in a household does not require additional antibiotic prophylaxis if a secondary case is identified following their initial course of antibiotics.

Institutional outbreak

A public health response may be initiated prior to receiving all test results for individuals in a suspected outbreak if: 

• there is strong epidemiological evidence of a cluster and/or 
• staff members, residents or other attendees of an institution belong to a group at higher risk of severe outcomes from pertussis. 

Public health services should work alongside institutional management to distribute health information, review cleaning, hygiene, and infection prevention and control practices and implement appropriate transmission-based precautions if caring for cases onsite. Ensure health information is provided in an accessible format and is culturally and language appropriate.

Public health services may also consider convening an incident management team (IMT) for coordinating outbreak management and whether regional or national escalation is appropriate. If the institution is of importance to Māori or Pacific Peoples, ensure the appropriate Māori or Pacific leadership is sitting within the IMT. Refer to Appendix 5: Escalation pathways.

For more information: 

Refer to the following documents for more information.

• The Nationally Coordinated Response Plan for Outbreaks of Communicable Disease (external link) for guidance on a nationally coordinated response.
• For a step-by-step guide to the basics of disease outbreak management and a reference guide to specific aspects of outbreak management refer to the ESR Guidelines for the investigation and control of disease outbreaks (external link).

1. Jenkins, V.A., Savic, M. & Kandeil, W. (2020). ‘Pertussis in high-risk groups: an overview of the past quarter century’. Hum Vaccin Immunother., 16(11), pp. 2609-17. Available at: https://pubmed.ncbi.nlm.nih.gov/32298213/ (external link) (Accessed: 28 April 2025)
2. Centers for Disease Control and Prevention (2024). Chapter 16: Pertussis, Pink Book. Available from https://www.cdc.gov/pinkbook/hcp/table-of-contents/chapter-16-pertussis.html (external link) (Accessed: 28 April 2025)

3. Knorr, L., Fox, J.D., Tilley, P.A. et al. (2006). ‘Evaluation of real-time PCR for diagnosis of Bordetella pertussis infection’. BMC Infect Dis., 6(62) Available at: https://link.springer.com/article/10.1186/1471-2334-6-62 (external link) (Accessed: 28 April 2025)

4. He, Q., Schmidt-Schläpfer, G., Just, M. et al. (1996). ‘Impact of polymerase chain reaction on clinical pertussis research: Finnish and Swiss experiences’. J Infect Dis., 174(6), pp. 1288-95. Available at: https://pubmed.ncbi.nlm.nih.gov/8940220/ (external link) (Accessed: 28 April 2025)

5. Lee, A.D., Cassiday, P.K., Pawloski, L.C. et al. (2018). ‘Clinical evaluation and validation of laboratory methods for the diagnosis of Bordetella pertussis infection: Culture, polymerase chain reaction (PCR) and anti-pertussis toxin IgG serology (IgG-PT)’. PLoS One, 13(4). Available at: https://pubmed.ncbi.nlm.nih.gov/29652945/ (external link) (Accessed: 28 April 2025)

6. Centers for Disease Control and Prevention (CDC). (n.d.). ‘Whooping Cough (Pertussis)’. Available at: https://www.cdc.gov/pertussis/index.html (external link)

7. Starship (2024). ‘Pertussis Clinical Guidelines’. Available at: https://starship.org.nz/guidelines/pertussis/ (external link) (Accessed: 28 April 2025)

8. Committee of Infectious disease (2024). ‘Redbook: 2024-2027 Report of the Commiittee on Infectious Diseases (33rd Edition). Available at: https://publications.aap.org/redbook/book/755/Red-Book-2024-2027-Report-of-the-Committee-on?autologincheck=redirected (external link) (Accessed: 28 April 2025)

9. Altunaiji, S., Kukuruzovic, R., Curtis, N., et al. (2007). ‘Antibiotics for whooping cough (pertussis)’. Cichrane Database Syst Rev. Available at: https://pubmed.ncbi.nlm.nih.gov/17636756/ (external link) (Accessed: 28 April 2025)

10. Halperin S.S., Bortolussi, R., Langley, J.M. et al. (1999).  ‘A randomized, placebo-controlled trial of erythromycin estolate chemoprophylaxis for household contacts of children with culture-positive Bordetella pertussis infection’. Pediatrics, 104(4). Available at: https://pubmed.ncbi.nlm.nih.gov/10506267/ (external link) (Accessed: 28 April 2025)

11. Dodhia, H. & Miller, E. (1998). ‘Review of the evidence for the use of erythromycin in the management of persons exposed to pertussis’. Epidemiol Infect0,. 120(2), pp. 143-9. Available at: https://pubmed.ncbi.nlm.nih.gov/9593483/ (external link) (Accessed: 28 April 2025)

12. Wirsing von König, C. (2005). ‘Use of antibiotics in the prevention and treatment of pertussis’. Pediatr Infect Dis J., 24(5 Suppl). Available at: https://pubmed.ncbi.nlm.nih.gov/15876929/ (external link) (Accessed: 28 April 2025)

We would like to acknowledge the effort, contribution and commitment of all members of the Pertussis Clinical and Technical Advisory Group who have supported this work. Refer to Pertussis CTAG membership (external link) for a full list of members.