Contact management: For cases under 5 years of age or cases of any age who are NAT or culture confirmed, or cases reported to have close contacts who may be at high risk for pertussis, counsel contacts at risk of disease and facilitate preventive therapy.
Case and contact management is challenging for pertussis. The evidence base is limited and the epidemiological behaviour of Bordetella pertussis is not well understood. This partly explains why pertussis is a poorly controlled bacterial vaccine-preventable disease.
Begin public health follow up as soon as possible, generally within 1 working day (see Response Times in Section 9). The objective of public health follow up of pertussis cases is to prevent disease in infants <6 months of age with particular focus on exposures in household, child care and health care settings. Therefore highest priority should generally be given to cases who are nucleic acid test (NAT) or culture confirmed and:
No action is required for cases notified >21 days after the onset of paroxysmal cough (if the onset is known) or >28 days after the onset of any cough unless they are reported to be part of a cluster.
It is the responsibility of the treating doctor to treat infectious cases and consider the need for further public health action for any high risk contacts. For cases considered high public health priority (see above) contact the treating doctor or case to identify any contacts that are infants <6 months of age or people who may transmit pertussis to these infants, and advise on management of case and contacts as necessary. For other cases, an advisory letter may be sent to the treating doctor, as required.
For cases considered high public health priority, counsel their close contacts and facilitate antibiotic prophylaxis where necessary. Recommend that contacts’ immunisations be updated if appropriate.
The bacillus Bordetella pertussis (B. pertussis)
Humans are the only reservoir for B. pertussis. Adults and adolescents are often an important source of infection for infants. 
Pertussis is mainly transmitted by large droplet infection or direct contact with discharges from respiratory mucous membranes of infectious people. Indirect spread via contaminated objects occurs rarely. There is some experimental evidence which supports airborne transmission over distances greater than one metre.
Pertussis is a prolonged coughing illness with clinical manifestations that vary by age. An initial catarrhal phase is characterised by the insidious onset of runny nose, sneezing, absent or low- grade fever, and a mild occasional cough. The cough gradually becomes paroxysmal (after 1–2 weeks), and may end in vomiting, cyanosis and/or a characteristic high-pitched inspiratory ‘whoop’. Paroxysms may recur with subsequent respiratory illnesses for many months after the onset of pertussis.  Fever is generally minimal throughout the course of the illness and sub- clinical infections may occur.  Infants are less likely to have the inspiratory whoop and a significant catarrhal stage 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 vaccination can present with illness ranging from a mild cough illness to classic pertussis, though this may be without the inspiratory whoop. In adults, post-tussive vomiting (when present) is strongly suggestive of pertussis.  The most common complication is pneumonia caused either by B. pertussis infection itself, or co-infection with viral respiratory pathogens such as respiratory syncytial virus (RSV).  Encephalopathy is a rare complication. 
The incubation period ranges from 4-21 days, usually 7 to 10 days. 
Cases are infectious from the onset of catarrhal symptoms. Communicability gradually decreases and is negligible 3 weeks after onset of cough. Secondary attack rates of 80% among susceptible household contacts have been reported.  For public health purposes, a case is considered non-infectious (even if the PCR result is still positive) at whichever time is the earlier of:
Infants under 6 months of age account for the vast majority of pertussis hospitalisations and deaths; Australian data for 2009-2010 indicate a case fatality rate of less than 0.5% in infants too young to be protected by vaccine. [5, 6]
Globally, pertussis remains a major health problem despite widespread vaccination programs. In 2009, 195 000 deaths were estimated from the disease, mostly in developing countries.  In Australia, pertussis is the most common acute vaccine preventable disease with epidemics occurring approximately every 3-4 years and the timing of epidemic activity varying across jurisdictions.  It has only relatively recently been widely recognised as a common disease of older children and adults.
Apart from direct case and contact management of pertussis, the following activities are routine prevention activities at the population level.
Pertussis immunisation is recommended for all Australian children with the first dose of pertussis-containing vaccine given from 6 to 8 weeks of age , followed by doses at 4 and 6 months, a booster from 3.5-4 years of age  and a further booster at 12-17 years of age. Lower-dose dTpa vaccines suitable for use in adolescents and adults have been available since 2001. Since 2003, dTpa vaccine has been recommended for healthcare workers and people working or living with infants, including parents, grandparents, those planning pregnancy and childcare workers who have not previously had a dose of the acellular vaccine. Immunity following vaccination begins to wane after as little as 4-5 years. 
Amongst the general public, it is important to raise awareness of:
Amongst general practitioners and other clinicians, it is important to promote ongoing clinical education about pertussis that outlines appropriate diagnosis, treatment and the identification and management of contacts.
The objective of surveillance for pertussis is to monitor and analyse the epidemiology of the disease, including the impact of immunisation, and to report on findings to inform effective and efficient prevention strategies.
The objective of public health follow up of pertussis cases is to prevent disease in infants <6 months of age with particular focus on exposure in household, childcare and healthcare settings
Within 3 working days of notification, enter confirmed and probable cases onto the jurisdictional notifiable diseases database. As soon as practicable, check and enter vaccination details for cases under 5 years of age.
A confirmed case requires either:
A probable case requires clinical evidence and epidemiological evidence.
In the absence of recent vaccination:
An epidemiological link is established when there is:
Routine testing of patients is at the discretion of the treating doctor. Public health personnel should encourage testing to confirm any probable cases where contacts <6 months of age have been reported. Laboratory testing of asymptomatic contacts should be discouraged.
With increasing availability, nucleic acid testing (NAT) should be considered the diagnostic method of choice, unless the presentation is delayed until after 4 weeks from any cough onset, or more than 3 weeks after commencement of paroxysmal cough, after which time serological testing may be more useful for diagnosis.
For further information on laboratory testing refer to the Public Health Laboratory Network (PHLN) laboratory case definitions.
Begin the follow up within 1 working day of notification of high priority cases who are NAT/culture confirmed, and more likely to be in contact with infants <6 months of age. The principles for prioritising the workload among NAT/culture confirmed high priority cases are:
Active public health action (e.g. exclusion, antibiotic use) is not required for cases notified >21 days after date of onset of paroxysmal cough (if the onset is known) or >28 days after the onset of any cough - unless they are reported to be part of a cluster - as they are unlikely to be infectious.
For cases given priority as outlined above, response will usually be carried out in collaboration with the treating doctor. Public health personnel should:
For any other cases meeting the current case definition public health personnel may offer, as resources permit, to assist the treating doctor with cases when either high risk contacts or clusters are identified by the treating doctor.
Where feasible for cases given priority, investigate the possible source of exposure-contact with a confirmed or suspected case/s.
Antibiotics given early in the catarrhal stage may ameliorate the disease but may have little effect on symptoms if given later.  Importantly, antibiotics reduce the period of communicability  and should be initiated as soon as possible. If treatment starts any later than 14 days from onset of any cough, by the time 5 days of treatment are completed, the case is already close to the end of their infectious period (21 days). Treatment is the responsibility of the attending doctor. However, it should be noted that azithromycin, especially the syrup form, may be difficult and/or expensive to obtain and that specific advice may be required. For recommended treatment see the latest edition of Therapeutic Guidelines: Antibiotic.  In 2014 the recommendations were updated and are outlined in Table 1:
Table 1. Recommended antibiotic treatment and post exposure prophylaxis for pertussis by age group
Therapeutic Guidelines: Antibiotic notes there is currently no clinical evidence to recommend the use of roxithromycin for the management of pertussis. In vitro evidence indicates it is relatively ineffective. 
The case or relevant care-giver should be advised about the nature of the infection and the mode of transmission. The factsheet is useful for this purpose (see Appendices). Cases should be advised to avoid contact with infants and women in the last month of pregnancy.
Exclusion from work, school, preschool, and child care, and restricted attendance from other settings, especially where there are infants, should be recommended for cases until they are no longer infectious until:
In hospital settings, infectious cases should be managed with droplet precautions and accommodated in a single room. 
None routinely required, except in special situations (see Section 12 Case in a healthcare worker in a maternity ward or newborn nursery).
The aim of identifying contacts is to:
Direct contact with respiratory droplets from the case is likely to pose a significant risk of transmitting infection. 
In general terms, close contacts are people with face-to-face exposure (within 1 metre) to an infectious case,  for a single period of at least one hour (based on expert opinion). In the absence of evidence concerning the minimum duration of exposure required to lead to infections in neonates, a neonate exposed to an infectious case for less than one hour may warrant being considered a close contact. In addition, close contacts are usually considered to include family and household members and, in other settings, people who have stayed overnight in the same room as the case.* All close contacts or their carers should receive information about pertussis symptoms (e.g. factsheet).
In addition, a subset of close contacts are considered high-risk contacts because of the severity of disease or the likelihood of transmitting infection to those at risk of severe disease and are recommended antibiotic prophylaxis. For the purposes of this guideline, high-risk contacts are infants <6 months of age and people who may transmit pertussis to them.
In the event of exposure in the household setting, high-risk contacts include:
In any setting, close contacts of a case who are considered high-risk contacts include:
Management of immunodeficient contacts should be made on a case by case basis.
*In non-household settings, the size of the room and degree of separation of the case from others should be considered when close contacts are being identified.
Normal human immunoglobulin (NHIG) is not effective against pertussis. There is efficient transfer of protective maternal antibodies across the placenta with a half life of 6 weeks and disappearance by 4 months.  As pertussis antibodies wane over several years, there will be little humoral antibody protection for the infant unless the mother has been vaccinated or infected shortly before or during pregnancy. 
Not applicable in the management of defined contacts. However immunisation should be promoted according to NHMRC recommendations.
There is little evidence that antibiotic prophylaxis reduces secondary transmission outside of the household setting. [15, 20] The recommended antibiotics may have associated side effects (especially gastrointestinal) that reduce compliance. Therefore antibiotic prophylaxis should be limited to contacts that include infants <6months of age or people who may transmit pertussis to these infants (high-risk contacts). Antibiotic prophylaxis is only useful if given as soon as possible after first contact with an infectious index case [4, 14]. Based on the preceding statements and considering the decline in infectiousness during the infectious period, the timeline for providing antibiotic prophylaxis to high-risk contacts should be within 14 days of first contact with an infectious case and prophylaxis is recommended in the settings outlined in Table 2. Regimens for antibiotic prophylaxis are the same as for treatment of cases–See Table 1 under Section 9. Case management.
Due to lack of evidence of effectiveness from these settings, antibiotic prophylaxis is not considered valuable in other settings such as primary schools, high schools, tertiary institutions and work places. If there are prolonged or multiple chains of transmission, the benefit of antibiotic prophylaxis is likely to be minimal.  Circumstances in which further contact occurs with an index case satisfying the recommendations for antibiotic prophylaxis, should be assessed to determine the risk of severe disease in contact/s and the benefit of repeat antibiotic prophylaxis.
Use of Table 2: The table does not cover all possible scenarios; other settings or exposures of shorter duration where high-risk individuals have been exposed may warrant consideration for prophylaxis.
Presumptions and notes:
Table 2. Recommendations for the management of contacts in various settings
Child care [G] setting (sporadic case)
All children in room with <3 doses of vaccine.
Staff who have not had a pertussis-containing vaccine in last 10 years [H]
Children: exclude for 5 days while on antibiotics or 14 days (from first exposure to infectious case) if they do not take antibiotics
Staff: not excluded while taking 5 days of antibiotics or recommend exclusion for 14 days (from first exposure to infectious case) if they do not take antibiotics
Children: not excluded if they remain well
Staff: not excluded if they remain well
Child care setting with 2 or more cases in the same room within a single incubation period [I]
All children in the room regardless of vaccination status
All staff in the room regardless of vaccination status
All children in room with <3 doses of vaccine
Staff who have not had a pertussis containing vaccine in last 10 years 
Children: exclude for 5 days while on antibiotics or 14 days (from first exposure to infectious case) if they do not take antibiotics
Healthcare settings where infants <6 months or women in their last month of pregnancy are present (including neonatal unit, maternity ward) [J]
Infants <6 months exposed to the case within 1 metre for >1 hour [K]
Parents or carers of infants <6 months/women in last month of pregnancy  exposed to the case within 1 metre for >1 hour
All staff exposed within 1 metre for >1 hour in the unit who–in the next 3 weeks–are to care for neonates or women in the last month of pregnancy regardless of vaccination status
Not applicable to Infants <6 months exposed to the case within 1 metre for >1 hour [K] or parents or carers of infants <6 months/women in last month of pregnancy  exposed to the case within 1 metre for >1 hour
Staff need only be excluded (immediately) if they become symptomatic and are to be excluded whilst considered infectious. In situations in which asymptomatic staff contacts have been recommended and refused antibiotics (e.g. an outbreak) recommend exclusion or restrict from working with infants <6 months and women in the last month of pregnancy (for 14 days from first exposure to the infectious case)
Public health personnel should manage the distribution of information to contacts (usually in the form of a letter and factsheet) through the treating doctor, or if required, directly or via the case or other intermediary (e.g., director of the childcare centre, school principals, hospital infection control staff, etc.). Contacts should be advised that they are infectious as soon as they develop catarrhal symptoms and should be excluded (immediately) from child care, preschool, school, healthcare and workplace settings and seek early medical assessment.
For childcare and healthcare settings, refer to the Exclusion section of Table 2. The general principles are to recommend exclusion of unvaccinated or incompletely vaccinated contacts (as outlined in Table 2) until:
The period of exclusion for 14 days from first exposure considers the highly (but waning) infectious nature of pertussis and covers the usual length of an incubation period (7-10 days). The benefit of exclusion is to:
If parents do not follow an exclusion request despite public health personnel attempting to convince them of the need to do so, then specific jurisdictional public health legislative provisions, where they exist, may need to be applied.
In hospital settings, patients with pertussis should be in respiratory isolation until they are no longer infectious (i.e. until they have received at least 5 days of a course of an appropriate antibiotic). Ensure staff follow droplet precautions  (including wearing a surgical mask) during close contact with cases.
In this document child care refers to long day care, family day care or settings where children aged 4 years or less are in care before they start their first year of school (this can be called preschool or kindergarten in certain jurisdictions).
In addition to usual case and contact investigation, it is important to emphasise to parents and directors of childcare facilities the need to establish each child’s immunisation status, the importance of all children complying with the immunisation schedule and the need to remain alert for symptoms in their child/ren. It is also important to recommend that the facility remain alert for respiratory illness for at least an incubation period (21 days) after last contact with the infectious case and ensure appropriate management of any further cases.
In the family day care setting where one or more infants <6 months of age are being cared for, a case in the carer or a member of the carer’s family may warrant temporary closure, as exclusion of the case is generally not practicable.
Exposures in the playgroup setting need to be considered on a case by case basis. Considerations need to include:
If advice is sought from the Public Health Unit in these situations, it is important to emphasise to parents and principals/directors of these facilities the need to establish each child’s immunisation status, the importance of all children complying with the immunisation schedule and the need to remain alert for symptoms in their child/ren. It is also important to recommend that the facility remain alert for respiratory illness for at least one incubation period (21 days) after last contact with the infectious case, that the facility report cases of respiratory illness and ensure appropriate management of any further cases.
For probable or confirmed cases, consult immediately with facility management and staff from infection control or staff health to institute a management plan appropriate to the facility. This should include procedures to:
Pertussis infection early in pregnancy may provide subsequent protective antibodies to a neonate. As the timing of delivery is not predictable, a pregnant woman with pertussis onset within a month of expected delivery and her household contacts should receive antibiotic therapy  as recommended in Table 1. If the baby is born before the mother or household contacts have completed 5 days of a course of appropriate antibiotic treatment, then the baby should receive antibiotic prophylaxis.
When outbreaks of pertussis are identified, additional control measures should be considered. An outbreak is defined as two 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). An outbreak case definition of a cough illness lasting >14 days may be used to count cases, if one case has been laboratory confirmed. Depending on the people affected and nature of the setting, control strategies may also include:
If an outbreak occurs in a healthcare facility, an outbreak management team should be convened, including a senior facility manager, Public Health Unit staff if appropriate, an infection control practitioner and appropriate clinical staff.
Appendix 1 - PHU Checklist [PDF]Appendix 2 - Pertussis Investigation Form [PDF]Appendix 3 - Pertussis FactsheetAppendix 4 - Sample Letter to Parents of a Child in a Childcare Facility with Pertussis [DOCX]Appendix 5 - Fax Back Form for Preventing Pertussis in High Risk Groups [DOCX]