Contents

Appendices

Appendix 8: Notifiable disease case definitions and laboratory tests

All diseases preventable by vaccines on the Schedule (or as part of a targeted programme) are notifiable, except for human papillomavirus (HPV), seasonal influenza, rotavirus and varicella.

Note: rotavirus infections presenting as gastroenteritis are notifiable as acute gastroenteritis.

It is a legal requirement (Health Act 1956) that health professionals notify their local medical officer of health of any notifiable disease they suspect or diagnose so that appropriate action (eg, public health prevention and control activities) can be undertaken.
The case definitions used by the medical officer of health to classify the notified case for surveillance purposes (and to assist in identifying appropriate prevention and control activities) and the laboratory tests required to confirm the diagnosis can be found in Tables A8.1 and A8.2 in this appendix. The source of the information is the Communicable Disease Control Manual 2012.36 For the most up-to-date information, refer to the online version (available on the Ministry of Health website, www.health.govt.nz).

Table A8.1: Case definitions for notifiable vaccine-preventable diseases

Disease Clinical description Under investigation Suspected case Probable case Confirmed case Not a case
Diphtheria37 Respiratory diphtheria is characterised by infection primarily involving the tonsil(s), pharynx and/or larynx, low-grade fever, with or without an asymmetrical greyish-white adherent membrane of the tonsil(s), pharynx and/or nose. In moderate to severe cases there can be marked neck swelling, resulting in a ‘bull neck’ appearance. Toxic effects can arise, including cardiac and neurological symptoms (eg, myocarditis and neuropathies). Cutaneous diphtheria is characterised by secondary infection of other skin conditions or chronic ulcers with a grey membrane. Cutaneous diphtheria can act as a reservoir of bacteria capable of causing pharyngeal disease.

Toxic sequelae in cutaneous cases are rare. Other extra-respiratory presentations have also been described, including septic arthritis, conjunctivitis, and vaginal and external auditory canal infections.
A case that has been notified, but information is not yet available to classify it as probable or confirmed.   A clinically compatible illness that is not laboratory confirmed. A clinically compatible illness that is laboratory confirmed or is epidemiologically linked to a laboratory-confirmed case. A case that has been investigated and subsequently found not to meet the case definition.
Disease Clinical description Under investigation Suspected case Probable case Confirmed case Not a case
Haemophilus influenzae type b (Hib) invasive disease Invasive disease due to Hib may manifest as bacteraemia, meningitis, epiglottitis, cellulitis, septic arthritis, pneumonia, empyema, pericarditis or osteomyelitis. A case that has been notified, but information is not yet available to classify it as probable or confirmed.   A clinically compatible illness with detection of a positive antigen test in cerebrospinal fluid (CSF), or a confident diagnosis of epiglottitis by direct vision, X-ray, or laryngoscope. A clinically compatible illness that is laboratory confirmed. A case that has been investigated and subsequently found not to meet the case definition.
Disease Clinical description Under investigation Suspected case Probable case Confirmed case Not a case
Hepatitis B (acute) The clinical manifestations of acute hepatitis B infection in adults range in severity from minimal symptoms to fulminant hepatitis (in less than 1% of cases). Adults may experience the insidious onset of fever, malaise, abdominal discomfort and anorexia with jaundice and/or elevated serum aminotransferase levels.

Acute hepatitis B infection in the first few months of life seldom causes clinical disease, and symptoms or signs are less common in children than adults.

​The acute illness, but not the carrier state, is to be notified.
A case that has been notified, but information is not yet available to classify it as probable or confirmed.   A clinically compatible illness with a positive HBsAg test (aged 12 months and older). A clinically compatible illness that is laboratory confirmed, including a positive HBsAg test in infants aged under 12 months. A case that has been investigated and subsequently found not to meet the case definition.
Disease Clinical description Under investigation Suspected case Probable case Confirmed case Not a case
Measles38 An illness characterised by all of the following:
  • generalised maculopapular rash, starting on the head and neck
  • fever (at least 38oC if measured) present at the time of rash onset
  • ​cough or coryza or conjunctivitis or Koplik’s spots present at the time of rash onset.
A case that has been notified, but information is not yet available to classify it as probable or confirmed.   A clinically compatible illness. A clinically compatible illness that is laboratory confirmed or epidemiologically linked to a confirmed case. A case that has been investigated and subsequently found not to meet the case definition.
Disease Clinical description Under investigation Suspected case Probable case Confirmed case Not a case
Meningococcal invasive disease (sepsis and/or meningitis) Meningococcal disease (caused by Neisseria meningitidis) is a serious invasive disease with an acute onset. It may start as a mild flu-like illness and rapidly progress to fulminant septicaemia and death. Cases typically experience acute fever, malaise, nausea, myalgia, arthralgia and prostration. A rash occurs in about two-thirds of cases – this may be ill-defined and macular, petechial or purpuric. More severe infection leads to shock, disseminated intra-vascular coagulation (DIC), acrocyanosis and multi-organ failure. A case that has been notified, but information is not yet available to classify it as probable or confirmed.   A clinically compatible illness. A clinically compatible illness that is laboratory confirmed. A case that has been investigated and subsequently found not to meet the case definition.
Disease Clinical description Under investigation Suspected case Probable case Confirmed case Not a case
Mumps An illness with acute onset of fever and unilateral or bilateral tenderness and swelling of the parotid or other salivary gland(s), lasting more than two days, and without other apparent cause. A case that has been notified, but information is not yet available to classify it as probable or confirmed.   A clinically compatible illness. A clinically compatible illness that is laboratory confirmed or epidemiologically linked to a confirmed case. A case that has been investigated and subsequently found not to meet the case definition.
Disease Clinical description Under investigation Suspected case Probable case Confirmed case Not a case
Pertussis A disease characterised by a cough lasting longer than two weeks, and including one or more of the following:
  • paroxysms of cough
  • cough ending in vomiting or apnoea
  • ​inspiratory whoop.
A case that has been notified, but information is not yet available to classify it as suspect, probable or confirmed. In children aged under 5 years: any paroxysmal cough with whoop, vomit or apnoea for which there is no other known cause. A clinically compatible illness with a high B. pertussis IgA test or a significant increase39 in antibody levels between paired sera at the same laboratory OR a cough lasting longer than two weeks and one or more of the following, for which there is no other known cause:
  • paroxysmal cough
  • cough ending in vomiting or apnoea
  • ​inspiratory whoop.
A clinically compatible illness that is laboratory confirmed or epidemiologically linked to a confirmed case. A case that has been investigated and subsequently found not to meet the case definition.
Disease Clinical description Under investigation Suspected case Probable case Confirmed case Not a case
Pneumococcal invasive disease40 Depending on the site of infection, the main presenting conditions are meningitis, pneumonia or septicaemia.       A clinically compatible illness that is laboratory confirmed. A case that has been investigated and subsequently found not to meet the case definition.
Disease Clinical description Under investigation Suspected case Probable case Confirmed case Not a case
Poliomyelitis A disease with no other apparent cause, characterised by:
  • acute flaccid paralysis of one or more limbs with decreased or absent deep tendon reflexes in affected limbs
  • no sensory or cognitive loss
  • ​a possible effect on bulbar muscles.
A case that has been notified, but information is not yet available to classify it as probable or confirmed.   A clinically compatible illness with epidemiological link.41 A clinically compatible illness that is laboratory confirmed. A case that has been investigated and subsequently found not to meet the case definition, including cases aged under 15 years who have been deemed to have a non-polio paralytic illness by the National Certification Committee for the Eradication of Polio.
Disease Clinical description Under investigation Suspected case Probable case Confirmed case Not a case
Rubella An illness with a generalised maculopapular rash and fever and one or more of the following:
  • arthralgia/arthritis
  • lymphadenopathy
  • ​conjunctivitis.
Rubella often presents atypically and is difficult to diagnose clinically with certainty. Up to 50% of rubella infections are subclinical. If accurate diagnosis is important, it must be laboratory confirmed.
A case that has been notified, but information is not yet available to classify it as probable or confirmed.   A clinically compatible illness. A clinically compatible illness that is laboratory confirmed or epidemiologically linked to a confirmed case. A case that has been investigated and subsequently found not to meet the case definition.
Disease Clinical description Under investigation Suspected case Probable case Confirmed case Not a case
Rubella (congenital) In general, the younger the fetus when infected, the more severe the illness. Severe cases may spontaneously abort, or have multiple manifestations in infancy; mild cases may have only a single manifestation. The most common anomalies are deafness, cataract or glaucoma, congenital heart disease, and mental retardation. In addition, infants with congenital rubella syndrome are often growth retarded and may have radiolucent bone disease, hepatosplenomegaly, thrombocytopenia and purpuric skin lesions. A case that has been notified, but information is not yet available to classify it as probable or confirmed.   A clinically compatible illness. A clinically compatible illness that is laboratory confirmed. A case that has been investigated and subsequently found not to meet the case definition.
Disease Clinical description Under investigation Suspected case Probable case Confirmed case Not a case
Tetanus Most commonly presents with gradual onset of muscular rigidity and painful spasms, starting in the jaw (lockjaw, trismus) then spreading to the neck, trunk and extremities. Tetanus may cause laryngeal spasms, respiratory failure and autonomic dysfunction (fluctuations in pulse and blood pressure), leading to death – even with modern intensive care.

In less than 20% of cases, muscle rigidity and spasms are limited to a confined area close to the site of injury.
A case that has been notified, but information is not yet available to classify it as confirmed.   Not applicable. A clinically compatible case, as diagnosed by a medical practitioner. A case that has been investigated and subsequently found not to meet the case definition.
Table A8.2: Confirmatory laboratory tests for vaccine-preventable diseases42
Disease Laboratory basis for confirmation Specimen When to take specimens
Diphtheria Isolation of toxigenic Corynebacterium diphtheriae or Corynebacterium ulcerans from a clinical specimen. Swab from area of the lesion (eg, nose, throat, or skin in case of ulcer). At presentation of illness.

Laboratories must be informed that the sample is from a suspected case of diphtheria as selective media are required.
Disease Laboratory basis for confirmation Specimen When to take specimens
Haemophilus influenzae type b (Hib) Isolation of H. influenzae type b, or detection of H. influenzae type b nucleic acid from a normally sterile site. CSF and/or blood culture or aspirate from a normally sterile site. At presentation of illness.
Disease Laboratory basis for confirmation Specimen When to take specimens
Hepatitis B (acute) At least one of the following:    
 
  • HBsAg positive in an infant aged under 12 months
Blood. At presentation of illness.
 
  • change from HBsAg negative to HBsAg positive within a 12-month period (if testing is performed at the same laboratory and the cumulative history is readily available within the laboratory information systems)
   
 
  • anti-HB core IgM reactive (unless HBsAg positive more than 6 months ago and the history is readily available in laboratory information systems)
   
 
  • ​detection of hepatitis B virus (HBV) nucleic acid.
   
Disease Laboratory basis for confirmation Specimen When to take specimens
Measles43 If the case received a vaccine containing the measles virus in the 6 weeks prior to symptom onset, the laboratory confirmation requires:44    
  • evidence of infection with a wild-type virus strain obtained through genetic characterisation.
Urine; nasopharyngeal swab/saliva swab for virus. At initial presentation of illness (note: culture of virus takes up to 35 days and viral transport medium is required).
  If the case did not receive a vaccine containing the measles virus in the 6 weeks prior to symptom onset, then laboratory confirmation requires at least one of the following:    
 
  • detection of IgM antibody specific to the virus
Blood. Single specimen taken 3–4 days after onset of rash.
 
  • IgG seroconversion or a significant rise (4-fold or greater) in antibody level for the virus between paired sera tested in parallel where the convalescent serum was collected 10–14 days after the acute serum
Blood. One specimen taken at onset of illness and a second taken at least 10–14 days later. Most useful in the first few days of illness when serology may be negative and in immune-compromised people when serology may be unreliable.
 
  • isolation of measles virus by culture
Urine; nasopharyngeal swab/saliva swab for virus. At presentation. Note: viral transport medium is required.
 
  • detection of measles virus nucleic acid.
Urine; nasopharyngeal swab/saliva swab for virus. At presentation.
Disease Laboratory basis for confirmation Specimen When to take specimens
Meningococcal invasive disease At least one of the following:    
 
  • isolation of Neisseria meningitidis bacteria or detection of N. meningitidis from blood, CSF or other normally sterile site​
Blood, CSF, other sterile site. At presentation of illness.
 
  • detection of gram-negative intracellular diplococci in blood or CSF or skin petechiae
   
 
  • ​detection of meningococcal antigen in CSF.
   
Disease Laboratory basis for confirmation Specimen When to take specimens
Mumps If the case received a vaccine containing the mumps virus in the 6 weeks prior to symptom onset, the laboratory confirmation requires:    
 
  • evidence of infection with a wild-type virus strain obtained through genetic characterisation.45
Urine; nasopharyngeal swab/saliva swab for virus. At initial presentation of illness.
  If the case did not receive a vaccine containing the mumps virus in the 6 weeks prior to symptom onset, then laboratory confirmation requires at least one of the following:    
 
  • detection of IgM antibody specific to virus
Blood. Single specimen taken 3–4 days after onset of symptoms.
 
  • IgG seroconversion or a significant rise (4-fold or greater) in antibody level for the virus between paired sera tested in parallel where the convalescent serum was collected 10–14 days after the acute serum
Blood. One specimen taken at onset of illness and a second taken at least 10–14 days later.
 
  • isolation of mumps virus by culture
Saliva or viral swab taken from mouth or throat, CSF or urine. At presentation. Note: viral transport medium is required.
 
  • detection of mumps virus nucleic acid.
Saliva or viral swab taken from mouth or throat, CSF or urine. At presentation.
Disease Laboratory basis for confirmation Specimen When to take specimens
Pertussis Isolation of Bordetella pertussis or detection of B. pertussis nucleic acid, preferably from a nasopharyngeal swab.46 Nasopharyngeal swab; for PCR, ensure the correct swab is used. At initial presentation of clinically compatible illness.
Disease Laboratory basis for confirmation Specimen When to take specimens
Invasive pneumococcal disease At least one of the following:    
 
  • isolation of S. pneumoniae from blood, CSF or other normally sterile site47
Blood, CSF or other normally sterile site. On presentation to health service.
 
  • detection of S. pneumoniae nucleic acid from blood, CSF or other normally sterile site
Blood, CSF or other normally sterile site.  
 
  • a positive newer generation S. pneumoniae antigen test on CSF in individuals from whom samples were obtained after antibiotic treatment.48
Note: detection of S. pneumoniae from CSF by microscopy (ie, detection of gram-positive diplococci and/or a positive pneumococcal immunochromatographic test (PICT)) can be a useful diagnostic test, but is not sufficient for case confirmation.
CSF.  
Disease Laboratory basis for confirmation Specimen When to take specimens
Poliomyelitis Isolation of poliovirus or detection of poliovirus nucleic acid from a clinical specimen. CSF, NPS/TS, EDTA blood can be used for enterovirus PCR test. Stools are suitable for poliovirus isolation. Serum is suitable for detecting polio neutralising antibodies.

​Depending on the type of polio suspected, different types of poliovirus will need to be tested for (eg, wild poliomyelitis or vaccine-associated strains).
   
  All specimens are sent to the national poliovirus reference laboratory at ESR.49    
    Faeces. At initial presentation of illness (0–14 days after the onset of paralysis) and a second specimen collected at least 24 hours later.
    Throat swab and CSF samples may also be collected if clinically indicated. As soon as possible.
  Acute poliomyelitis titres may assist diagnosis, but viral isolation and identification are required to confirm a case of poliomyelitis. Blood. At initial presentation and 14 days later.
Disease Laboratory basis for confirmation Specimen When to take specimens
Rubella If the case received a vaccine containing the rubella virus in the 6 weeks prior to symptom onset, then laboratory confirmation requires:    
 
  • evidence of infection with a wild-type virus strain obtained through genetic characterisation.50
   
  If the case did not receive a vaccine containing the rubella virus in the 6 weeks prior to symptom onset, the laboratory confirmation requires at least one of the following:    
 
  • detection of IgM antibody specific to the virus
Blood. Four days after onset of illness.
 
  • IgG seroconversion or a significant rise (4-fold or greater) in antibody level for the virus between paired sera tested in parallel where the convalescent serum was collected 10–14 days after the acute serum
Blood. One specimen taken at onset of illness and a second taken at least 10–14 days later.
 
  • isolation of rubella virus by culture
Blood, CSF, nasopharyngeal swab. Taken within 3 days of initial presentation of illness.
 
  • detection of rubella virus nucleic acid.
Blood, CSF, nasopharyngeal swab. Taken within 3 days of initial presentation of illness. (Note: rubella virus isolation rate is poor and takes 4 weeks. Viral transport medium is required. Serology and PCR are preferred.)
Disease Laboratory basis for confirmation Specimen When to take specimens
Rubella (congenital) At least one of the following:    
 
  • demonstration of rubella-specific IgM antibody
Blood. Cord or infant blood specimen.
 
  • infant rubella antibody level that persists at a higher level and for a longer period than expected from passive transfer of maternal antibody (ie, rubella titre that does not drop at the expected rate of a 2-fold dilution per month)
Blood. One specimen at birth and second 14–21 days later.
 
  • isolation of rubella virus by culture
Throat swab. At birth. (Note: rubella virus isolation rate is poor and takes 4 weeks. Viral transport medium is required. PCR and serology are the preferred tests.)
 
  • detection of rubella virus nucleic acid.
Blood, CSF, placenta. At birth.
Disease Laboratory basis for confirmation Specimen When to take specimens
Tetanus None. Isolation of Clostridium tetani from culture of the wound site supports the diagnosis, but yield is poor, and a negative culture does not rule out tetanus. In general, laboratories have a reduced role in the diagnosis of tetanus. None.  
36Ministry of Health. 2012. Communicable Disease Control Manual 2012Wellington: Ministry of Health.
37All isolates of C. diphtheriae and C. ulcerans are notifiable until toxigenicity is determined, including cutaneous isolates. If the isolate is determined to be non-toxigenic, the case should be denotified.
38WHO is moving towards world eradication of measles, and this places a greater emphasis on laboratory confirmation of the disease. When cases of measles are clinically diagnosed, practitioners must directly notify on suspicion.
39A significant increase is generally taken as a 4-fold rise in titre. However, interpretation of serology results should be discussed with the testing laboratory or ESR.
40In the absence of invasive disease, isolation of S. pneumoniae from a non-sterile site (such as sputum, nasal aspirates and ear discharge) is not notifiable. A positive urine antigen test is also not notifiable. 
41An epidemiological link for polio is defined in the National Poliomyelitis Response Plan: www.health.govt.nz/publication/national-poliomyelitis-response-plan-new-zealand.
42The ESR lab test form (Single human source specimen form) is available at the ESR website (http://www.esr.cri.nz/health-science/test-request-forms/).
43For instructions on measles specimen collection and transport, see the National Measles Laboratory (www.measles.co.nz).
44Laboratory evidence of proven measles infection in an individual who was vaccinated with a measles-containing vaccine in the 6 weeks before symptom onset requires evidence of infection with a wild-type measles strain obtained through genetic characterisation. It is strongly recommended that, for any sporadic cases of suspected measles, 2 or more samples be taken: preferably blood for serology and nasopharyngeal swab and urine sample for PCR testing. PCR testing is not normally used in an established outbreak. Genetic characterisation should be carried out on any wild-type measles strain.
45In New Zealand, genetic characterisation is generally only performed for measles virus.
46When testing for pertussis, alternative serological tests may be available. Serology is not accepted as a confirmatory test for surveillance in the Communicable Disease Control Manual 2012. A case diagnosed from clinical findings and positive serology would be classified as ‘probable’ and not ‘confirmed’. Blood should be taken at the initial clinical presentation and a second specimen taken at least 4 days later. A positive serological test for pertussis IgA and/or IgM or rising titres would be indicative of recent infection; while serology is sometimes used, it is not a confirmatory test.
47Isolation of S. pneumoniae from a non-sterile site (such as sputum, nasal aspirates and ear discharge) is not notifiable. Note: a positive urine antigen test does not fit the definition for a positive laboratory test for the above case definition being used; a decision was made by the working group to take a pragmatic approach and only include those with a positive culture to enable serotyping and/or to include a positive CSF antigen test, as it was thought that cases of pneumococcal meningitis, especially in children, were possibly being missed.
48Occasionally, antigen test results are positive when culture results are negative.
49Address: WHO National Poliovirus Reference Laboratory, Institute of Environmental Science and Research, National Centre for Biosecurity and Infectious Disease, Wallaceville Science Centre, 66 Ward Street, Wallaceville, Upper Hutt 5018.
50In New Zealand, genetic characterisation is generally only performed for measles virus.