Revised surveillance case definitions: Diphtheria; varicella-zoster infection (not elsewhere classified)

These case definitions should be used when determiningnwhether a case should be notified to the relevant health authority. These definitions came into effect from 1 January 2017

Page last updated: 30 March 2017

This report provides the revised surveillance case definitions approved by the Communicable Diseases Network Australia (CDNA) since 1 July 2016.


The Case Definitions Working Group (CDWG) is a subcommittee of the CDNA and comprises members representing all states and territories, the Australian Government Department of Health, the Public Health Laboratory Network (PHLN), OzFoodNet, the Kirby Institute, the National Centre for Immunisation Research and Surveillance and other communicable disease experts. CDWG develops and revises surveillance case definitions for all diseases reported to the National Notifiable Diseases Surveillance System. Surveillance case definitions incorporate laboratory, clinical and epidemiological elements as appropriate.


The following case definitions have been reviewed by CDWG and endorsed by PHLN and CDNA.


These case definitions were implemented on 1 January 2017 and supersede any previous versions.


Diphtheria case definition


Reporting


Both confirmed cases and probable cases should be notified.


Confirmed case


A confirmed case requires laboratory definitive evidence and clinical evidence.


Laboratory definitive evidence


Isolation of toxigenic* Corynebacterium diphtheriae or toxigenic* C. ulcerans from site of clinical evidence.


Clinical evidence – confirmed case


Upper respiratory tract infection


OR


Skin lesion


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Probable case


A probable case requires:


Laboratory suggestive evidence AND clinical evidence


OR


Clinical evidence AND epidemiological evidence.


Laboratory suggestive evidence


Isolation of C. diphtheriae or C. ulcerans from a respiratory tract specimen (toxin production unknown).


Clinical evidence – probable case


Upper respiratory tract infection with an adherent membrane of the nose, pharynx, tonsils or larynx


Epidemiological evidence


An epidemiological link is established when there is:


Contact between two people involving a plausible mode of transmission at a time when:


  • one of them is likely to be infectious (usually 2 weeks or less and seldom more than 4 weeks after onset of symptoms)


AND


  • the other has an illness which starts within approximately 2-5 days after this contact


AND


At least one case in the chain of epidemiologically linked cases (which may involve many cases) is laboratory confirmed.


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* as indicated by detection of toxin gene by nucleic acid testing


Summary of changes to diphtheria surveillance case definition Confirmed case

Laboratory definitive evidence

Added 'from site of clinical evidence'

Clinical evidence – confirmed case

Changed to 'Clinical evidence - confirmed case

Replaced 'Pharyngitis and/or laryngitis (with or without a membrane)

OR

Toxic (cardiac or neurological) symptoms'

With

'Upper respiratory tract infection

OR

Skin lesion'

Laboratory suggestive evidence

Added 'from a respiratory tract specimen (toxin production unknown).'

Added

Clinical evidence – probable case

Upper respiratory tract infection with an adherent membrane of the nose, pharynx, tonsils or larynx

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Varicella-zoster infection (not elsewhere classified) case definition


Reporting


Only confirmed cases should be notified.


Confirmed case


A confirmed case requires laboratory definitive evidence, either in the absence of clinical


Information or where clinical evidence does not meet criteria for varicella-zoster infection (chickenpox) or varicella-zoster infection (shingles).


Laboratory definitive evidence


Isolation of varicella-zoster virus.


OR


Detection of varicella-zoster virus by nucleic acid testing.


OR


Detection of varicella-zoster virus antigen by direct fluorescent antibody testing.


OR


Detection of varicella-zoster virus-specific IgM in an unvaccinated person.

Summary of changes to varicella zoster infection (not elsewhere classified) surveillance case definition Name change: changed unspecified to not elsewhere classified.

Removal of wording 'from a skin or lesion swab' from relevant criteria to broaden the types of laboratory specimen that can be tested

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