Revised surveillance case definitions: Barmah Forest virus infection, Ross River virus infection, congenital rubella infection

This page contains the revised case defitions that come into effect on 1 Janury 2016.

Page last updated: 24 December 2015

This report provides the revised Surveillance case definitions approved by the Communicable Diseases Network Australia (CDNA) since 1 July 2015.

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, 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 CDNA.

These case definitions will be implemented on 1 January 2016 and supersede any previous versions.

Barmah Forest virus infection case definition

Reporting

Both confirmed cases and probable cases should be notified.

Confirmed case

A confirmed case requires laboratory definitive evidence only.

Probable case

A probable case requires laboratory suggestive evidence only.

Laboratory definitive evidence

Isolation of Barmah Forest virus

OR

Detection of Barmah Forest virus by nucleic acid testing

OR

IgG seroconversion or a significant increase in IgG antibody level (e.g. fourfold or greater rise in titre) to Barmah Forest virus.

Laboratory suggestive evidence

Detection of Barmah Forest virus IgM AND Barmah Forest virus IgG EXCEPT if Barmah Forest IgG is known to have been detected in a specimen collected greater than 3 months earlier.

Barmah Forest virus infection case definition changes

New probable category

Laboratory definitive evidence now only includes detection by PCR and demonstrated seroconversions. A single IgM will no longer be included in this category.

Laboratory suggestive evidence will require an IgM in the presence of IgG on the same specimen.

Single IgM positive results will no longer meet the confirmed or probable case definition.

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Ross River virus infection case definition

Reporting

Both confirmed cases and probable cases should be notified.

Confirmed case

A confirmed case requires laboratory definitive evidence only.

Probable case

A probable case requires laboratory suggestive evidence only.

Laboratory definitive evidence

Isolation of Ross River virus

OR

Detection of Ross River virus by nucleic acid testing

OR

IgG seroconversion or a significant increase in IgG antibody level (e.g. fourfold or greater rise in titre) to Ross River virus.

Laboratory suggestive evidence

Detection of Ross River virus IgM AND Ross River virus IgG EXCEPT if Ross River IgG is known to have been detected in a specimen collected greater than 3 months earlier.

Ross River virus infection case definition changes

New probable category

Laboratory definitive evidence now only includes detection by PCR and demonstrated seroconversions. A single IgM will no longer be included in this category.

Laboratory suggestive evidence will require an IgM in the presence of IgG on the same specimen.

Single IgM positive results will no longer meet the confirmed or probable case definition.

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Congenital rubella infection case definition

Congenital rubella infection is reported based on relevant evidence from a live or stillborn infant, miscarriage or pregnancy termination. Congenital rubella syndrome is reported as a subset of congenital rubella infection.

Reporting

Both confirmed cases and probable cases should be notified.

Confirmed case

A confirmed case requires laboratory definitive evidence (fetal)

OR

Laboratory definitive evidence (infant) AND epidemiological evidence

Laboratory definitive evidence

Fetal

Isolation or detection of rubella virus from an appropriate clinical sample (i.e. fetal blood or tissue, amniotic fluid, chorionic villus sample) by culture or nucleic acid testing

Infant

Isolation or detection of rubella virus from an appropriate clinical sample in an infant, by culture or nucleic acid testing.

OR

Detection of rubella-specific IgM antibody in the serum of the infant.

Epidemiological evidence

The mother has confirmed rubella infection during pregnancy (see definition for Rubella – non-congenital).

Probable case

A probable case requires

Epidemiological evidence (1st trimester infection)

OR

Epidemiological evidence (2nd and 3rd trimester infection) AND laboratory suggestive evidence (infant)

Laboratory suggestive evidence

Infant

High/rising rubella-specific IgG level in first year of life

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Congenital rubella syndrome case definition

Reporting

Both confirmed cases and probable cases should be reported.

Confirmed case

A confirmed case requires laboratory definitive evidence (fetal or infant), as described above AND clinical evidence

Clinical evidence

A live or stillborn infant with ANY of the following compatible defects: cataract, congenital glaucoma, congenital heart disease, hearing defect, microcephaly, pigmentary retinopathy, developmental delay, purpura, hepatosplenomegaly, meningoencephalitis, radiolucent bone disease or other defect not better explained by an alternative diagnosis.

Probable case

A probable case requires laboratory suggestive evidence (infant) OR epidemiological evidence, as described above AND clinical evidence

Clinical evidence

(as for confirmed CRS case).

Congenital rubella infection changes

Case definition has been renamed ‘Congenital Rubella Infection’, with a subcategory of ‘Congenital Rubella Syndrome’.

Laboratory definitive evidence separated into fetal and infant.

Laboratory suggestive evidence (maternal) reframed as epidemiological evidence and separated into 1st trimester versus 2nd/3rd trimester.

Laboratory evidence criteria throughout amended to be consistent with PHLN case definition.

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Salmonellosis case definition

Reporting

Only confirmed cases should be notified.

Confirmed case

A confirmed case requires laboratory definitive evidence only.

Laboratory definitive evidence

Isolation or detection of Salmonella species (excluding serotypes captured under the case definitions for typhoid and paratyphoid)

Salmonellosis changes Revised to reflect the creation of a separate case definition for paratyphoid.

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