Rubella Case Definition

This document contains the case definitions for rubella which is nationally notifiable within Australia. This definition should be used to determine whether a case should be notified.

Page last updated: 29 May 2019

Version Summary of changes Last reviewed Implementation date
1.0

Initial case definition

2004 2004
1.1
  • Additional detail to laboratory definitive evidence point 3 criterion and inclusion of a footnote to allow recently vaccinated cases to potentially be considered as confirmed cases
  • IgM antibody detection adjusted and moved from laboratory definitive evidence to laboratory suggestive evidence
  • Rephrasing of the probable case definition evidence requirements with no change to the actual evidence required
15 May 2019 1 July 2019

Reporting

Both confirmed cases and probable cases should be notified.

Confirmed case

A confirmed case requires laboratory definitive evidence only.

Laboratory definitive evidence

  1. Isolation of rubella virus.*

OR

  1. Detection of rubella virus by nucleic acid testing.*

OR

  1. IgG seroconversion or a significant increase in antibody level, such as a fourfold or greater rise in titre to rubella virus EXCEPT if the case has received a rubella-containing vaccine eight days to eight weeks prior to convalescent specimen collection. (NOTE: paired sera must be tested in parallel).

*Where rubella vaccine has been given in the 3 weeks prior to illness onset and wild-type virus is not detected, or unable to be detected, a case may be considered “Probable” only if the criteria for clinical and epidemiological evidence can also be met, suggesting wild-type infection. Vaccine-associated rubella illness (genotype 1A) is not notifiable, but rather should be reported as an adverse event following immunisation.

Probable case

A probable case requires:

Laboratory suggestive evidence AND clinical evidence.

OR

Clinical evidence AND epidemiological evidence.*

Laboratory suggestive evidence

  1. Detection of rubella-specific IgM antibody, EXCEPT
    1. If ruled out by more specific rubella IgM serology testing at a jurisdictional public health laboratory.

OR

    1. If the case has received a rubella-containing vaccine eight days to eight weeks before testing.

Clinical evidence

  1. A generalised maculopapular rash.

AND

  1. Fever.

AND

  1. Arthralgia/arthritis OR lymphadenopathy OR conjunctivitis.

Epidemiological evidence

An epidemiological link is established when there is:

  1. Contact between two people involving a plausible mode of transmission at a time when:
    1. one of them is likely to be infectious (about one week before to at least four days after appearance of rash).

AND

    1. the other has an illness which starts within 14 and 23 days after this contact.

AND

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

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