Measles case definition

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

Page last updated: 12 March 2004

Australian national notifiable diseases case definitions - Measles

Reporting

Both confirmed cases and probable cases should be notified.

Confirmed case

A confirmed case requires either:

1. laboratory definitive evidence

OR

2. clinical evidence AND epidemiological evidence.

Laboratory definitive evidence

At least one of the following:

1. Isolation of measles virus

OR

2. Detection of measles virus by nucleic acid testing

OR

3. Detection of measles virus antigen

OR

4. IgG seroconversion or a significant increase in antibody level or a fourfold or greater rise in titre to measles virus EXCEPT if the case has received a measles-containing vaccine eight days to eight weeks before testing. (NOTE: paired sera must be tested in parallel).

OR

5. Detection of measles virus-specific IgM antibody confirmed in an approved reference laboratory EXCEPT if the case has received a measles-containing vaccine eight days to eight weeks before testing.

Clinical evidence

An illness characterised by all of the following:

1. A generalised maculopapular rash lasting three or more days

AND

2. Fever (at least 38 C if measured) at the time of rash onset

AND

3. Cough OR coryza OR conjunctivitis OR Koplik spots.

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:

a. one of them is likely to be infectious (approximately five days before to four days after rash onset)

AND

b. the other has an illness that starts within seven to 18 (usually 10) days after this contact

AND

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

Probable case

A probable case requires Laboratory suggestive evidence AND clinical evidence.

Laboratory suggestive evidence

Detection of measles specific IgM antibody other than by an approved reference laboratory EXCEPT if the case has received a measles-containing vaccine eight days to eight weeks before testing.

Clinical evidence

As with confirmed case.

In this section