National case definition: Mumps

Date of last revision/review: May 2008

National notification

Only confirmed cases of disease should be notified.

Type of surveillance

Routine case-by-case notification to the federal level.

Case classification

Confirmed case

Clinical illness (see Clinical evidence section) and laboratory confirmation of infection in the absence of recent immunization (see Clinical evidence section) with mumps-containing vaccine:

• isolation of mumps virus from an appropriate clinical specimen

or

• detection of mumps virus RNA

or

• seroconversion or a significant rise (e.g. fourfold or greater) in mumps IgG titre by any standard serologic assay between acute and convalescent sera

or

• positive serologic test for mumps IgM antibody (see Laboratory comments section) in a person who is either epidemiologically linked to a laboratory-confirmed case or has recently travelled to an area of known mumps activity

or

Clinical illness in a person with an epidemiologic link to a laboratory-confirmed case

Probable case

Clinical illness

• in the absence of appropriate laboratory tests

or 

• in the absence of an epidemiologic link to a laboratory-confirmed case.

Laboratory comments

IgM serology has the potential for false-positive findings. If the clinical presentation is inconsistent with a diagnosis of mumps or in the absence of recent travel/exposure history, IgM results must be confirmed by the other listed confirmatory methods.

Further strain characterization is indicated for epidemiologic, public health and control purposes.

Clinical evidence

Clinical illness is characterized by acute onset of unilateral or bilateral tender, self-limited swelling of the parotid or other salivary gland, lasting > 2 days, and without other apparent cause.

The most frequent reaction to measles-mumps-rubella (MMR) immunization is malaise and fever (with or without rash) occurring 7-12 days after immunization.  Parotitis has occasionally occurred after immunization.  However, this should be determined for each case, as these reactions and the time frame can vary (Canadian Immunization Guide, 7^th edition).

A laboratory-confirmed case may not exhibit clinical illness, as up to 30% of cases are asymptomatic.

ICD code(s)

ICD-10 code(s)

B26 Mumps

ICD-9/ICD-9CM code(s)

072 Mumps

Comments

The case definitions for mumps provided in this document are for routine surveillance purposes. Probable case definitions are provided as guidelines to assist with case finding and public health management, and are not for national notification purposes. Readers are referred to the document Laboratory Guidelines for the Diagnosis of Mumps (2007) for further information on the collection, transport, laboratory testing and laboratory test interpretation of specimens suspected of mumps.

References

Public Health Agency of Canada. Laboratory Guidelines for the Diagnosis of Mumps (PDF format). 2007.  Retrieved May 2008 from: http://www.nml-lnm.gc.ca/guide/docs/Mumps_Lab_guide.pdf

Previous case definitions

Canadian Communicable Disease Surveillance System: disease-specific case definitions and surveillance methods. Can Dis Wkly Rep 1991;17(S3).

Case definitions for diseases under national surveillance. CCDR 2000;26(S3).