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Case definition

Confirmed case 

Clinical illness and laboratory confirmation of infection in the absence of recent immunization with mumps-containing vaccine (i.e., within the previous 28 days):  

  • Isolation of mumps virus from an appropriate clinical specimen OR
  • Detection of mumps virus RNA OR
  • Significant (e.g. fourfold or greater) rise or seroconversion in serum mumps IgG titre by any standard serologic assay between acute and convalescent sera OR
  • Positive serologic test for IgM antibody in a person who is epidemiologically linked to a laboratory-confirmed case or has recently travelled to an area of known mumps activity 

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

Probable case

Mumps-compatible illness in the absence of a laboratory confirmation of infection and not epidemiologically linked to a laboratory-confirmed case.   

Suspect case

Illness that could be mumps but without parotitis or orchitis, in a person who is a contact of a confirmed or clinical mumps case.

Definition of clinical illness 

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

IgM antibody

IgM serology has the potential for false positive and false negative findings. 

If the clinical presentation is inconsistent with a diagnosis of mumps or in the absence of recent travel or exposure history, IgM result must be confirmed by the other listed confirmatory methods. In a mumps case that had been previously immunized, the IgM class antibody response may not be detectable.

SOURCE: Mumps ( )
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