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NOTE: A surveillance case definition is a set of uniform criteria used to define a disease for public health surveillance. Surveillance case definitions enable public health officials to classify and count cases consistently across reporting jurisdictions. Surveillance case definitions are not intended to be used by healthcare providers for making a clinical diagnosis or determining how to meet an individual patient’s health needs.

Clinical Description

An illness characterized by all the following:

  • A generalized rash lasting greater than or equal to 3 days
  • A temperature greater than or equal to 101.0°F (greater than or equal to 38.3°C)
  • Cough, coryza, or conjunctivitis

Laboratory Criteria For Diagnosis

  • Positive serologic test for measles immunoglobulin M antibody, OR
  • Significant rise in measles antibody level by any standard serologic assay, OR
  • Isolation of measles virus from a clinical specimen

Case Classification


Any febrile illness accompanied by rash


A case that meets the clinical case definition, has noncontributory or no serologic or virologic testing, and is not epidemiologically linked to a confirmed case


A case that is laboratory confirmed or that meets the clinical case definition and is epidemiologically linked to a confirmed case. A laboratory-confirmed case does not need to meet the clinical case definition.


Confirmed cases should be reported to National Notifiable Diseases Surveillance System (NNDSS). An imported case has its source outside the country or state. Rash onset occurs within 18 days after entering the jurisdiction, and illness cannot be linked to local transmission. Imported cases should be classified as:

  • International. A case that is imported from another country
  • Out-of-State. A case that is imported from another state in the United States. The possibility that a patient was exposed within his or her state of residence should be excluded; therefore, the patient either must have been out of state continuously for the entire period of possible exposure (at least 7-18 days before onset of rash) or have had one of the following types of exposure while out of state: a) face-to-face contact with a person who had either a probable or confirmed case or b) attendance in the same institution as a person who had a case of measles (e.g., in a school, classroom, or day care center).

An indigenous case is defined as a case of measles that is not imported. Cases that are linked to imported cases should be classified as indigenous if the exposure to the imported case occurred in the reporting state. Any case that cannot be proved to be imported should be classified as indigenous.

Related Case Definition(s)