Measles Outbreak Toolkit

Measles Outbreak Toolkit

Updated | September 2022

Welcome to the Measles Outbreak Toolkit

Key reference documents

Case definitions

WHO suggested outbreak case definitions

Case definitions for case finding

Suspected case:

An illness in a patient with fever and generalized maculopapular (non-vesicular) rash, or in a patient whom a health care worker suspects has measles. 

Clinical measles case:

Any person in whom a clinician suspects measles infection; or 

Any person with fever and maculopapular rash (i.e., non-vesicular) and: 

  • cough, or 
  • coryza (i.e., runny nose) or 
  • conjunctivitis (i.e., red eyes).

Final case classifications

Laboratory-confirmed measles case:

A suspected case of measles that has been confirmed positive by testing in a proficient laboratory, and vaccine-associated illness has been ruled out1

Epidemiologically linked measles case:

A clinical case of measles that has not been confirmed by a laboratory, but was geographically and temporally related, with dates of rash onset occurring 7–21 days apart from a laboratory-confirmed case or another epidemiologically linked measles case.

Clinically compatible measles case:

A clinical case of measles, but no adequate clinical specimen was taken and the case has not been linked epidemiologically to a laboratory-confirmed or epidemiologically linked case of measles or other communicable disease.

Discarded case:

A suspected measles case that has been investigated and discarded as non-measles through:

  • negative laboratory testing in a proficient laboratory on an adequate specimen collected during the proper time after rash onset; or
  • epidemiological linkage to a laboratory-confirmed outbreak of another communicable disease that is not measles; or
  • confirmation of another etiology; or
  • failure to meet the clinically compatible measles case definition.

WHO surveillance case definitions

Measles: Surveillance standards for vaccine-preventable diseases (2nd edition) (Geneva: World Health Organization; 2018)‎.

WHO other definitions

Definition of measles outbreak

Suspected measles outbreak:

Five or more measles cases (with dates of rash onset occurring 7–21 days apart) that are epidemiologically linked.

Laboratory-confirmed measles outbreak:

Two or more laboratory-confirmed measles cases that are temporally related (with dates of rash onset occurring 7–21 days apart) and epidemiologically or virologically linked, or both

Acute measles-related death

A measles-related death is a death in an individual with confirmed (clinically, laboratory or epidemiologically) measles in which death occurs within 30 days of rash onset and is not due to other unrelated causes, e.g., a trauma.

1. Confirmation methods:

  • Detection of anti-measles IgM antibody by enzyme immunoassay (EIA). This is the gold standard. Results of IgM should be reported within four days of the specimen’s arrival at the laboratory. 
  • Diagnostically significant titre change in anti-measles IgG antibody level in acute or convalescent sera, or documented seroconversion (IgG negative to IgG positive).
  • Positive reverse transcription-polymerase chain reaction (RT-PCR) or viral isolation in cell culture.

    Measles Outbreak Guide (Geneva: World Health Organization; 2022). 

 

Data collection tools

 

Laboratory confirmation

Response tools and resources

Training

Other resources