Information About Measles Information About Measles




Measles is a highly contagious virus that lives in the nose and throat mucus of an infected person. It can spread to others through coughing and sneezing. Measles can live for up to 2 hours in an airspace where the infected person coughed or sneezed. Measles is so contagious that if one person has it 90% of the people close to that person who are not immune will become infected.  Infected individuals can spread measles to others from 4 days before through 4 days after the rash appears.  Measles infection is a vaccine-preventable illness.

Symptoms include:

  • High fever
  • Cough
  • Runny nose
  • Red/watery eyes
  • Tiny white spots that may appear inside the mouth (Koplik spots) 2-3 days after symptoms begin  

The rash starts 3-5 days after symptoms, usually beginning as flat red spots that appear on the face at hairline and spreads downward to the neck, trunk, arms, legs, and feet. Small raised bumps may also appear on the top of the flat red spots. The spots may become joined together as they spread. As rash appears an individual’s fever may spike.

Severe infections can result in pneumonia or encephalitis. The average incubation period for measles is 10-12 days (range: 7-21 days).


The best way to prevent measles infection is through vaccination with the MMR vaccine. Children should receive 2 doses:

  • 1st dose at 12-15 months of age
  • 2nd dose between 4-6 years of age

Adults might also need the vaccine if they were not immunized as children. Vaccines containing measles antigen that are currently licensed in the United States are the multi-antigen vaccines MMR II and MMRV (manufactured by Merck).  Both are live attenuated virus vaccines.


  1. Collect specimens as soon as possible after rash onset. Throat swabs are preferred. Nasal swabs or washes are acceptable but not preferred.
  2. Since April 2018, CDPH is recommending that if providers suspect measles, that they call CDPH immediately for guidance and coordination of diagnostic testing which includes measles IgM antibody testing and the measles RNA real-time polymerase chain reaction (RT-PCR).
  3. Viral culture is an alternative method if PCR is not available.  A positive RT-PCR test or a positive culture confirms the diagnosis.
Measles Contact Us Measles Contact Us

Contact Us

For Questions  or to Report Cases Contact:


For Surveillance Questions Contact:

Enrique Ramirez, Epidemiologist


For questions during non-business hours call 311. (312-744-5000 if outside the City of Chicago.)

 Suspect Cases should be reported within 24 Hours.  Do not wait for laboratory confirmation.


Measles Case Definition Measles Case Definition

Case Definition

Confirmed Case:

An acute febrile rash illness with:

  • Isolation of measles virus from a clinical specimen; or
  • Detection of measles from a clinical specimen using PCR; or
  • IgG seroconversion or a significant rise in measles immunoglobulin G antibody using any evaluated and validated method; or
  • A positive serologic test for measles immunoglobulin M antibody; or
  • Direct epidemiologic linkage to a case confirmed by one of the methods above.