Measles is a highly contagious virus that causes a febrile rash illness. The virus lives in the nose and throat mucus of an infected person and 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 up to 90% of the people close to that person who are not immune will become infected. A person is most infectious on the day their rash appears, but infected individuals can spread measles to others from 4 days before through 4 days after their rash onset date. Measles infection is a vaccine-preventable illness: two doses of MMR vaccine are about 97% effective at preventing measles, and even one dose is about 93% effective.


Clinical Presentation

The average incubation period for measles is 10–12 days (range: 7–21 days) from the date of the initial exposure until early signs and symptoms appear.
  • Early symptoms of measles include a fever (as high as 105°F),malaise, cough, coryza (runny nose), and conjunctivitis (red/watery eyes).
  • 2–3 days after symptoms begin, tiny white spots may appear inside the mouth (Koplik spots).
  • 3–5 days after symptoms begin, a maculopapular skin rash develops that begins on the face at the 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.
When considering measles, healthcare providers should consider the progression of symptoms. Fever and the three “C’s” (cough, coryza, conjunctivitis) almost always appears before the onset of a rash. The rash classically starts on the face and head and spreads down towards the extremities.  Providers should also consider diagnoses including other viral exanthems and drug reactions (e.g., antibiotics, contact dermatitis). Other common causes of febrile rash in children include, parvovirus B-19 (Fifth disease), human herpesvirus 6 (Sixth disease or Roseola), and enteroviruses.



Common complications from measles include otitis media, bronchopneumonia, laryngotracheobronchitis, and diarrhea.

People at high risk for complications include infants and children aged <5 years, adults >20 years, pregnant people, and people with weakened immune systems such as from leukemia and HIV infection.

Even in previously healthy children, measles can cause serious illness requiring hospitalization.
  • 1 out of every 1,000 measles cases will develop acute encephalitis, which often results in permanent brain damage.
  • 1 to 3 out of every 1,000 children who become infected with measles will die from respiratory and neurologic complications.
  • Subacute sclerosing panencephalitis (SSPE) is a rare, but fatal degenerative disease of the central nervous system characterized by:
    • Behavioral and intellectual deterioration.
    • Seizures that generally develop 7 to 10 years after measles infection

Clinical Evaluation and Testing

What do I do if an individual presents with rash and fever?
Query patients about a history of international travel, history of domestic travel to areas with ongoing outbreaks, contact with foreign visitors, transit through an international airport, or possible exposure to a measles patient in the three weeks prior to symptom onset. Suspect measles in patients with compatible clinical presentation and such a history.
See the measles evaluation algorithm  for support when evaluating patients with febrile rash illnesses: 

  1. This testing algorithm is intended to be used by bedside providers in settings where there is no local measles transmission. This assumes that the pre-test probability will be low for most people without known epidemiologic risk for measles and who do not meet case criteria. If there is active transmission in the Chicagoland area, CDPH will update testing recommendations with a lower threshold for testing. 
  2. Either a measured or patient/family-reported fever is adequate; fever may not be measured at the time of healthcare evaluation due to normal fluctuation or to use of antipyretics (e.g., ibuprofen). 
  3. A vesicular rash is not consistent with measles, and should prompt consideration for other causes of rash (e.g., varicella/chickenpox)
  4. Measles clinical criteria (per CSTE* case definition) include ALL of the following: 
    • Generalized, maculopapular rash
    • Fever
    • Cough, coryza (runny nose), or conjunctivitis
  5. Up to 5% of MMR recipients will get a short-lived, mild febrile rash. This is more common with the first dose of MMR. People who experience this vaccine reaction are not contagious to others around them. If a person has received MMR within 21 days before rash onset, but also has epidemiologic risk for measles, then specialized testing may be required and should be discussed with local or state public health authorities.

Next steps After Measles is Suspected

If you suspect a patient hase measles, follow the steps below.  See the Measles Job Aid for additional details.


ISOLATE:  Promptly isolate the patient and notify your facility’s infection prevention team of the suspect measles case. 


NOTIFY: Report suspected measles cases to the local health department immediately, and at first clinical suspicion. To report a suspect case in a Chicago resident, call CDPH at 312-743-9000 during business hours or 311 after hours and on weekends. 


TEST:  Laboratory confirmation is essential for all sporadic measles cases and all outbreaks. Collect specimens as soon as possible after rash onset.  
  • Collect a nasopharyngeal or oropharyngeal swabs for measles RT-PCR. The Illinois Department of Public Health Laboratory (PHL) provides measles PCR testing at no cost to the patient and provider and has a typical turnaround time of 1 day. Contact CDPH to facilitate testing at the PHL. CDPH strongly advises PCR testing is conducted at the PHL and not at a commercial lab, as testing at commercial labs can delay results.  
  • Obtain serum for measles IgM and IgG. Serum should be sent to your facility’s normal commercial or clinical laboratory. Measles virus is also referred to as “rubeola” in some lab orders, not to be confused with rubella virus. isolate the patient and notify your facility’s infection prevention team of the suspect measles case. 


Manage: While awaiting testing results: 
  • Any exam room(s) the patient was in should be closed down for at least 2 hours after patient has left. 
  • If the patient is being admitted, they need to be placed on airborne precautions. 
  • If the patient is being discharged to home, they should be instructed to stay home and have no visitors until test results are back. 
  • Begin collecting information on staff and other patients who were in the area during the time the suspect measles patient was in the facility and for two hours after they left. If the case is confirmed, contact tracing will need to be conducted.  


The best way to prevent measles infection is through vaccination with the MMR vaccine. Vaccines containing measles antigen currently licensed in the United States are the multi-antigen vaccines MMR II and MMRV (manufactured by Merck). Both are live attenuated virus vaccines.

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.

For international travelers:
People 6 months of age and older who will be traveling internationally should be protected against measles, regardless of international destination.
  • Infants aged 6 through 11 months should also receive one dose of MMR before departure.
  • Children 12 months of age or older should have documentation of two doses of MMR vaccine (the first dose of MMR vaccine should be administered at age 12 months or older; the second dose no earlier than 28 days after the first dose). 
  • Teenagers and adults born during or after 1957 without evidence of immunity against measles should have documentation of two doses of MMR vaccine, with the second dose administered no earlier than 28 days after the first dose.
See CDC MMR vaccine guidance for additional details on vaccination for patients planning international travel: https://www.cdc.gov/vaccines/vpd/mmr/hcp/recommendations.html  


There is no specific antiviral therapy for measles. Medical care is supportive and to help relieve symptoms and address complications such as bacterial infections.

Severe measles cases among children, such as those who are hospitalized, should be treated with vitamin A. Vitamin A should be administered immediately on diagnosis and repeated the next day. The recommended age-specific daily doses are:
  • 50,000 IU for infants younger than 6 months of age
  • 100,000 IU for infants 6–11 months of age
  • 200,000 IU for children 12 months of age and older
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Post-Exposure Prophylaxis

People who are exposed to measles who cannot readily show that they have evidence of immunity against measles should be offered post-exposure prophylaxis (PEP) if eligible. MMR vaccine can be used as PEP if administered within 72 hours of initial measles exposure, and immunoglobulin can be used as PEP if administered within 6 days of exposure. Please contact CDPH to discuss PEP if you suspect or have diagnosed measles.  

Infection Prevention & Control

For details on management of suspected or confirmed measles patients in healthcare settings, please refer to the Provider Job Aid.

For exposures in schools, please call 312-746-6015 for further guidance. For exposures in shelters, please call 312-743-9000 for further guidance.

Additional Resources

Measles Reporting

Suspect cases should be reported immediately, within 3 hours of clinical suspicion. Do not wait for laboratory confirmation.
To Report Suspect Cases:
  • Call 312-743-9000 during business hours and select option 2.
  • After-hours, weekends, holidays, or if you are unsuccessful using the number above, call 311 (or 312-744-5000 if outside the City of Chicago) and request the CDPH medical director on-call.
Schools: Please Click Here For Reporting and Management Information

Please consult the Measles Job Aid for more information on reporting, testing, and infection prevention and control practices.

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