Clinical Overview of Measles

Key points

  • Measles is one of the most contagious diseases. MMR vaccine provides the best protection.
  • Isolate infected patients for 4 days after they develop a rash and follow airborne precautions in healthcare settings.
  • Report suspected measles cases to your local health department.
  • Laboratory confirmation is essential for all sporadic measles cases and all outbreaks.
Photographed early in 2014 in the Philippines capital city of Manila, this baby was in a hospital with measles (rubeola). Since typhoon Haiyan, the Philippines, especially metropolitan Manila, has been experiencing a large measles outbreak.

Clinical features

Measles is an acute viral respiratory illness. It is characterized by:

  • A prodrome of fever (as high as 105°F), malaise, and cough, coryza, and conjunctivitis (three "C"s)
  • A pathognomonic enanthema (Koplik spots)
  • Followed by a maculopapular rash

The rash usually appears about 14 days after a person is exposed. The rash spreads from the head to the trunk to the lower extremities.

Patients are considered to be contagious from 4 days before to 4 days after the rash appears. Sometimes immunocompromised patients do not develop the rash.

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Measles is caused by a single-stranded, enveloped RNA virus with 1 serotype. It is classified as a member of the genus Morbillivirus in the Paramyxoviridae family. Humans are the only natural hosts of measles virus.

How it spreads

Measles is one of the most contagious of all infectious diseases. Up to 9 out of 10 susceptible people with close contact to a measles patient will develop measles.

The virus is transmitted by:

  • Direct contact with infectious droplets.
  • Airborne spread when an infected person breathes, coughs, or sneezes.

Measles virus can remain infectious in the air for up to 2 hours after an infected person leaves an area.

Disease rates

Prior to vaccine introduction:

The live measles vaccine was licensed in 1963. In the decade before, an average of 549,000 measles cases and 495 measles deaths were reported annually in the United States. However, it is likely that 3 to 4 million people on average were infected with measles annually; most cases were not reported. Of the reported cases, approximately:

  • 48,000 people were hospitalized from measles.
  • 1,000 people developed chronic disability from acute encephalitis caused by measles annually.

Post-vaccine era:

In 2000, measles was declared eliminated from the United States. However, cases and outbreaks still occur every year in the United States. This is because measles is still commonly transmitted in other countries in Europe, the Middle East, Asia, the Americas, and Africa.

Since 2000, the annual number of cases has ranged from a low of 37 in 2004; to a high of 1,282 in 2019. The majority of cases in the United States have been among people who are not vaccinated against measles.


Measles can be prevented with measles-containing vaccine, which is primarily administered as the combination measles, mumps, and rubella (MMR) vaccine. The combination measles-mumps-rubella-varicella (MMRV) vaccine can be used for children aged 12 months through 12 years for protection against all four viruses. Single-antigen measles vaccine is not available.

CDC recommends children get 2 doses of MMR vaccine. Teens and adults should also be up to date on their MMR vaccination. Almost everyone who does not respond to the measles component of the first dose of MMR vaccine at age 12 months or older will respond to the second dose. Therefore, the second dose of MMR is administered to address primary vaccine failure.1

While the most important measure to prevent measles transmission in all settings is ensuring community immunization, core measles prevention in healthcare settings requires a multi-faceted approach.

Diagnosis and laboratory testing

Testing recommendations for measles‎

A visual tool that summarizes what test types are typically available and when to collect specimens for testing measles, mumps, rubella, and varicella.

Consider measles in patients presenting with febrile rash illness and clinically compatible measles symptoms, especially if they recently traveled internationally; or were exposed to a person with febrile rash illness. Healthcare providers are required to report suspected measles cases to their local health department.

Laboratory confirmation is essential for all sporadic measles cases and all outbreaks. The most common methods for confirming measles infection are:

  • Detection of measles-specific IgM antibody in serum.
  • Measles RNA by RT-PCR in a respiratory specimen.

Obtain both a serum sample and a throat swab (or nasopharyngeal swab) from patients suspected to have measles at first contact with them. Urine samples may also contain virus. When feasible to do so, collecting both respiratory and urine samples can increase the likelihood of detecting measles virus.

Molecular analysis can also be conducted to determine the genotype of the measles virus. Genotyping is used to map the transmission pathways of measles viruses. The genetic data can help to link or unlink cases and can suggest a source for imported cases. Genotyping is the only way to distinguish between wild-type measles virus infection and a rash caused by a recent measles vaccination.

Patient management

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

Infected people should be isolated for 4 days after they develop a rash; airborne precautions should be followed in healthcare settings. Because of the possibility (albeit low) of MMR vaccine failure in healthcare providers exposed to infected patients, providers should observe airborne precautions in caring for patients with measles.

The preferred placement for patients who require airborne precautions is in a single-patient airborne infection isolation room (AIIR). Regardless of presumptive immunity status, all healthcare staff entering the room should use respiratory protection consistent with airborne infection control precautions. This includes use of an N95 respirator or a respirator with similar effectiveness in preventing airborne transmission.


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

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.

Who is at risk

People at high risk for complications include:

  • Infants and children aged <5 years
  • Adults aged >20 years
  • Pregnant people
  • People with weakened immune systems, such as from leukemia and HIV infection

Measles importation and outbreaks

Measles cases occur as a result of importations by people who were infected while in other countries; and from subsequent transmission that may occur from those importations. Measles is more likely to spread and cause outbreaks in communities where groups of people are unvaccinated.

Outbreaks in countries to which Americans often travel can directly contribute to an increase in measles cases in the United States. In recent years, measles importations have come from frequently visited countries and countries where large outbreaks were reported. These include but not limited to the Philippines, Ukraine, Israel, Thailand, Vietnam, England, France, Germany, and India.

International travelers‎

It is critical for all international travelers to be protected against measles, regardless of their destination. See videos on specific travel and measles vaccination case studies.

Resources and tools

Webinars & trainings

Testing tools

Measles is a mandatory, immediately notifiable disease.‎

CDC recommends that either a nasopharyngeal swab, throat swab, or urine specimen as well as a blood specimen be collected from all patients with clinical features compatible with measles.

PowerPoint presentations

Clinical Factsheets


Measles Clinical Features and Diagnosis

CDC commentaries & articles

  • Siegel JD, Rhinehart E, Jackson M, Chiarello L, and the Healthcare Infection Control Practices Advisory Committee, 2007 Guidelines for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings.
  • The measles-mumps-rubella-varicella (MMRV) vaccine is also available to children 12 months through 12 years of age. If used in place of MMR vaccine, the first dose should be administered at age 12 months or older, and the second dose no earlier than three months after the first dose. MMRV should not be administered to anyone older than 12 years of age.