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.
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.
Cause
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 vaccination 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.
Prevention
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.
- One dose of MMR vaccine is approximately 93% effective at preventing measles.
- Two doses are approximately 97% effective.
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
Administration recommendations
For children:
CDC recommends routine childhood immunization for MMR vaccine starting with the first dose at 12 through 15 months of age, and the second dose at 4 through 6 years of age or at least 28 days following the first dose.
The MMRV vaccine is also available to children 12 months through 12 years of age; the minimum interval between doses is three months.
For students:
Students at post-high school educational institutions without evidence of measles immunity need two doses of MMR vaccine, with the second dose administered no earlier than 28 days after the first dose.
For international travelers:
People 6 months of age or older who will be traveling internationally should be protected against measles. Before traveling internationally,
- Infants 6 through 11 months of age should receive one dose of MMR vaccine.A
- 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).B
- 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.
For healthcare personnel:
Healthcare personnel should have documented evidence of immunity against measles, according to the ACIP recommendations for immunizing personnel.
For adults:
People who are born during or after 1957 who do not have evidence of immunity against measles should get at least one dose of MMR vaccine.
Some people should not get MMR or MMRV vaccine.
MMR Vaccine Information for Healthcare Providers
Who Should NOT Get Vaccinated with MMR
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
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.
Acceptable presumptive evidence of immunity against measles includes at least one of the following:
- Written documentation of adequate vaccination:
- One or more doses of a measles-containing vaccine administered on or after the first birthday for preschool-age children and adults not at high risk
- Two doses of measles-containing vaccine for school-age children and adults at high risk, including college students, healthcare personnel, and international travelers
- Laboratory evidence of immunityA
- Laboratory confirmation of measles
- Birth before 1957
Healthcare providers and health departments should not accept verbal reports of vaccination without written documentation as presumptive evidence of immunity.
People exposed to measles who cannot readily show that they have evidence of immunity against measles should be offered post-exposure prophylaxis (PEP).
To potentially provide protection or modify the clinical course of disease among susceptible persons, administer one of these:
- MMR vaccine within 72 hours of initial measles exposure.
- Immunoglobulin (IG) within 6 days of exposure.
Do not administer MMR vaccine and IG simultaneously, as this practice invalidates the vaccine.
Please refer to the following references for additional information on post-exposure prophylaxis:
Complications
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.
- Behavioral and intellectual deterioration.
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
Resources and tools
Webinars & trainings
Testing tools
Measles is a mandatory, immediately notifiable disease.
PowerPoint presentations
Clinical Factsheets
Measles Clinical Diagnosis Fact Sheet
Videos
Measles Clinical Features and Diagnosis
CDC commentaries & articles
- Infants who get one dose of MMR vaccine before their first birthday should get two more doses according to the routinely recommended schedule (one dose at 12 through 15 months of age and another dose at 4 through 6 years of age or at least 28 days later).
- 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.
- 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.