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Last updated: 5/15/2025
Years published: 1987, 1989, 1990, 1997, 2005, 2025
NORD gratefully acknowledges Gioconda Alyea, MD (FMG), MS, National Organization for Rare Disorders, for assistance in the preparation of this report.
Introduction
Measles is a very contagious illness that spreads easily, even in public spaces without someone having direct contact with an infected person. People who are not vaccinated and are exposed to measles have a 90% chance of getting sick.1
Due to the vaccine, measles was officially eliminated from the United States in 2000, meaning measles was no longer spreading within the country and new cases were only found when someone contracted measles abroad and returned to the country. However, there have been some outbreaks in recent years, including a large outbreak in 2025, resulting in 2 deaths and multiple hospitalizations.2
Measles usually starts with flu-like symptoms such as fever, malaise, cough, runny nose (rhinitis) and pink eye (conjunctivitis) followed by a rash. The rash spreads from the head to the trunk to the lower extremities.3 People with measles are contagious from about five days before the rash appears until about four days after.1
Measles is caused by a virus. Humans are the only natural hosts of measles virus.3
Measles can lead to serious problems, especially in young children, pregnant women and people with weakened immune systems.1
There is no specific cure for measles, so treatment focuses on relieving symptoms and preventing complications. The best way to prevent measles is through vaccination.1,4
Classic measles infection consists of the following clinical stages: incubation, early symptoms (prodrome), appearance of rash (exanthem) and recovery. 1,3
Measles can lead to serious problems, especially in young children, pregnant women and people with weakened immune systems. About 1 in 3 people with measles develop complications such as:1
Measles also weakens the immune system, making it more likely to catch other infections for months or even years afterward.
Clinical variants include modified measles and atypical measles.1,3
Congenital measles can occur in a baby when the pregnant mother has measles. Infants with congenital measles have measles symptoms at birth or within the first 10 days of life. The symptoms can range from mild to severe. Some babies may have no symptoms, while others may develop rash, pneumonia (lung infection), eye inflammation (keratitis) or diarrhea (gastroenteritis) and have an increased risk for death without any treatment. Additionally, babies with congenital measles face a higher chance of developing a rare but serious brain condition called subacute sclerosing panencephalitis (SSPE), which can appear years later. In some cases, if a pregnant person gets measles, it can increase the chances of having miscarriage, stillbirth, or a premature birth (being born too early).3,4
Measles is caused by the measles virus, a type of virus that belongs to a group called Morbillivirus which is part of a larger virus family known as Paramyxoviridae. The virus lives in the mucus in the nose and throat of an infected person and is spread into the air when the infected person sneezes or coughs. It has a single strand of genetic material called RNA, which is basically the virus’s instruction manual for making more copies of itself.3,5
Interestingly, the measles virus is related to some animal viruses, like the one that causes distemper in dogs. Primates (like monkeys) can be infected in lab settings, but humans are the only species that naturally carry and spread the measles virus. This means, in theory, if we vaccinated enough people worldwide, we could completely wipe out the virus.5
Scientists have studied the entire genetic makeup (genome) of the measles virus. This has helped them identify different versions (lineages) of the virus that tend to show up in specific parts of the world. By comparing the virus from an outbreak to these known lineages, experts can often figure out where the outbreak started.5
Even though there are different strains of the measles virus, the vaccine works against all of them. This is because measles is considered a monotypic virus meaning it has only one main type that the immune system learns to recognize and fight off.3,5
Measles is one of the most contagious of all infectious diseases. Up to 9 out of 10 susceptible people with close contact to a person with measles will develop measles.3
The measles virus may be transmitted through:1
Most cases of measles occur in people who haven’t been vaccinated.
Before the measles vaccine was introduced, an estimated 48,000 people were hospitalized and 400–500 people died in the United States each year due to measles. Measles was officially eliminated (eradicated) from the United States in 2000, meaning no measles was spreading within the country and new cases were only found when someone contracted measles abroad and returned to the country. Achieving measles elimination status in the United States was a historic public health achievement.1,2,6,7 However, there have been measles outbreaks in recent years, mainly among unvaccinated populations, including a large outbreak in the early months of 2025, which resulted in 2 deaths and multiple hospitalizations. See the CDC information about the cases of measles in United States.2,7
Measles is not a seasonal virus. However, measles is often spread during times of high travel (like spring break) or in situations where unvaccinated people are in close quarters (like summer camp).
Measles is still common in many developing countries, especially in certain parts of Africa and Asia, due to poor access to vaccines. Most measles-related deaths (more than 95%) occur in low-income countries with weak health infrastructures. Vaccination has had a major impact on reducing measles deaths. During 2000-2015, measles vaccination prevented an estimated 20.3 million deaths.8
Diagnosis of measles is based on medical history, signs and symptoms and some specific tests.
Doctors suspect measles if a person has:1
People who are suspected of having measles should be isolated immediately to prevent the spread of the virus.
Doctors diagnose measles using:
These tests help confirm measles and rule out other illnesses.
Treatment
There is no specific cure for measles, so treatment focuses on relieving symptoms and preventing complications. The best way to prevent measles is through vaccination (see Prevention below).
Supportive care is normally all that is required for people with measles. Supportive care includes:1
Severe cases may require hospital care, especially if there are complications like pneumonia or brain inflammation (encephalomyelitis), bacterial superinfection, dehydration or croup. Croup is a common respiratory infection that primarily affects young children, characterized by swelling and inflammation of the upper airway, leading to a barking cough and difficulty breathing.
Vitamin A has been shown to reduce severe illness and death in children with measles, especially in developing countries. It can help prevent eye damage and blindness. The World Health Organization (WHO) recommends vitamin A for all children with measles, no matter where they live. In the U.S., children with severe measles often have low vitamin A levels. The recommendations are:1
It is important to note that vitamin A does not prevent measles. In 2019, the National Foundation for Infectious Diseases (NFID) convened a group of national experts to clarify the use of vitamin A in treating severe cases of measles. Since then, the World Health Organization, American Academy of Pediatrics, the U.S. Centers for Disease Control and Prevention (CDC) and the NFID have aligned on using vitamin A for the management of children hospitalized with measles.1,3 View Report
See also the CDC: Frequently Asked Questions about Measles.
Ribavirin (antiviral medication) is sometimes used as a treatment in severe cases, especially for infants, hospitalized patients, or those with weak immune systems.
Secondary infections like ear infections (otitis media) or bacterial lung infections (bacterial pneumonia) should be treated with antibiotics. Occasionally, administering fluids directly into a vein to treat or prevent dehydration (intravenous rehydration) is required. Fever management with standard anti-fever medication is appropriate.1,3
Prevention
Measles vaccine (MMR vaccine): The best protection against measles is the MMR vaccine which also protects against mumps and rubella and is over 97% effective in preventing measles. It is given in two doses: 1,3
However, CDC recommends that any infant as young as 6 months old who will be traveling internationally should get a vaccine before leaving the U.S., followed by 2 additional doses later. Vaccination protects both individuals and the community through herd immunity.3
Adolescents (preteens and teens) who were not previously vaccinated should get 2 doses (with at least 28 days between doses); those who only received 1 dose previously should receive a second dose.3
All adults born in 1957 or later who have not been vaccinated and have not had measles should be vaccinated. Those vaccinated between 1963-1968 may have received a measles vaccine that was found to be less effective. If a person is not sure whether they were vaccinated, it is safe to get another measles vaccine.3
The only people who should not get a measles vaccine are those who are immunocompromised or pregnant, or those who have had an allergic reaction to previous vaccine (rare, ~1 in a million).3
During their October 2024 session, the Advisory Committee on Immunization Practices (ACIP) endorsed the recommended Immunization Schedule for Children and Adolescents up to 18 Years Old in the United States for the year 2025.1 The child and adolescent immunization schedule can be found on the CDC immunization schedule website.
As stated before, in the U.S., the measles vaccine is usually part of the MMR vaccine (measles, mumps, rubella). There are two options:1
Infection Control
In regions of low measles prevalence, cases of suspected or confirmed measles should be reported to the local health authorities, who provide guidance on specimen collection for diagnosis as well as infection control interventions.1,2,3
The American Academy of Pediatrics (AAP) has updated its guidelines on measles. These changes cover proof of immunity, immune globulin use, vaccination for healthcare workers and management of people with HIV or weakened immune systems.1
A person is considered immune to measles if they meet any of the following criteria:
If someone has been exposed to measles and doesn’t have immunity, doctors may give immune globulin (a type of antibody treatment) within 6 days of the exposure to help prevent or lessen the infection.1
Healthcare workers (including medical students) are at higher risk of exposure, so the guidelines include:
People with weakened immune systems (like those on certain treatments) need special care after measles exposure:1
Important: Measles can be deadly for people with HIV, so protection is essential.
For additional information about measles see the following sources:
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website:
https://rarediseases.org/living-with-a-rare-disease/find-clinical-trials/
For information about clinical trials sponsored by private sources, contact: www.centerwatch.com
For information about clinical trials conducted in Europe, contact: https://www.clinicaltrialsregister.eu/
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NORD and MedicAlert Foundation have teamed up on a new program to provide protection to rare disease patients in emergency situations.
Learn more https://rarediseases.org/patient-assistance-programs/medicalert-assistance-program/Ensuring that patients and caregivers are armed with the tools they need to live their best lives while managing their rare condition is a vital part of NORD’s mission.
Learn more https://rarediseases.org/patient-assistance-programs/rare-disease-educational-support/This first-of-its-kind assistance program is designed for caregivers of a child or adult diagnosed with a rare disorder.
Learn more https://rarediseases.org/patient-assistance-programs/caregiver-respite/