Measles


by Hal B. Jenson, M.D.
Chief, Pediatric Infectious Diseases
University of Texas Health Science Center
San Antonio, TX
and
by Charles T. Leach, M.D.
Associate Professor of Pediatrics
University of Texas Health Science Center
San Antonio, TX

What is measles?

Measles, also commonly known as “rubeola,” is a viral infection that is characterized
primarily by a fever, a cough, a runny nose, red eyes, a rash, and spots inside
the mouth.

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What causes measles?

The measles virus, an RNA virus of the paramyxovirus family of viruses, causes measles.

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Who gets measles?

Measles was an important disease that occurred in almost all children before the
introduction of the measles vaccine. Measles is highly contagious, and, historically,
it has caused large outbreaks. Prior to the use of the measles vaccine, which was
introduced in 1963, more than 500,000 cases of measles were reported each year in
the United States. The disease is now very uncommon. In 1998, only approximately
100 cases were reported in the United States.

Today, measles is usually seen only in those persons who have not received the vaccine,
typically, in children one to four years of age. Most cases in the United States
have occurred in inner city or isolated rural areas, where poverty is common and
access to health care, including measles vaccination, is difficult, or in persons
traveling to or visiting from other countries.

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How does the measles virus cause disease?

The measles virus is transmitted from person-to-person by direct contact or by contaminated
secretions of the nose and the mouth. The measles virus infects the lining of the
nose and the upper respiratory tract. Then, it is spread through the blood throughout
the body, which causes the rash. In the lungs, the measles virus infection can cause
pneumonia, which can be severe and life threatening, especially in infants.

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What are the common findings?

Measles can be divided into four phases: 1) the incubation phase, 2) the prodromal
(catarrhal) phase, 3) the rash phase, and 4) the recovery phase.

The incubation phase typically lasts 8 to 12 days after exposure to the virus and
does not have any symptoms. The prodromal phase begins at the onset of the first
symptoms, which begin gradually and include a fever, a cough, a runny nose, and
red eyes. Usually, the fever is the first symptom noticed by parents. The fever
rises steadily and may reach maximum temperatures of 103F to 104F. At the height
of the fever, the rash develops.

The runny nose with a profuse watery discharge, nasal congestion, and sneezing becomes
prominent. Typically, there is a pronounced cough, which is hoarse, dry, and hacking.
Some children may complain of tightening in the chest. The red eyes are characterized
by increased tearing, eye pain that may be severe, and sensitivity to light. Other
symptoms that are frequently observed during the prodromal phase include fatigue,
irritability, a decreased appetite, a headache, abdominal pain, and a dry mouth
and throat.

Approximately two to four days after the onset of the symptoms, the rash appears,
marking the beginning of the rash phase. The symptoms of the prodromal phase worsen
with the onset of the rash, but then begin to decrease in severity. The measles
rash is a flat or slightly raised rash, and is not itchy. It first appears as irregular
spots on the upper forehead or behind the ears and on the neck. Within 24 hours,
it progresses to the entire face, head, and neck. Over the next two to four days,
the rash extends to the chest, back, and extremities, including the palms of the
hands and the soles of the feet. It remains most prominent on the face, especially
on the cheeks.

After four to five days, the rash begins to subside, marking the beginning of the
recovery phase. Sometimes, a very fine flaking of the skin is noted as the rash
fades. About 10 to 14 days after developing the rash, the child is back to a normal
level of activity.

One of the characteristic findings of measles is the presence of spots, known as
“Koplik spots,” inside the mouth. These tiny pinpoint blue-white spots begin as
a few lesions on the inside of the cheeks, typically occurring 1 to 2 days before
the rash, and increase rapidly in number over the next 24 hours. They begin to fade
as the rash appears, and usually disappear by the second day of the rash.

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How is measles diagnosed?

Measles is diagnosed primarily on the clinical and physical examination findings.
The appearance of the rash is characteristic, and when found in association with
Koplik spots inside the mouth, an experienced physician can diagnose measles. There
also is a specific antibody blood test that can be used to confirm the diagnosis.

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How is measles treated?

There is no specific treatment for measles. Antibiotics are not helpful because
a virus causes measles. Viruses cannot be treated with antibiotics. The disease
is usually mild with complete recovery. Some children, especially infants and young
children, require hospitalization for intravenous fluids and occasionally because
of severe pneumonia. The fever should be treated with acetaminophen or ibuprofen.

Severe measles has been associated with very low levels of vitamin A. In developing
countries, vitamin A supplements appear to improve the course of measles, especially
in children younger than two years of age. In the United States, the American Academy
of Pediatrics recommends vitamin A supplements for certain children with measles
who are not already receiving additional daily vitamin A. Children who might need
additional vitamin A include those with:

  • Immunodeficiency
  • Signs of vitamin A deficiency, such as night blindness or dry eyes
  • Impaired gastrointestinal absorption
  • Moderate to severe malnutrition
  • Recent immigration from an area of increased problems with measles
  • Hospitalization with measles or its complications

For these children, a single dose of vitamin A (100,000 IU for infants, 6 months
to 1 year of age; 200,000 IU for older children) is given at the time that measles
is diagnosed. Excess vitamin A can be dangerous for the developing fetus of pregnant
women.

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What are the complications?

The most frequent complications of measles are diarrhea, middle ear infection (“bacterial
otitis media”), bacterial pneumonia, and inflammation of the brain (“encephalitis”).
Diarrhea is the most common complication of measles in the United States, and it
occurs in approximately 10% of children who develop measles. The diarrhea usually
begins after the rash appears, lasts for only a few days, and usually does not require
hospitalization for intravenous fluids. Otitis media occurs in approximately 5%
to 15% of children with measles, and usually begins during the second week of illness
after the rash has faded.

Pneumonia is one of the most serious complications of measles, and it can be caused
either by the measles virus itself or by bacteria that cause additional infection
during the course of measles. Children who have an immunodeficiency are at a particularly
high risk for pneumonia with measles.

Acute encephalitis (inflammation of the brain) is an uncommon complication of measles
and occurs in approximately 1 to 2 of every 1,000 cases of measles. It is a more
serious complication because it can be very severe and can lead to death.

Subacute sclerosing panencephalitis (SSPE) is a very rare, but fatal, form of degenerative
encephalitis (inflammation of the brain) that develops an average of 8 to 10 years
after a typical case of measles. SSPE occurs in approximately one out of every one
million persons with measles. The onset is usually very gradual, but results in
behavioral changes and impairment of intellectual function, leading to seizures,
coma, and death in a few years. Patients with SSPE are not contagious. SSPE has
been very uncommon in the United States since the initiation of the routine measles
immunization.

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How can measles be prevented?

Measles is effectively prevented by the routine administration of the measles vaccine,
usually given as Measles-Mumps-Rubella (MMR) vaccines to all children. This vaccine
is recommended beginning at 12 months of age. A single dose of the measles vaccine
results in protection of approximately 95% of children. To ensure that all children
are immunized, a second dose of MMR is recommended at four to six years of age;
however, it can be given to children at any age as soon as one month after the first
dose.

Many states require two doses of the measles vaccine for school entry, and many
colleges and universities require evidence of two doses of the measles vaccine for
admission. It is not a problem if an additional dose of the measles vaccine is given
in addition to the two recommended doses.

The spread of measles can be prevented by minimizing exposure to children who have
symptoms of the disease, and by good handwashing after exposure to the disease.

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What research is being done?

Because measles is now extremely uncommon, and because the vaccine is extremely
safe and effective in preventing measles, there is not much research on measles
currently being conducted. There is some research being performed on the long-term
immunity of the measles vaccine to confirm that it does provide lifelong immunity.

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About the Authors

Hal Jenson, M.D.

Dr. Jenson graduated from George Washington University School of Medicine in Washington,
DC.

He also completed a residency in pediatrics at the Rainbow Babies and Children’s
Hospital of Case Western Reserve University in Cleveland, Ohio, and a fellowship
in pediatric infectious diseases and epidemiology at Yale University School of Medicine.

Dr. Jenson has an active research program on the biology of Epstein-Barr virus and
other human and non-human primate herpes viruses.

He is active in the general pediatric and infectious diseases teaching and clinical
activities of his Department and Division, is a co-editor of Nelson Textbook of
Pediatrics and of Pediatric Infectious Diseases: Principles and Practice, and authors
the book Pocket Guide to Vaccination and Prophylaxis.

Charles T. Leach, M.D.

Dr. Leach received his medical degree at the University of Utah School of Medicine
and completed his pediatrics residency as well as a fellowship in pediatric infectious
diseases at UCLA.

He is currently Associate Professor and Director of Research in the Department of
Pediatrics at the University of Texas Health Science Center at San Antonio.

Dr. Leach conducts scientific research in the areas of herpes virus infections,
pediatric AIDS, and infectious diseases among residents of the Texas-Mexico border.

Copyright 2012 Hal B. Jenson, M.D., All Rights Reserved