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