Measles is an infection caused by the genus of viruses called Morbillivirus that displays a characteristic skin rash known as an exanthem. Measles is also sometimes called rubeola, 5-day measles, red measles, or hard measles. The second type of measles is called the rubella virus or German measles, also known as 3-day measles.
One of the earliest known written descriptions of measles as a disease was provided by an Arab physician in the ninth century who described the differences between measles and smallpox in his medical notes. Later, Scottish physician Francis Home demonstrated in 1757 that measles was caused by an infectious agent present in the blood of patients. In 1954, the virus that causes measles was isolated in Boston, Massachusetts, by John F. Enders and Thomas C. Peebles. Before measles vaccine was developed in 1963, nearly all children got measles by the time they were 15 years old. Each year prior to 1963, about 450–500 people died because of measles, 48,000 were hospitalized, 7,000 had seizures, and about 1,000 suffered permanent brain damage or deafness.
Measles infections appear all over the world. Prior to the current effective immunization program, large-scale measles outbreaks occurred on a two to three-year cycle, usually in the winter and spring. Smaller outbreaks occurred during the off-years. Babies up to about eight months old are usually protected from contracting measles by immune cells they receive from their mothers in the uterus. Once people have had a measles infection, they are immune to the disease and can never get it again.
As a result of widespread immunization, the measles virus does not circulate in the United States. All reported cases of measles in the United States have been brought in from other countries, usually Europe and Asia. Travelers leaving the United States should have had routine vaccinations against measles; however, an increasingly active anti-vaccination movement in the United States and Europe has encouraged many parents to skip this vaccination, leaving a segment of the public vulnerable to the disease. In 2017, there were 118 cases of measles in the United States across 15 states and the District of Columbia. In Europe in 2017, there were a reported 21,315 cases of measles with 35 deaths. Worldwide, the World Health Organization reported 89,780 measles deaths in 2016.
Although measles is usually considered a childhood disease, it can be contracted at any age by a person who never before had the disease or been vaccinated. Unvaccinated individuals are 22 times more likely to get measles than are those who have had two measles vaccinations, usually given as measles, mumps, and rubella vaccine (MMR). People born before 1957 are assumed to be immune to the disease without vaccination because they would have contracted it naturally in childhood.
Measles is an extremely contagious infection, spread through the tiny droplets that may spray into the air when an individual carrying the virus sneezes or coughs. About 90% of nonimmunized people exposed to the virus will become infected and develop the illness. Once people are infected with the virus, it takes about 7–18 days before they actually become ill. The most contagious time is the three to five days before symptoms begin through about four days after the characteristic measles rash has begun to appear.
The early signs of measles infection are fever, extremely runny nose, red eyes, and a cough. A few days later, a rash appears in the mouth, particularly on the mucous membrane lining the cheeks. This rash consists of tiny white dots (like grains of salt or sand) on a reddish bump. These are called Koplik's spots and are unique to measles infection. The throat becomes red, swollen, and sore.
Many patients (about 5–15%) develop other complications. Bacterial infections, such as ear infections, sinus infections, and pneumonia are common, especially in children. Other viral infections may also strike patients. These include croup, bronchitis, laryngitis, or viral pneumonia. Inflammation of the liver, appendix, intestine, or lymph nodes within the abdomen may cause other complications. Rarely, inflammations of the heart or kidneys, a drop in platelet count (causing episodes of difficult-to-control bleeding), or reactivation of an old tuberculosis infection can occur.
An extremely serious complication of measles infection is swelling of the brain. Called encephalitis, this condition can occur up to several weeks after the basic measles symptoms have resolved. About one out of every thousand patients develops this complication, and about 10–15% of these patients die. Symptoms include fever, headache, sleepiness, seizures, and coma. Long-term problems following recovery from measles encephalitis may include seizures and permanent developmental delays.
A very rare complication of measles can occur up to ten years following the initial infection. Called subacute sclerosing panencephalitis, this condition is a slowly progressing, smoldering swelling and destruction of the entire brain. It is most common among people who had measles infection prior to the age of two years. Symptoms include changes in personality, decreased intelligence with accompanying school problems, decreased coordination, involuntary jerks, and movements of the body. The disease progresses so that affected individuals become increasingly dependent, ultimately becoming bedridden and unaware of their surroundings. Blindness may develop, and the temperature may spike (rise rapidly) and fall unpredictably as the brain structures responsible for temperature regulation are affected. Death is inevitable.
Measles during pregnancy is a serious disease, leading to increased risk of a miscarriage or stillbirth. In addition, the mother's illness may progress to pneumonia.
People who do not receive the vaccine for measles are much more likely to develop the disease. Unvaccinated people traveling to developing countries, where measles is more common, are also at higher risk of catching the disease, and people who do not have enough vitamin A in their diets are more likely to contract measles and to have more severe symptoms.
Measles infection is almost always diagnosed based on its characteristic symptoms, including Koplik's spots, and a rash which spreads from central body structures out toward the arms and legs. If there is any doubt as to the diagnosis, then a specimen of body fluids (mucus, urine) can be collected and combined with fluorescent-tagged measles virus antibodies. Antibodies are produced by the body's immune cells that can recognize and bind to markers (antigens) on the outside of specific organisms, in this case the measles virus. Once the fluorescent antibodies have attached themselves to the measles antigens in the specimen, the specimen can be viewed under a special microscope to verify the presence of measles virus.
There are no treatments available to stop measles infection. Treatment is primarily aimed at helping the patient to be as comfortable as possible and watching carefully so that antibiotics can be started promptly if a bacterial infection develops. Fever and discomfort can be treated with acetaminophen. Children with measles should never be given aspirin, as this has caused the fatal disease Reye's syndrome in the past. A cool-mist vaporizer may help decrease the cough. Patients should be given a lot of liquids to drink, to avoid dehydration from the fever.
Botanical immune enhancement (with echinacea, for example) can assist the body in working through this viral infection. Homeopathic support also can be effective throughout the course of the illness. Specific alternative treatments to soothe patients with measles include the Chinese herbs bupleurum (Bupleurum chinense) and peppermint (Mentha piperita), as well as a preparation made from empty cicada (Cryptotympana atrata) shells. The itchiness of the rash can be relieved with witch hazel (Hamamelis virginiana), chickweed (Stellaria media), or oatmeal baths. The eyes can be soothed with an eyewash made from the herb eyebright (Euphrasia officinalis). Practitioners of ayurvedic medicine recommend ginger or clove tea.
The prognosis for an otherwise healthy, well-nourished child who contracts measles is usually quite good. In developing countries, however, death rates may reach 15–25%. Adolescents and adults usually have a more difficult course. Women who contract the disease while pregnant may give birth to a baby with hearing impairment. Although only 1 in 1,000 patients with measles develops encephalitis, 10%–15% of those who do will die, and about another 25% will be left with permanent brain damage.
Measles is a highly preventable infection. An effective vaccine (MMR) exists, made of live measles viruses, which have been treated and weakened so that they cannot cause the disease. The important markers on the viruses are intact, however, which causes an individual's immune system to react. Immune cells called antibodies are produced, which in the event of a future infection with measles virus will quickly recognize the organism and kill it. The vaccine also contains weakened viruses that protect against mumps and rubella (German measles). A vaccine that protects against only measles was not available in the United States as of 2018.
MMR vaccine usually is given at about 15 months of age. Prior to that age, the baby's immune system is not mature enough to initiate a reaction strong enough to insure long-term protection from the virus. A repeat injection should be given at about 4–6 years of age. Outbreaks of the virus brought into the United States from travelers have occurred among unimmunized or incompletely immunized children.
Measles vaccine should not be given to a pregnant woman, however, despite the seriousness of gestational measles. The reason for not giving this vaccine during pregnancy is the risk of transmitting measles to the unborn child.
In the past, it was claimed by anti-vaccinationists that the combined vaccine for measles, mumps, and rubella (MMR) caused autism in some children. However, it has conclusively been shown by multiple researchers in multiple countries that this claim is false. Autism is now thought to be caused by the interaction of not completely understood genetic and environmental exposures.
Only humans get measles. There is no animal reservoir to keep the virus in circulation. This makes measles a good candidate for worldwide eradication. In the United States, measles was declared eliminated in 2000 due to high vaccination coverage and effective public health response. That means measles no longer naturally occurs in the United States. However, travelers who have not been vaccinated continue to bring a small number of cases into the United States each year. This occurs because people are contagious before they show any symptoms of the disease. The risk is increased when parents, feeling measles is no longer a threat to their children's health, refuse the MMR vaccine. These children are then at risk for acquiring the disease either from contagious travelers coming into the country or by traveling to countries where measles continues to exist. Measles is a reportable disease, meaning doctors must inform public health authorities if they diagnose a case.
See also Communicable diseases ; Vaccination .
Davidson, Tish. Vaccines: History, Science, and Issues. Santa Barbara, CA: Greenhaven Press, 2017.
Gehlbach, Stephen H. American Plagues: Lessons from Our Battles with Disease. Lanham, MD: Rowman & Littlefield, 2016.
MacMillan, Amanda, and David Johnson. “Measles Cases Are Rising: Here Are the States Where It's Becoming More Common.” Time, October 4, 2017. http://time.com/4968993/measles-vaccination (accessed April 22, 2018).
McNeil, Donald. “Measles Cases in Europe Quadrupled in 2017.” New York Times, February 23, 2018. https://www.nytimes.com/2018/02/23/health/measles-europe.html accessed April 22, 2018).
Chen, Selina. “Measles.” Medscape.com . https://emedicine.medscape.com/article/966220-overview (accessed April 22, 2018).
U.S. Centers for Disease Control and Prevention. “Measles (Rubeola).” https://www.cdc.gov/measles/index.html (accessed April 22, 2018).
U.S. National Library of Medicine. “Measles.” MedlinePlus. https://medlineplus.gov/measles.html (accessed April 22, 2018).
World Health Organization. “Measles.” http://www.who.int/mediacentre/factsheets/fs286/en (accessed April 22, 2018).
U.S. Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA, 30329-4027, (404) 639-3534, (800) 232-4636; TTY: 888-232-6348, http://www.cdc.gov .
World Health Organization, Avenue Appia 20, 1211 Geneva 27, Switzerland, +2241 791 21 11, Fax: +2241 791 31 11, email@example.com, http://www.who.int .
Rosalyn Carson-DeWitt, MD
Rebecca J. Frey, PhD
Revised by Tish Davidson, AM