Measles is a highly contagious disease of the upper respiratory tract accompanied by fever and a characteristic reddish rash that spreads over the entire body. The name of the disease dates back to fourteenth-century English and means “spot.”
Measles is a disease that has been known in Europe and the Middle East for centuries. The earliest description of it comes from a Persian doctor in the tenth century named Rhazes (860–932). Measles is caused by a
virus in the same group of viruses as the mumps virus. It is highly contagious and is usually spread by contact with droplets or fluids from an infected person's nose or mouth. Ninety percent of people who have not been immunized will come down with measles if they share a household with someone who has it. In countries with temperate climates, people are most likely to get measles in late winter or spring.
The disease is preceded by a prodrome or group of warning symptoms, including tiredness, fever, and loss of appetite. After an incubation period of eight to twelve days, the patient develops a higher fever of about 104°F (40°C) accompanied by an inflammation of the lining of the eyelids, sneezing, and coughing. The person can spread the disease for about two days before these symptoms appear. The characteristic rash of measles appears next, lasting for about six days. The person can continue to spread the disease for about four days after the rash appears.
Most children will feel better about ten days after the beginning of symptoms, although about one child in ten will develop an ear infection after the rash fades.
Measles is now a rare disease in the United States, with fewer than 100 cases in an average year. In November 2002 measles was defined as no
longer endemic (prevalent) in the United States, meaning that infected visitors to the country are the primary source of new cases. After a vaccine against measles was available in 1963, the number of new cases in the United States dropped by 99 percent by 1993. In 1997 the rate of new cases was only one case for every two million people. The last major outbreak of measles in the United States occurred from 1989 to 1991; it caused 55,000 cases and 123 deaths. In 2006 there were forty-six reported cases of measles in the United States.
In the developing world, however, measles is still a major cause of death. According to the World Health Organization (WHO), there are about thirty million new cases of measles every year, most of these being reported in Africa. Measles causes about 880,000 deaths each year, mostly in Africa and Southeast Asia. The most vulnerable patients are infants between four and twelve months of age and children infected with the HIV virus.
Measles affects all races equally. Males and females are equally likely to get measles, but girls in developing countries are more likely than boys to die from the disease. Adults who get measles are more likely than children to develop serious complications.
People at greatest risk for complications include those with weakened immune systems, including HIV infection and leukemia; those who are malnourished; those with a vitamin A deficiency; and pregnant women.
Measles and Native Americans
Measles was a major cause of death among Native Americans after the early 1500s, when Europeans first came to North and Central America. Major epidemics of measles occurred in Mexico and what is now upstate New York in the 1500s; in New England in the 1600s; in New England, the Great Lakes region, the Southwest, Texas, and the Great Plains in the 1700s; and northern Mexico and the Pacific Northwest in the 1800s. In some areas nine of every ten Native Americans died during these epidemics.
Doctors have studied why Native Americans were so vulnerable to measles. Some believed it was because Native Americans had never been exposed to the disease before 1500. Another theory was that the measles virus was much stronger in the 1500s to 1800s than it is today, and that the Native Americans were overwhelmed by a more powerful infection. In the 1970s, however, Dr. Francis Black (1925– 2007), who helped develop the first measles vaccine in humans, began studying the genetic factors affecting the immune systems of the Indians in the Amazon rain forest.
Black discovered that Native Americans were more vulnerable to measles due to a relative lack of variety in their immune systems. In some parts of Africa, for example, some 200 different immune system profiles exist in the general population. So, if one person gets a viral disease, it may not spread rapidly among others because they may be resistant to the virus. Native Americans have only three different immune system profiles. This means that a disease like measles can spread much more quickly among them and cause widespread loss of life.
The cause of measles is a highly contagious virus spread by droplets from the coughing
and sneezing of an infected person. The measles virus enters the passages of the nose and upper throat until it reaches the airway and its branches into the lungs. The virus multiplies in the moist tissue lining the airway and infects the local lymph nodes, causing them to swell. It is then carried to other lymph nodes, the urinary tract, the blood vessels, the tissues lining the eyelid, and the central nervous system.
After the initial incubation period, the patient develops an itchy rash that starts on the face and head and spreads downward to cover the entire body. The rash looks like large reddish blotches that flow into each other. It eventually turns brown and looks like a stain or discoloration of the skin. The rash fades completely in about a week.
Infants and small children may also develop diarrhea and vomiting with the measles.
The diagnosis of measles is usually made on the basis of a fever lasting for three days and the appearance of reddish spots with white centers on the lining of the cheeks. These spots are called Koplik spots, named for an American pediatrician who first described them in 1896. They often appear inside the mouth about two days before the characteristic rash of measles and remain for about two days after the rash erupts.
Because measles is now rare in the United States, the doctor may take a sample of blood or nasal secretions to be tested to confirm the diagnosis.
If the doctor is concerned that the patient may have developed pneumonia as a complication of the measles, he or she may order a chest x ray. A spinal tap may be ordered if the patient has symptoms of encephalitis.
Treatment of measles usually consists simply of staying home to avoid spreading the disease to others, resting in bed, and drinking lots of clear fluids. Acetaminophen can be taken to bring down the fever; children should not be given aspirin, however, because of the risk of Reye syndrome.
Pregnant women, infants younger than six to nine months, and people with weakened immune systems are given a shot of immune globulin, or antibodies against the measles virus. A patient who develops an ear infection or shows signs of pneumonia will be treated with an antibiotic. Young children who become severely ill with measles may be given a large dose of vitamin A.
The prognosis for most patients with measles is complete recovery after ten days to two weeks. About one person in ten will develop an ear infection, one in fifteen will develop pneumonia, and one in 1,000 will develop encephalitis (inflammation of the brain). Some patients will also develop laryngitis or bronchitis as complications of measles. Pregnant women who get measles may lose the baby, go into childbirth too early, or have a baby with an abnormally low birth weight.
The death rate from measles in otherwise healthy people in developed countries is low, about one death per 1,000 cases of the disease. In developing countries, however, the death rate may be as high as 10 percent of cases. People with weakened immune systems have a death rate approaching 30 percent.
Measles can be prevented in 95 percent of people by immunization with the measles-mumps-rubella or MMR vaccine. Giving two doses of the vaccine is usually enough to prevent measles in the 5 percent who do not develop immunity with the first dose. The vaccine is usually given to children twice before they start school, the first dose at twelve to fifteen months of age and the second dose between four and six years. Infants are not usually given the vaccine because they are protected for the first six months of life if the mother was immunized.
Most people have no side effects from the MMR vaccine. About 10 percent will have a mild fever within a week of the shot, however, and about 5 percent will develop a skin rash. People who have an immune system disorder or are being treated for cancer should talk to their doctor before getting a dose of the MMR vaccine.
In recent years there have been concerns raised about a possible connection between the MMR vaccine and autism. Studies carried out by the American Academy of Pediatrics and the Institute of Medicine,
however, have shown that the vaccine does not cause autism. The reason that some people thought that it might is because autism is often identified in young children at about the same time that the first dose of the MMR vaccine is usually given. Children are at much greater danger from getting the measles than from any side effect of the vaccine.
It is possible that measles will disappear entirely in the future, as smallpox already has and as polio is likely to do. In 2001 the American Red Cross, the World Health Organization, the Centers for Disease Control and Prevention (CDC), and other public health organizations formed the Measles Initiative, whose goal was to immunize 200 million children in Africa against measles by 2006. By November 2005, the program reported that deaths from measles in Africa had already dropped by 60 percent.
SEE ALSO Autism; Ear infection; Encephalitis; Laryngitis; Pneumonia; Reye syndrome
WORDS TO KNOW
Encephalitis : Inflammation of the brain.
Endemic : A term applied to a disease that maintains itself in a particular area without reinforcement from outside sources of infection.
Koplik spots : Small reddish spots with white centers seen on the tissues lining the cheeks in early-stage measles.
Prodrome : A period before the acute phase of a disease when the patient has some characteristic warning symptoms.
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Mann, Charles C. “1491.” Atlantic Monthly, March 2002. Available online at http://www.theatlantic.com/doc/200203/mann (accessed April 24, 2008). This is an article about the vulnerability of Native Americans to measles and other diseases brought to the Americas by Europeans.
Smith, Stephen. “Measles Outbreak Shows a Global Threat.” Boston Globe, June 10, 2006. Available online at http://www.boston.com/yourlife/health/diseases/articles/2006/06/10/measles_outbreak_shows_a_global_threat/?page=full (accessed April 23, 2008). This is an article about the rapid spread of measles among unimmunized people in the United States due to globalization.
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