Measles (ME-zuls) is a viral respiratory system * infection that is best known for the rash of large, flat, red blotches that appear on the arms, face, neck, and body.
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* respiratory system, or respiratory tract, includes the nose, mouth, throat, and lungs. It is the pathway through which air and gases are transported down into the lungs and back out of the body.
* vaccine (vak-SEEN) is a preparation of killed or weakened germs, or a part of a germ or product it produces, given to prevent or lessen the severity of the disease that can result if a person is exposed to the germ itself. Use of vaccines for this purpose is called immunization.
What Is Measles?
Measles, also known as rubeola (roo-be-O-luh), is a highly contagious viral infection caused by the measles virus. Most people are familiar with its most recognized feature: a near full-body rash of red blotches. In fact, measles is primarily an infection of the respiratory system. The disease has been diagnosed throughout the world, and before a vaccine * was available it commonly appeared in the United States in springtime epidemics * every few years. In the United States, 1 to 2 deaths occur for every 1,000 cases of measles. In developing countries, the fatality rate can be as high as 1 in every 4 people who contract the disease. Most deaths from measles in the United States are caused by pneumonia (nu-MO-nyah, inflammation of the lung), either from the measles virus itself or from a bacterial infection that arises as a complication of measles.
How Common Is Measles?
Before the introduction of the measles vaccine in 1963, approximately 500,000 reported cases of measles and 500 deaths occurred in the United States each year. Since the start of measles vaccination programs, though, infection rates have dropped by more than 98 percent, and epidemics have all but disappeared. According to the U.S. Centers for Disease Control and Prevention, between 1993 and 2001 there were fewer than 500 cases of measles diagnosed each year (in 2000 there was an all-time low of 86 cases). However, an earlier resurgence of measles between 1989 and 1991 led to more than 55,000 diagnosed cases and 123 deaths. This epidemic arose because many children were not being vaccinated.
By contrast, the effect of measles in the developing world remains staggering. The disease accounted for about 777,000 deaths in 2001. Limited access to the vaccine is the primary reason that developing countries continue to see huge numbers of measles cases. Immigrants to the United States who have not received the vaccine in their native countries account for many of the cases of the disease that occur in the United States.
Cases of measles infection rose dramatically during the years 1989 to 1991 in the United States and other countries. Nearly half of the U.S. patients were unvaccinated preschool children living in urban areas. The epidemic began because of a lapse in measles vaccinations and public education. Many people were unaware that measles was still a threat, because years of public vaccinations had controlled the infection; some were afraid of adverse reactions to the vaccine itself. Emergency vaccinations eventually contained the epidemic, but the outbreak revealed the persistence of a virus that many believed was no longer a cause for concern.
* epidemics (eh-pih-DEH-miks) are outbreaks of disease, especially infectious disease, in which the number of cases suddenly becomes far greater than usual. Usually, epidemics are outbreaks of diseases in specific regions, whereas worldwide epidemics are called pandemics.
The Spread of Measles
Historically, infectious diseases have been powerful players on the world stage. They have toppled kingdoms, swept through countries with devastating results, and altered world economies and religions. Measles traveled around the globe with European adventurers and explorers. The disease cut a swath through the inhabitants of the Pacific Islands and the Americas (North America, South America, and Central America). When the Spanish conquistadors Hernán Cortés (1485-1547) and Francisco Pizarro (ca. 1475—1541) arrived in the Americas, they unknowingly carried with them measles and smallpox, which resulted in the death of an estimated one-third of the native populations.
How Does Measles Spread?
Measles is highly contagious and can spread quickly among people who have not been immunized against it. The measles virus spreads by direct contact with an infected person or by breathing in tiny drops of fluid sent into the air when the person sneezes, coughs, or laughs. A cough or sneeze releases thousands of microscopic particles that contain the virus. They can stay in the air, able to infect people, for up to 2
What Are the Signs and Symptoms?
After a person has been exposed to the virus, there is an incubation period that averages 10 to 12 days. The first symptoms include fever, runny nose, cough, and reddened eyes that are sensitive to light. Koplik spots, a unique sign of measles, break out 1 to 2 days before the rash begins and usually are gone by the time it appears; they are bluish-white dots found on the inside of the cheeks and other places on the mucous membranes (moist linings) in the mouth.
The measles rash typically begins on the forehead and extends down across the face, neck, and body. It generally takes several days for the rash to travel from head to toes. The red blotches often spread out and join, completely covering the skin, especially on the face and shoulders. Once the rash appears, 2 to 4 days after the onset of illness, the fever rises and may peak at 104 to 105 degrees Fahrenheit. During this time, the patient looks and feels very ill. Symptoms improve soon after the rash has traveled down to the legs and feet, usually accompanied by a rapid drop in temperature. The rash fades along the same path that it appeared, beginning at the forehead and working its way down. As the rash disappears, the skin may temporarily look brown, dry, and flaky. Other symptoms of measles include loss of appetite, vomiting, and diarrhea (dye-uh-REE-uh), especially in young children. Hemorrhagic (heh-muh-RAH-jik) measles is a rare and serious form of the disease characterized by hemorrhaging (uncontrolled or abnormal bleeding), high fever, seizures * , and delirium * .
How Do Doctors Make the Diagnosis?
Measles can be diagnosed by asking a patient about symptoms and performing a physical examination. If there is a question about the diagnosis or if it is necessary to confirm a suspected case of measles, blood tests can determine whether antibodies * to the virus have developed in the body.
* seizures (SEE-zhurs) are sudden bursts of disorganized electrical activity that interrupt the normal functioning of the brain, often leading to uncontrolled movements in the body and sometimes a temporary change in consciousness.
* delirium (dih-LEER-e-um) is a condition in which a person is confused, is unable to think clearly, and has a reduced level of consciousness.
* antibodies (AN-tih-bah-deez) are protein molecules produced by the body's immune system to help fight specific infections caused by microorganisms, such as bacteria and viruses.
* dehydration (dee-hi-DRAY-shun) is a condition in which the body is depleted of water.
* intravenous (in-tra-VEE-nus) fluids are fluids injected directly into a vein.
What Is the Treatment for Measles?
Because measles is caused by a virus, treatment generally is aimed at keeping the patient comfortable until the infection runs its course. The high fever and sweating that accompany measles raise the risk of dehydration * , so patients should have plenty of rest and fluids. Taking vitamin A may aid recovery in some cases, especially among children with poor nutrition. Serious cases may require a hospital stay and intravenous fluids * . Antibiotics are given when bacterial infections (such as ear infections or pneumonia) develop as complications of the disease.
What to Expect
Measles generally lasts between 10 and 14 days from the onset of symptoms through the fading of the rash. Ear infections, croup * , and pneumonia sometimes accompany measles. Less commonly, inflammation of the brain (known as encephalitis, en-seh-fuh-LYE-tis) or inflammation of the heart muscle (known as myocarditis, my-oh-kar-DYE-tis) can occur. Subacute sclerosing panencephalitis * (SSPE), a type of encephalitis, is an extremely rare late complication of lasting measles virus infection that can cause gradual loss of brain function. SSPE may occur months, years, or even decades after measles infection, but it is almost never seen in the United States, as a result of widespread use of the measles vaccine. If a pregnant woman contracts measles, the infection can harm her developing baby, leading to miscarriage * , premature labor * , or low birth weight.
How Can Measles Be Prevented?
The best protection against measles is immunization. The vaccine usually is given as part of a combined measles-mumps-rubella (MMR) vaccine that children typically receive twice in their lives. The first round is given when an infant is 12 to 15 months old and the second when the child is ready to start school, at 4 to 5 years old. Children also may receive the second vaccine when they are 11 or 12 years old, if they do not receive it earlier. Because about 5 percent of people do not develop protective antibodies after the first MMR vaccine, the second dose offers better protection against infection. If someone comes into contact with a person who has measles and then is vaccinated within 3 days of that exposure, the vaccine may prevent or lessen the severity of a case of measles. Immune globulin * can have the same result if it is given within 6 days of exposure to the virus.
* croup (KROOP) is an infection involving the trachea (windpipe) and larynx (voice box) that typically occurs in childhood. It causes inflammation and narrowing of the upper airway, sometimes making it difficult to breathe. The characteristic symptom is a barking cough.
* subacute sclerosing panencephalitis (sub-uh-KYOOT skluh-RO-sing pan-en-seh-fuh-LYE-tis), or SSPE, is a chronic brain disease of children and adolescents that occurs months or years after having had measles; it causes convulsions, movement problems, and mental retardation and is usually fatal.
* miscarriage is the ending of a pregnancy through the death of the embryo or fetus before birth.
* premature labor is labor (the birth process) that begins too early, before the fetus has developed fully in the womb.
* immune globulin (ih-MYOON GLAH-byoo-lin), also called gamma globulin, is the protein material that contains antibodies.
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