Measles is a highly contagious infection of the respiratory system caused by the measles virus, which is found worldwide. The virus multiplies in cells of the respiratory tract in infected persons and is released into fluids of the nose, throat and mouth.
Measles is very common in developing countries and an estimated 43 million cases occur yearly, with more than 1 million deaths. In the United States, about 350 cases are reported each year. Most, if not all, of these cases are in people who became infected in other countries.
Although measles continues to be a problem in developing countries, U.S. measles cases have been decreasing since 1993. The decrease can be attributed to: 1) increased immunization coverage, 2) the use of a two-dose vaccine strategy for children, and 3) programs to eliminate measles in Mexico and Central and South America. Measles can be prevented by immunization. About 95% of vaccinated persons are protected with one dose, and practically everyone is protected with two doses.
It is clear that there are risks associated with the various measles vaccines and the debate over whether they should be given to children rages on.
People get measles when they breathe in tiny droplets that contain the virus. The virus attaches to the lining of the airways, multiplies, and causes disease. People can also be infected by direct contact with fluid from the nose or mouth of an infected person. An uninfected person can get measles simply by breathing the air in a room where an infected person has been. The virus can live in the air for 2 hours after an infected person leaves a room. Infected persons are usually infectious to others even before symptoms appear.
Persons who have not been immunized against measles are the main risk group. Infants are generally protected from measles for 6-8 months after birth, due to immunity that was passed on by their mothers. Older children usually receive measles immunization according to state and school health regulations in the MMR vaccine. Outbreaks of measles are currently occurring most often on college campuses, among young persons who have not been adequately immunized against measles or whose immunity has decreased since childhood.
Measles symptoms usually show up in two stages. The first stage begins with a runny nose, cough, and a slight fever. As the infection progresses, the person's eyes become red and sensitive to light, and the fever rises. The second stage begins after 3-7 days. The fever reaches 103°F-105°F (39.5°C-40.6°C), and a red blotchy rash appears. The rash usually starts on the face and then spreads to the chest, back, and arms and legs, including the palms and soles of the feet. The rash lasts for 4-7 days. Small white spots might also appear on the gums and inside of the cheeks.
Measles can usually be diagnosed by symptoms. A blood test can confirm the diagnosis.
There is no specific treatment for measles. If measles is suspected, a health-care provider should be contacted. The health-care provider can confirm the diagnosis and provide home-care instructions to relieve the discomfort of the symptoms.
Pneumonia occurs in up to 6% of reported measles cases and accounts for 60% of deaths from measles. Encephalitis, middle ear infections and convulsions can also occur. The risk of complications varies with age. Infants under age 2 years and adults over age 20 have a 20% to 30% chance of complications, often requiring hospitalization. School-age children have a 3% to 5% chance of serious complications.