Measles is a respiratory disease caused by a virus (also called measles) that is transmitted by infected droplets in the air. The disease is also called rubeola. Measles virus normally grows in the cells that line the back of the throat and lungs.
Measles is highly contagious and can spread to others from four days before to four days after the rash appears. Measles is so contagious that if one person has it, 90 percent of the people close to that person who are not vaccinated will also become infected with the measles virus.
The virus lives in mucus in the nose and throat of an infected person. When that person sneezes or coughs, droplets spray into the air. The droplets can get into other people’s noses or throats when they breathe or put their fingers in their mouth or nose after touching an infected surface. The virus can live on infected surfaces for up to two hours and spreads so easily that people who are not immune will probably get it when they come close to someone who is infected.
Measles is a disease of humans; measles virus is not spread by any other animal species.
The symptoms of measles generally begin about seven to 14 days after a person is infected and include:
• Blotchy rash
• Feeling run down, achy
• Red, watery eyes
• Runny nose
• Tiny white spots with bluish-white centers found inside the mouth
A typical case of measles begins with mild to moderate fever, cough, runny nose, red eyes and sore throat. Two or three days after symptoms begin, tiny white spots may appear inside the mouth.
Three to five days after the start of symptoms, a red or reddish-brown rash appears. The rash usually begins on a person’s face at the hairline and spreads downward. When the rash appears, a person’s fever may spike to more than 104 degrees Fahrenheit. After a few days, the fever usually subsides and the rash fades.
About 30 percent of measles cases develop one or more complications, including:
• Pneumonia, which is the complication that is most often the cause of death in young children.
• Ear infections occur in about one in 10 measles cases and permanent loss of hearing can result.
• Diarrhea is reported in about 8 percent of cases.
These complications are more common among children under 5 years of age and adults older than 20 years old.
Even in previously healthy children, measles can be a serious illness requiring hospitalization. As many as one out of every 20 children with measles gets pneumonia, and about one child in every 1,000 who get measles will develop encephalitis (an inflammation of the brain that can lead to convulsions, and can leave the child deaf or mentally ill). For every 1,000 children who get measles, one or two will die. Measles also can make a pregnant woman have a miscarriage, give birth prematurely, or have a low-birth-weight baby.
In developing countries, where malnutrition and vitamin A deficiency are common, measles has been known to kill as many as one out of four people. It is the leading cause of blindness among African children. Measles kills almost 1 million children in the world each year.
Measles is very rare in countries and regions of the world that are able to keep vaccination coverage high. In North and South America, Finland, and some other areas, endemic measles transmission is considered to have been interrupted through vaccination. There are still sporadic cases of measles in the United States because visitors from other countries or US citizens traveling abroad can become infected before or during travel and spread the infection to unvaccinated or unprotected persons.
Worldwide, there are estimated to be 20 million cases and 164,000 deaths each year. More than half of the deaths occur in India. For more information on measles in the United States and worldwide, visit the CDC’s Global Elimination page.
Measles can be prevented by the combination MMR (measles, mumps and rubella) vaccine. However, measles is still common in other countries. The virus is highly contagious and can spread rapidly in areas where vaccination is not widespread.
For more information, visit the CDC’s Measles Vaccination page.