Overview

Measles is a childhood infection caused by a virus. Once quite common, measles can now almost always be prevented with a vaccine.

Also called rubeola, measles can be serious and even fatal for small children. While death rates have been falling worldwide as more children receive the measles vaccine, the disease still kills more than 100,000 people a year, most under the age of 5.

As a result of high vaccination rates in general, measles hasn't been widespread in the United States for more than a decade. The United States averaged about 60 cases of measles a year from 2000 to 2010, but the average number of cases jumped to 205 a year in recent years. Most of these cases originate outside the country and occurred in people who were unvaccinated or who didn't know whether or not they had been vaccinated.

Symptoms

Measles signs and symptoms appear around 10 to 14 days after exposure to the virus. Signs and symptoms of measles typically include:

  • Fever
  • Dry cough
  • Runny nose
  • Sore throat
  • Inflamed eyes (conjunctivitis)
  • Tiny white spots with bluish-white centers on a red background found inside the mouth on the inner lining of the cheek — also called Koplik's spots
  • A skin rash made up of large, flat blotches that often flow into one another

The infection occurs in sequential stages over a period of two to three weeks.

  • Infection and incubation. For the first 10 to 14 days after you're infected, the measles virus incubates. You have no signs or symptoms of measles during this time.
  • Nonspecific signs and symptoms. Measles typically begins with a mild to moderate fever, often accompanied by a persistent cough, runny nose, inflamed eyes (conjunctivitis) and sore throat. This relatively mild illness may last two or three days.
  • Acute illness and rash. The rash consists of small red spots, some of which are slightly raised. Spots and bumps in tight clusters give the skin a splotchy red appearance. The face breaks out first.

    Over the next few days, the rash spreads down the arms and trunk, then over the thighs, lower legs and feet. At the same time, the fever rises sharply, often as high as 104 to 105.8 F (40 to 41 C). The measles rash gradually recedes, fading first from the face and last from the thighs and feet.

  • Communicable period. A person with measles can spread the virus to others for about eight days, starting four days before the rash appears and ending when the rash has been present for four days.

When to see a doctor

Call your doctor if you think you or your child may have been exposed to measles or if you or your child has a rash resembling measles.

Review your family's immunization records with your doctor, especially before starting elementary school, before college and before international travel.

Causes

Measles is a highly contagious illness caused by a virus that replicates in the nose and throat of an infected child or adult. Then, when someone with measles coughs, sneezes or talks, infected droplets spray into the air, where other people can inhale them.

The infected droplets may also land on a surface, where they remain active and contagious for several hours. You can contract the virus by putting your fingers in your mouth or nose or rubbing your eyes after touching the infected surface.

About 90 percent of susceptible people who are exposed to someone with the virus will be infected.

Risk factors

Risk factors for measles include:

  • Being unvaccinated. If you haven't received the vaccine for measles, you're much more likely to develop the disease.
  • Traveling internationally. If you travel to developing countries, where measles is more common, you're at higher risk of catching the disease.
  • Having a vitamin A deficiency. If you don't have enough vitamin A in your diet, you're more likely to have more-severe symptoms and complications.

Complications

Complications of measles may include:

  • Ear infection. One of the most common complications of measles is a bacterial ear infection.
  • Bronchitis, laryngitis or croup. Measles may lead to inflammation of your voice box (larynx) or inflammation of the inner walls that line the main air passageways of your lungs (bronchial tubes).
  • Pneumonia. Pneumonia is a common complication of measles. People with compromised immune systems can develop an especially dangerous variety of pneumonia that is sometimes fatal.
  • Encephalitis. About 1 in 1,000 people with measles develops a complication called encephalitis. Encephalitis may occur right after measles, or it might not occur until months later.
  • Pregnancy problems. If you're pregnant, you need to take special care to avoid measles because the disease can cause preterm labor, low birth weight and maternal death.

Prevention

If someone in your household has measles, take these precautions to protect vulnerable family and friends:

  • Isolation. Because measles is highly contagious from about four days before to four days after the rash breaks out, people with measles shouldn't return to activities in which they interact with other people during this period.

    It may also be necessary to keep nonimmunized people — siblings, for example — away from the infected person.

  • Vaccinate. Be sure that anyone who's at risk of getting the measles who hasn't been fully vaccinated receives the measles vaccine as soon as possible. This includes anyone born after 1957 who hasn't been vaccinated, as well as infants older than 6 months.

    The first dose for infants is usually given between 12 and 15 months, with the second dose typically given between ages four and six years. If you'll be traveling abroad before your child is a year old, talk with your child's doctor about getting the measles vaccine earlier.

Preventing new infections

If you've already had measles, your body has built up its immune system to fight the infection, and you can't get measles again. Most people born or living in the United States before 1957 are immune to measles, simply because they've already had it.

For everyone else, there's the measles vaccine, which is important for:

  • Promoting and preserving widespread immunity. Since the introduction of the measles vaccine, measles has virtually been eliminated in the United States, even though not everyone has been vaccinated. This effect is called herd immunity.

    But herd immunity may now be weakening a bit, likely due to a drop in vaccination rates. The rate of measles in the U.S. recently jumped from an average of 60 cases a year to 205 cases annually.

  • Preventing a resurgence of measles. Steady vaccination rates are important because soon after vaccination rates decline, measles begins to come back. In 1998, a now-discredited study was published erroneously linking autism to the measles, mumps and rubella (MMR) vaccine.

    In the United Kingdom, where the study originated, the rate of vaccination dropped to an all-time low of about 80 percent of all children in 2003-2004. In 2008, there were nearly 1,400 lab-confirmed cases of measles in England and Wales.