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 had about 30 cases of measles in 2004 but more than 600 cases in 2014. Most of these cases originated outside the country and occurred in people who were unvaccinated or who didn't know whether or not they had been vaccinated.

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 a sequence of stages during 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 vaccination records with your doctor, especially before your children start elementary school or college and before international travel.

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% of susceptible people who are exposed to someone with the virus will be infected.

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 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.

The Centers for Disease Control and Prevention recommends that children and adults receive the measles vaccine to prevent measles.

Measles vaccine in children

To prevent measles in children, doctors usually give infants the first dose of the vaccine between 12 and 15 months, with the second dose typically given between ages 4 and 6 years. Keep in mind:

• If you'll be traveling abroad when your child is 6 to 11 months old, talk with your child's doctor about getting the measles vaccine earlier.
• If your child or teenager didn't get the two doses at the recommended times, he or she may need two doses of the vaccine four weeks apart.

Measles vaccine in adults

You may need the measles vaccine if you're an adult who:

• Has an increased risk of measles — such as attending college, traveling internationally or working in a hospital environment — and you don't have proof of immunity. Proof of immunity includes written documentation of your vaccinations or lab confirmation of immunity or previous illness.
• Was born in 1957 or later and you don't have proof of immunity. Proof of immunity includes written documentation of your vaccinations or lab confirmation of immunity or previous illness.

If you're not sure if you need the measles vaccine, talk to your doctor.

Preventing measles during an outbreak or known infection

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 infants older than 6 months and anyone born in 1957 or later who doesn't have written documentation of being vaccinated, or who doesn't have evidence of immunity or having had measles in the past.

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 incidence of measles in the U.S. recently increased significantly.

• 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 incorrectly linking autism to the measles-mumps-rubella (MMR) vaccine.

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

Your doctor can usually diagnose measles based on the disease's characteristic rash as well as a small, bluish-white spot on a bright red background — Koplik's spot — on the inside lining of the cheek. However, many doctors have never seen measles, and the rash can be confused with a number of other illnesses. If necessary, a blood test can confirm whether the rash is truly measles. The measles virus can also be confirmed with a test that generally uses a throat swab or urine sample.

There's no specific treatment for an established measles infection. However, some measures can be taken to protect vulnerable individuals who have been exposed to the virus.

• Post-exposure vaccination. Nonimmunized people, including infants, may be given the measles vaccination within 72 hours of exposure to the measles virus to provide protection against the disease. If measles still develops, the illness usually has milder symptoms and lasts for a shorter time.
• Immune serum globulin. Pregnant women, infants and people with weakened immune systems who are exposed to the virus may receive an injection of proteins (antibodies) called immune serum globulin. When given within six days of exposure to the virus, these antibodies can prevent measles or make symptoms less severe.

Medications

• Fever reducers. You or your child may also take over-the-counter medications such as acetaminophen (Tylenol, others), ibuprofen (Advil, Children's Motrin, others) or naproxen sodium (Aleve) to help relieve the fever that accompanies measles.

  Don't give aspirin to children or teenagers who have measles symptoms. Though aspirin is approved for use in children older than age 3, children and teenagers recovering from chickenpox or flu-like symptoms should never take aspirin. This is because aspirin has been linked to Reye's syndrome, a rare but potentially life-threatening condition, in such children.

• Antibiotics. If a bacterial infection, such as pneumonia or an ear infection, develops while you or your child has measles, your doctor may prescribe an antibiotic.
• Vitamin A. Children with low levels of vitamin A are more likely to have a more severe case of measles. Giving vitamin A may lessen the severity of the measles. It's generally given as a large dose of 200,000 international units (IU) for children older than a year.

If you or your child has measles, keep in touch with your doctor as you monitor the progress of the disease and watch for complications. Also try these comfort measures:

• Take it easy. Get rest and avoid busy activities.
• Sip something. Drink plenty of water, fruit juice and herbal tea to replace fluids lost by fever and sweating.
• Seek respiratory relief. Use a humidifier to relieve a cough and sore throat.
• Rest your eyes. If you or your child finds bright light bothersome, as do many people with measles, keep the lights low or wear sunglasses. Also avoid reading or watching television if light from a reading lamp or from the television is bothersome.

If you suspect that you or your child has measles, you need to see your child's doctor.

What you can do

• Write down any symptoms you or your child is experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
• Write down key personal information, including any recent travel.
• Make a list of all medications, vitamins or supplements that you or your child is taking.
• Write down questions to ask your doctor.

For measles, some basic questions to ask your doctor include:

• What's the most likely cause of my or my child's symptoms?
• Are there other possible causes?
• What treatments are available, and which do you recommend?
• Is there anything I can do to make my child more comfortable?
• Are there any brochures or other printed material that I can take home with me? What websites do you recommend visiting?

What to expect from your doctor

The doctor may ask that you come in before or after office hours to reduce the risk of exposing others to the measles. In addition, if the doctor believes that you or your child has the measles, he or she must report those findings to the local health department.

Your doctor is likely to ask you a number of questions, such as:

• Have you or your child been vaccinated for the measles? If so, do you know when?
• Have you traveled out of the country recently?
• Does anyone else live in your household? If yes, have they been vaccinated for measles?

What you can do in the meantime

While you're waiting to see the doctor:

• Be sure you or your child stays well hydrated. Pediatric electrolyte solutions, such as Pedialyte, or sports drinks, such as Gatorade or Powerade, can help you stay hydrated and maintain your electrolyte balance.

• Bring a fever down safely. If a fever is making you or your child uncomfortable, medications such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Children's Motrin, others) can help bring the fever down.

  Don't give aspirin to children or teenagers who have symptoms of measles. Though aspirin is approved for use in children older than age 3, children and teenagers recovering from chickenpox or flu-like symptoms should never take aspirin. This is because aspirin has been linked to Reye's syndrome, a rare but potentially life-threatening condition, in such children.