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.

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 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.