Summarize:

The most identifiable sign of the measles is the rash it causes, which shows up a few days after the coughing, sore throat and running nose appear. The rash consists of many small red spots and bumps in tight clusters, some of which are slightly raised, but mostly it looks like large flat blotches from a distance. The head / face are the first to break out, with the rash showing up behind the ears and close to the hairline. Over the next couple of days, the rash spreads to the neck, arms and torso, then down the legs to the feet. The rash isn't itchy for most people, but can irritate those with sensitive skin.  People with measles typically feel the most ill on the first or second day after the rash develops, and then it takes about a week to fade completely away.  Shortly after the rash appears, fever usually rises sharply and can reach or exceed 104 F. Medical attention may be necessary at this stage. Many people with measles also develop small grayish-white spots in their mouth (inner cheeks), which are called Koplik's spots. Measles typically begins with nonspecific signs and symptoms, such as malaise (tiredness) and a mild-to-moderate fever. Thus, if your child seems listless with a poor appetite and has a mild temperature, then chances are good they have a viral infection. However, most viral infections begin the same way, so a mild fever is not a strong identifier for measles by itself.  Normal body temperature is 98.6 F, so a fever for a child is any temperature over 100.4 F. A temperature greater than 104 F in children warrants medical attention. A digital ear thermometer, also called a tympanic thermometer, is a quick and easy way to measure a child's temperature. Measles has an incubation period of 10 to 14 days post infection, which is a period of no signs or symptoms. Just after you notice a mild-to-moderate fever in your child, then other symptoms quickly develop with measles. A persistent cough, sore throat, runny nose and inflamed eyes (conjunctivitis) are typical of the early stages of the measles. This relatively mild collection of symptoms may last two or three days after the onset of the fever. These signs still don't clearly identify your child's illness as measles — other viral infections, such as the common cold and flu, cause very similar symptoms.  The cause of measles is the paramyxovirus, which is highly contagious. It spreads through droplets in the air or on surfaces, then replicates in the nose and throat of an infected person. You can contract paramyxovirus by putting your fingers in your mouth / nose or by rubbing your eyes after touching any infected surface. Getting coughed or sneezed on by an infected person can spread the measles also. A person infected with measles can spread the virus to other people for a period of about eight days — starting when symptoms begin and lasting until the fourth day of the rash (see below). While people who receive the complete vaccine series for measles have almost no risk of getting the disease, certain groups of people are at higher risk for measles. The most at risk are people who: don't get the entire measles vaccine series, have a vitamin A deficiency and/or travel to places where measles are common (Africa and parts of Asia, for examples). Other groups more susceptible to measles are those with weakened immune systems and children younger than 12 months old (because they are too young to be eligible to receive the vaccine).  The measles vaccine is usually combined with others that protect from the mumps and rubella. All combined, the vaccine is known as the MMR vaccine. People who get immunoglobulin treatment and the MMR vaccine at the same time are also at higher risk of developing the measles. Vitamin A has antiviral properties and is very important for the health of mucus membranes, which line the nose, mouth and eyes. If your diet is deficient in vitamin, you're more likely to get the measles and experience more severe symptoms.
Watch for a distinctive red rash. Check for a fever. Look out for coughing, sore throat and a runny nose. Recognize who's at high risk.