Measles is an acute viral infection accompanied by a distinctive red rash. It is considered to be one of the most highly contagious diseases in the world, and therefore it represents a significant public health threat. Fortunately, measles is preventable through vaccination; sadly, many developing nations have incomplete or imperfect vaccination programs, and measles is still a leading cause of death among children in these regions.

Members of the ancient world recognized and wrote about measles; the name for the disease is derived from a Germanic word for “spot,” a reference to the dark, spotty rash which is characteristic of measles. The condition is not related to German measles, better known as rubella. Infection is spread through droplets which are coughed, sneezed, or breathed out. Since the measles virus is airborne, it attacks the respiratory system first, but it doesn't stop there; ultimately, the entire body will be overrun with the measles virus until the disease has run its course.

A measles infection on its own is not inherently dangerous, although it can be uncomfortable and unpleasant. Within two weeks of exposure, the patient will develop a fever and a runny nose, along with a cough and red eyes. Shortly thereafter, a red rash will appear, slowly covering the whole body. Within around five days, the rash subsides, leaving flaky, crackling skin behind. The patient is still infectious for around a week after the rash disappears, but after a case of the measles, the patient will be forever immune.

The risk of measles lies in the complications associated with the illness. While the immune system is busy fighting measles, opportunistic infections may set in throughout the body. Respiratory infections are extremely common, and in some cases the patient may experience extreme symptoms, such as encephalitis, a swelling of the brain which can be fatal. The public health risk in measles lies in these complications, which can overwhelm health services if a large population contracts measles.

Vaccinations for measles became available in 1963, and many children around the world are routinely vaccinated. If a case of measles emerges in a population like a college, the entire population is often revaccinated, to ensure that the disease will not spread. When someone is diagnosed with measles, he or she usually tries to keep inside, so that the condition will not spread. The patient must be kept hydrated and warm, and a doctor may monitor the patient for complications to ensure that the virus runs its course smoothly.