Measles, also known as Rubeola or Morbilli, is caused by a virus and infects the respiratory system. Morbilliviruses are enveloped, single-stranded, negative-sense RNA viruses. Symptoms include fever, cough, runny nose, red eyes and a generalized maculopapular erythematous rash.

It is spread through respiration and is highly contagious. 90% of people without immunity who share a living space with someone infected will get measles. Infection incubates for about 14 days and infectivity lasts 2-4 days prior. In English-speaking countries it is also called Rubeola.

Symptoms include four day fevers, cough, coryza, and red eyes. Fever can get up to 104 °F. Measles usually results in a standard rash that is generalized and usually begins several days after the fever. Usually the rash starts on the head and spreads to cover the rest of the body.

Complications, which are common, usually range from mild to less serious diarrhea, to pneumonia and encephalitis, corneal ulceration leading to corneal scarring. Fatality rate is .3% in developed countries while in under-developed countries the rate gets as high as 28%.

Most patients should be put on respiratory precautions and be isolated from populations until confirmed recovery. Humans are the only known host of measles although it can infect some non-human primate species.

Clinical diagnosis requires a three day fever and at least one of the following: cough, coryza, conjunctivitis. Koplik’s spot is also a diagnostic of measles. Laboratory diagnosis can also be done by isolating measles virus RNA from respiratory specimens. Most children in developed countries are immunized by the age of 18 months. A second dose of vaccine is usually given when the child is between four and five years old. Vaccination rates are also high enough that measles is relatively uncommon.

In developing countries measles can quickly cause an endemic. Vaccine is not effective in HIV-infected infants but the risk of adverse reactions is low. Unvaccinated populations are at risk for disease. In 1998 there were claims that MMR vaccine was connected to autism. This research was later declared untrue.

There is no specific treatment for measles however most uncomplicated cases recover with rest and supportive treatment. Some people develop pneumonia after measles.