Measles is a viral infection characterized by a red, bumpy rash.

What is going on in the body?

Measles is acquired by coming into contact with infected respiratory secretions and droplets. Infected people can spread it when they cough, sneeze or wipe their noses.

The measles vaccine has greatly reduced the number of measles cases in the United States. Usually, measles is imported into this country by travelers.

What are the causes and risks of the infection?

Measles is caused by the measles virus, which belongs to the Paramyxovirus family of viruses.

About 0.1% of patients can contract encephalitis, an infection of the brain after becoming infected with measles. Encephalitis can result in brain damage and, sometimes, death.

Rarely, many years after the first measles infection, a person may develop subacute sclerosing panencephalitis. This is a condition characterized by behavioral changes, mental decline and seizures.