Measles is an infection caused by a virus. Symptoms include fever, cough, runny nose, rash and red eyes ("pink eye" or conjunctivitis). The virus can cause additional complications such as ear infections, pneumonia and diarrhea.
A serious complication is acute encephalitis, or inflammation of the brain, which can result in permanent brain damage in one of every 1,000 cases. In the U.S., death from neurologic or respiratory complications of measles occurs in one to three of every 1,000 cases. In addition, there is a late-onset complication called subacute sclerosing panencephalitis (SSPE). This rare, degenerative and fatal central nervous system disease can occur seven to 11 years after primary measles infection, with the highest rates seen in children infected before 2 years of age.