Also called rubeola or morbilli, measles is a viral infection in the respiratory system caused by a paramyxovirus of the genus Morbillivirus. The "rubeola" term for the disease in English-speaking countries is at times confused with "rubella" or German measles. The disease is highly contagious, being able to contract new persons without immunity through aerosol transmission or contact with fluids from an infected person's nose and mouth.
Signs and symptoms include four-day fevers that may be as high as 40 °C (104 °F), cough, runny nose, and red eyes or conjunctivitis. Generalized, maculopapular, erythematous rash moreover appears several days after fever is detected. The typically itchy rash starts to occur on the head before covering most of the body. Complications associated with the disease are diarrhea, pneumonia, acute encephalitis, and corneal ulceration that can lead to corneal scarring. Adults infected by the disease tend to suffer more serious complications compared to young patients.