Contributor: Gordon K. Klintworth
Rubeola (measles) is a highly communicable acute febrile viral infection characterized by a upper respiratory tract symptoms, fever, a maculopapular rash, conjunctivitis, and coryza. The pathogen is an RNA virus belonging to the Paramyxoviridae. Before the development of a measles vaccine in the early 1960s rubeola was endemic in most parts of the world and major epidemics were common. Despite the widespread use of a live-attenuated measles vaccine measles remains a common infection worldwide (~40 million cases/year). The infection accounts for the death of >1 million infants annually. In the USA and developed countries measles infection has become uncommon as a result of vaccination. After an incubation period (1-2 weeks) the prodromal phase of measles begins with fever, rhinorrhea, cough and conjunctivitis. A watery discharge is often associated with the conjunctivitis. Subconjunctival hemorrhage [hemorrhage - conjunctiva] sometimes develops and a bilateral epithelial keratitis [keratitis - epithelial] is almost always present. Koplik spots develop in the mouth before an erythematous maculopapular rash starts on the face. The rash subsequently spreads to the trunk and limbs. In most cases recovery is rapid and complete, but complications can arise and may be serious. They include bacterial and viral superinfections and an abnormal host-immune reaction. Complications include secondary bacterial pneumonia, otitis media, sinusitis, febrile convulsions, encephalitis, abnormal liver function, chronic diarrhea. In rare cases uveitis, chorioretinitis, optic neuritis and retinal vein occlusion has been associated with measles. In parts of Africa post-measles blindness is common and serious. It is usually accompanied by corneal scarring of the cornea. The cause is poorly understood, but malnutrition, vitamin A deficiency, coexistent herpes simplex infection and the toxic effect of home remedies seem to be risk factors. CD46 is the receptor for the measles virus. Measles is associated with two types of multinucleated giant cells. During the incubation period lymphoid tissue throughout the body develops the Warthin-Finkeldey cell. Within the epithelium of all major organs an epithelial giant cell also forms. One manifestation of infection with the measles virus is subacute sclerosing panencephalitis, which occurs in individuals with a normal immune system, but with mutations in membrane proteins of the measles virus. Measles is preventable with vacination, but it still a major public health problem in developing countries. Ophthalmic manifestations of measles include conjunctivitis and keratitis.