Symptoms usually develop 10–12 days after exposure to an infected person and last 7–10 days.[7][8] Initial symptoms typically include fever, often greater than 40 °C (104 °F), cough, runny nose, and inflamed eyes.[3][4] Small white spots known as Koplik's spots may form inside the mouth two or three days after the start of symptoms.[4] A red, flat rash which usually starts on the face and then spreads to the rest of the body typically begins three to five days after the start of symptoms.[4] Common complications include diarrhea (in 8% of cases), middle ear infection (7%), and pneumonia (6%).[5] These occur in part due to measles-induced immunosuppression.[6] Less commonly seizures, blindness, or inflammation of the brain may occur.[5][7]
Measles is an airborne disease which spreads easily from one person to the next through the coughs and sneezes of infected people.[7] It may also be spread through direct contact with mouth or nasal secretions.[16] It is extremely contagious: nine out of ten people who are not immune and share living space with an infected person will be infected.[5] Furthermore, measles's reproductive number estimates vary beyond the frequently cited range of 12 to 18.[17] The NIH quote this 2017 paper saying: "[a] review in 2017 identified feasible measles R0 values of 3.7–203.3".[18] People are infectious to others from four days before to four days after the start of the rash.[5] While often regarded as a childhood illness, it can affect people of any age.[19] Most people do not get the disease more than once.[7] Testing for the measles virus in suspected cases is important for public health efforts.[5] Measles is not known to occur in other animals.[16]
Once a person has become infected, no specific treatment is available,[16] although supportive care may improve outcomes.[7] Such care may include oral rehydration solution (slightly sweet and salty fluids), healthy food, and medications to control the fever.[7][8]Antibiotics should be prescribed if secondary bacterial infections such as ear infections or pneumonia occur.[7][16]Vitamin A supplementation is also recommended for children.[16] Among cases reported in the U.S. between 1985 and 1992, death occurred in only 0.2% of cases,[5] but may be up to 10% in people with malnutrition.[7] Most of those who die from the infection are less than five-years old.[16]
The measles vaccine is effective at preventing the disease, is exceptionally safe, and is often delivered in combination with other vaccines.[7][20] Due to the ease with which measles is transmitted from person to person in a community, more than 95% of the community must be vaccinated in order to achieve herd immunity.[21]Vaccination resulted in an 80% decrease in deaths from measles between 2000 and 2017, with about 85% of children worldwide having received their first dose as of 2017.[16]
Measles affects about 20 million people a year,[3] primarily in the developing areas of Africa and Asia.[7] It is one of the leading vaccine-preventable disease causes of death.[22][23] In 1980, 2.6 million people died from measles,[7] and in 1990, 545,000 died due to the disease; by 2014, global vaccination programs had reduced the number of deaths from measles to 73,000.[24][25] Despite these trends, rates of disease and deaths increased from 2017 to 2019 due to a decrease in immunization.[26][27][28]
^ abcdefCaserta, MT, ed. (September 2013). "Measles". Merck Manual Professional. Merck Sharp & Dohme Corp. Archived from the original on 23 March 2014. Retrieved 23 March 2014.