Measles

Measles
Other namesMorbilli, rubeola, red measles, English measles[1][2]
RougeoleDP.jpg
A child showing a day-four measles rash
SpecialtyInfectious disease
SymptomsFever, cough, runny nose, inflamed eyes, rash[3][4]
ComplicationsPneumonia, seizures, encephalitis, subacute sclerosing panencephalitis, immunosuppression[5][6]
Usual onset10–12 days after exposure[7][8]
Duration7–10 days[7][8]
CausesMeasles virus[3]
PreventionMeasles vaccine[7]
TreatmentSupportive care[7]
Frequency20 million per year[3]
Deaths73,400 (2015)[9]

Measles is a highly contagious infectious disease caused by the measles virus.[3][10] 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] Other names include morbilli, rubeola, red measles, and English measles.[1][2] Both rubella, also known as "German measles", and roseola are different diseases caused by unrelated viruses.[11]

Measles is an airborne disease which spreads easily through the coughs and sneezes of infected people.[7] It may also be spread through direct contact with mouth or nasal secretions.[12] 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] People are infectious to others from four days before to four days after the start of the rash.[5] 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]

The measles vaccine is effective at preventing the disease, is exceptionally safe, and is often delivered in combination with other vaccines.[7][13] 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.[12] Once a person has become infected, no specific treatment is available,[12] 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][12] Vitamin A supplementation is also recommended for children.[12]

Measles affects about 20 million people a year,[3] primarily in the developing areas of Africa and Asia.[7] While often regarded as a childhood illness, it can affect people of any age.[14] It is one of the leading vaccine-preventable disease causes of death.[15][16] In 1980, 2.6 million people died of it,[7] and in 1990, 545,000 died; by 2014, global vaccination programs had reduced the number of deaths from measles to 73,000.[9][17] Despite these trends, rates of disease and deaths increased from 2017 to 2019 due to a decrease in immunization.[18][19][20] The risk of death among those infected is about 0.2%,[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.[12] Measles is not known to occur in other animals.[12]

Video summary (script)

Signs and symptoms

Maculopapular rash on the abdomen after 3 days of measles infection

Symptoms typically begin 10–14 days after exposure.[21][22] The classic symptoms include a four-day fever (the 4 D's) and the three C's—cough, coryza (head cold, fever, sneezing), and conjunctivitis (red eyes)—along with a maculopapular rash.[23] Fever is common and typically lasts for about one week; the fever seen with measles is often as high as 40 °C (104 °F).[24]

Koplik's spots seen inside the mouth are diagnostic for measles, but are temporary and therefore rarely seen.[23] Koplik spots are small white spots that are commonly seen on the inside of the cheeks opposite the molars.[22] They appear as "grains of salt on a reddish background."[25] Recognizing these spots before a person reaches their maximum infectiousness can help reduce the spread of the disease.[26]

The characteristic measles rash is classically described as a generalized red maculopapular rash that begins several days after the fever starts. It starts on the back of the ears and, after a few hours, spreads to the head and neck before spreading to cover most of the body, often causing itching. The measles rash appears two to four days after the initial symptoms and lasts for up to eight days. The rash is said to "stain", changing color from red to dark brown, before disappearing.[27] Overall, measles usually resolves after about three weeks.[24]

Complications

Complications of measles are relatively common, ranging from mild ones such as diarrhea to serious ones such as pneumonia (either direct viral pneumonia or secondary bacterial pneumonia), laryngotracheobronchitis (croup) (either direct viral laryngotracheobronchitis or secondary bacterial bronchitis), otitis media,[28] acute brain inflammation[29] (and very rarely subacute sclerosing panencephalitis),[30] and corneal ulceration (leading to corneal scarring).[31]

In addition, measles can suppress the immune system for weeks to months, and this can contribute to bacterial superinfections such as otitis media and bacterial pneumonia.[6][32][33][34][35] Two months after recovered there is a 11–73% of their antibodies against other bacteria and viruses.[36]

The death rate in the 1920s was around 30% for measles pneumonia.[37] People who are at high risk for complications are infants and children aged less than 5 years;[14] adults aged over 20 years;[14] pregnant women;[14] people with compromised immune systems, such as from leukemia, HIV infection or innate immunodeficiency;[14][38] and those who are malnourished[14] or have Vitamin A deficiency.[14][39] Complications are usually more severe in adults who catch the virus.[40] Between 1987 and 2000, the case fatality rate across the United States was three deaths per 1,000 cases attributable to measles, or 0.3%.[41] In underdeveloped nations with high rates of malnutrition and poor healthcare, fatality rates have been as high as 28%.[41] In immunocompromised persons (e.g., people with AIDS) the fatality rate is approximately 30%.[42]

Even in previously healthy children, measles can cause serious illness requiring hospitalization.[38] One out of every 1,000 measles cases progresses to acute encephalitis, which often results in permanent brain damage.[38] One or two out of every 1,000 children who become infected with measles will die from respiratory and neurological complications.[38]