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Measles is caused by a paramyxovirus and is a human disease with no known animal reservoir or asymptomatic carrier state. It is extremely communicable; the secondary attack rate is > 90% among susceptible people who are exposed.

Measles is spread mainly by secretions from the nose, throat, and mouth during the prodromal or early eruptive stage. Communicability begins several days before and continues until several days after the rash appears. Measles is not communicable once the rash begins to desquamate.

Transmission is typically by large respiratory droplets that are discharged by cough and briefly remain airborne for a short distance. Transmission may also occur by small aerosolized droplets that can remain airborne (and thus can be inhaled) for up to 2 hours in closed areas (eg, in an office examination room). Transmission by fomites seems less likely than airborne transmission because the measles virus is thought to survive only for a short time on dry surfaces.

An infant whose mother has immunity to measles (eg, because of previous illness or vaccination) receives antibodies transplacentally; these antibodies are protective for most of the first 6 to 12 months of life. Lifelong immunity is conferred by infection.

In the United States, almost all measles cases are imported by travelers or immigrants, with subsequent community transmission occurring primarily among unvaccinated people.

After a 7- to 14-day incubation period, measles begins with a prodrome of fever, coryza, hacking cough, and tarsal conjunctivitis. Koplik spots (which resemble grains of white sand surrounded by red areolae) are pathognomonic. These spots appear during the prodrome before the onset of rash, usually on the oral mucosa opposite the 1st and 2nd upper molars. They may be extensive, producing diffuse mottled erythema of the oral mucosa. Sore throat develops.

Measles (Koplik Spots)

Сховати деталі

Koplik spots are classically described as being bright red spots with white or bluish-white centers that may resemble grains of sand. They may occur anywhere in the mouth, often precede the generalized exanthem, and are pathognomonic for measles (rubeola).

Images courtesy of the Public Health Image Library of the Centers for Disease Control and Prevention.

The rash appears 3 to 5 days after symptom onset, usually 1 to 2 days after Koplik spots appear. It begins on the face in front of and below the ears and on the side of the neck as irregular macules, soon mixed with papules. Within 24 to 48 hours, lesions spread to the trunk and extremities (including the palms and soles) as they begin to fade on the face. Petechiae or ecchymoses may occur with in severe cases.

Measles (Macular Rash)

Сховати деталі

Measles (rubeola) manifests as a diffuse macular rash that becomes confluent.

Image courtesy of the Public Health Image Library of the Centers for Disease Control and Prevention.

During peak disease severity, a patient’s temperature may exceed 40° C, with periorbital edema, conjunctivitis, photophobia, a hacking cough, extensive rash, prostration, and mild itching. Constitutional symptoms and signs parallel the severity of the eruption.

In 3 to 5 days, the fever decreases, the patient feels more comfortable, and the rash fades rapidly, leaving a coppery brown discoloration followed by desquamation.

Patients who are immunocompromised may not have a rash and can develop severe, progressive giant cell pneumonia.

• History and physical examination

• Serologic testing

• Viral detection via culture or reverse transcription–polymerase chain reaction (RT-PCR)

Measles may be suspected in an exposed patient who has coryza, conjunctivitis, photophobia, and cough but is usually suspected only after the rash appears. Diagnosis is usually clinical, by identifying Koplik spots or the rash in an appropriate clinical context. A complete blood count is unnecessary but, if obtained, may show leukopenia with a relative lymphocytosis.

Laboratory confirmation is necessary for public health outbreak control purposes. It is most easily done by demonstration of the presence of measles IgM antibody in an acute serum specimen or by viral culture or RT-PCR of throat swabs, blood, nasopharyngeal swabs, or urine samples. A rise in IgG antibody levels between acute and convalescent sera is highly accurate, but obtaining this information delays diagnosis. All cases of suspected measles should be reported to the local health department even before laboratory confirmation.

Differential diagnosis includes rubella, scarlet fever, drug rash, serum sickness (see table Some Causes of Urticaria), roseola infantum, infectious mononucleosis, erythema infectiosum, and echovirus and coxsackievirus infections (see table Some Respiratory Viruses). Manifestations can also resemble Kawasaki disease. The presenting symptoms and signs may cause diagnostic confusion in areas where measles is very rare.

Some of these conditions can be distinguished from typical measles as follows:

• Rubella: A recognizable prodrome is absent, fever and other constitutional symptoms are absent or less severe, postauricular and suboccipital lymph nodes are enlarged (and usually tender), and duration is short.

• Drug rash: A rash caused by drug hypersensitivity often resembles the measles rash, but a prodrome is absent, there is no cephalocaudal progression or cough, and there is usually a history of recent drug exposure.

• Roseola infantum: The rash resembles that of measles, but it seldom occurs in children > 3 years of age. Initial temperature is usually high, Koplik spots and malaise are absent, and defervescence and rash occur simultaneously.

• Supportive care

• For children, vitamin A

Treatment of measles is supportive, including for encephalitis.

Patients are most contagious for 4 days after the development of the rash. Patients who are otherwise healthy and can be managed as outpatients should be isolated from others during their illness.

Hospitalized patients with measles should be managed with standard and airborne precautions. Single-patient airborne infection isolation rooms and N-95 respirators or similar personal protective equipment are recommended.

Vitamin A supplementation has been shown to reduce morbidity and mortality due to measles in children in medically underserved areas. Because low serum levels of vitamin A are associated with severe disease due to measles, vitamin A treatment is recommended for all children with measles. The dose is given orally once a day for 2 days and depends on the child’s age:

• ≥ 12 months: 200,000 international units (IU)

• 6 to 11 months: 100,000 IU

• < 6 months: 50,000 IU

In children with clinical signs of vitamin A deficiency, an additional single, age-specific dose of vitamin A is repeated 2 to 4 weeks later.

Mortality is approximately 1 to 2/1000 children in the United States, but is much higher in medically underserved countries (1). Undernutrition and vitamin A deficiency may predispose to mortality.

The CDC estimates that worldwide approximately 134,000 people die each year of measles, typically from complications of pneumonia or encephalitis.

A live-attenuated virus vaccine containing measles, mumps, and rubella (MMR) is routinely given to children in most nations that have a robust health care system (see also Childhood Vaccination Schedule).

Two doses are recommended:

• The first dose at age 12 to 15 months but can be given as young as age 6 months during a measles outbreak or before international travel

• The second dose at age 4 to 6 years

Infants immunized at < 1 year of age still require 2 additional doses given after their first birthday.

MMR vaccination generally provides lasting immunity and has decreased measles incidence in the United States by 99% (1). A large meta-analysis of cohort studies found the effectiveness of the MMR vaccine in preventing measles in children from age 9 months to 15 years was 95% after one dose and 96% after two doses (2).

The vaccine causes mild or inapparent, noncommunicable infection. Fever > 38° C occurs 5 to 12 days after inoculation in 5 to 15% of vaccinees and can be followed by a rash. Central nervous system reactions are exceedingly rare. The MMR vaccine does not cause autism.

MMR is a live vaccine and is contraindicated during pregnancy.

See MMR Vaccine for more information, including indications, contraindications and precautions, dosing and administration, and adverse effects.

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

1. CDC: Measles Cases and Outbreaks statistics