Pictures of measles (rubeola) and disease information have been excerpted from VisualDx clinical decision support system as a public health service. Additional information, including symptoms, diagnostic pearls, differential diagnosis, best tests, and management pearls, is available in VisualDx.

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Measles (rubeola) is a highly contagious, infectious disease caused by a single-stranded RNA virus within the Paramyxoviridae family. The disease is worldwide in distribution. The infection primarily occurs in late winter and spring when individuals are in close contact. Cases are more common in developing countries, as the majority of individuals in industrialized nations have been vaccinated. Classically, the disease is more often seen in children. In an unvaccinated population, children younger than 5 years are at highest risk of infection and death. The disease runs a more severe course in malnourished children.

Measles is transmitted via respiratory droplets and can remain viable and transmissible for up to 2 hours in an airspace after an infected person leaves an area. The incubation period after the measles virus enters the upper respiratory mucosa is about 10 days (range 7-21 days), with the rash typically appearing about 14 days after an exposure. Infected individuals are considered contagious from about 4 days prior to the appearance of the rash through about 4 days after its appearance.

A prodrome characterized by fever (up to 40.5°C [105°F]), coryza (nasal congestion), cough, and conjunctivitis occurs for about 3-4 days followed by the onset of the rash (sometimes immunocompromised individuals do not develop the rash). The coryza, a “barking” cough, and conjunctivitis will increase in severity until the rash reaches its peak. The US Centers for Disease Control and Prevention (CDC) reports that approximately 1 in 10 children with measles will develop otitis media, and up to 1 in 20 will develop pneumonia. Encephalitis is a complication in about 1 in 1000 cases.

Subacute sclerosing panencephalitis (SSPE) is a delayed neurodegenerative disorder occurring approximately 10-11 years after acute infection. This complication is characterized by changes in personality, seizures, and coma and eventuates in death.

Although measles was declared eliminated in the United States in 2000, outbreaks continue to occur. Most cases are associated with importation of measles by unvaccinated international travelers resulting in local outbreaks in communities with clusters of unvaccinated individuals. There was a high number of reported measles cases in the United States in 2014, with 667 cases reported to the CDC, largely from underimmunized communities in Ohio. In 2019, however, an even higher number of confirmed cases was documented: over 1250 cases from 31 states. Since then, the following numbers of cases have been reported annually in the United States: 13 cases in 2020 (8 jurisdictions [jurisdictions include any of the 50 states, New York City, and the District of Columbia]), 49 cases in 2021 (5 jurisdictions), and 121 cases in 2022 (6 jurisdictions). As of February 28, 2023, 3 measles cases have been reported in 2 jurisdictions, including a confirmed case of measles in an individual who attended a large spiritual revival gathering in Kentucky while contagious in mid-February. Refer to the CDC for the latest information on measles cases and outbreaks in the United States.

Related topic: atypical measles

Look For:

Oral lesions called Koplik spots may develop 2-3 days after symptoms begin and prior to the generalized cutaneous eruption. Look for minute, white papules, which may have a central bluish-white portion, usually opposite the second molars on the buccal mucosa. They can also appear red. Bluish-gray or white papules can also be seen on the tonsils. These resolve as the morbilliform rash appears. This enanthem is considered pathognomonic for measles.

The exanthem consists of erythematous macules and papules beginning at the forehead and behind the ears, eventually spreading in a cephalocaudal fashion down the neck, upper extremities, trunk, and lower extremities. Confluent lesions can occur on the face. The rash typically peaks for 3-4 days, then begins to fade at day 5 in the same manner in which it appeared. Desquamation typically occurs after approximately 1 week. Thrombocytopenia, with resultant purpuric lesions, may complicate measles.

Variant: Atypical measles (in those receiving formalin-inactivated measles vaccine between 1963 and 1968 or in whom immunization has failed) will spread from the extremities inward. Petechiae, purpura, vesicles, or acral edema can occur. Cough and conjunctivitis are not as marked as in classic measles.

Impact of skin color on clinical presentation: In darker skin colors, erythema may be subtler or may appear more violaceous or hyperpigmented. Applying brief gentle pressure with a fingertip or microscope slide to blanch involved skin may accentuate subtle erythema as the pressure is withdrawn. Use of a bright light may further illuminate any subtle color changes present. In lighter skin colors, the active border may be any shade of pink or red. In skin of intermediate color, erythema may be deep red, maroon, or violaceous. Postinflammatory hyperpigmentation is more prominent and lasts longer in darker skin colors.

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