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AT-A-GLANCE
Prodrome of fever, cough, coryza, and conjunctivitis
Koplik spots on the buccal mucosa are pathognomonic
Morbilliform eruption lasts 3 to 5 days
Severe complications include pneumonia and post-measles encephalomyelitis
Vitamin A treatment may reduce morbidity and mortality
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Measles, or rubeola, is a highly contagious, viral disease that remains an important cause of morbidity and mortality worldwide. The incidence and mortality rates are highest in developing countries, particularly in Africa and Asia where large populations are unvaccinated.
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A measles vaccine was first licensed in the United States in 1968. Prior to the introduction of the vaccine, approximately 90% of Americans were infected with measles prior to 15 years old.1 By 2000, endemic transmission of measles within the United States ceased and measles was declared eliminated.2 However, measles outbreaks continue to occur in the United States partly because of travel to countries with higher rates of measles and the spread of the virus in U.S. communities with pockets of unvaccinated people.3 For instance, a multistate outbreak in late 2014 as a consequence of transmission at Disneyland in Anaheim, California, was responsible for 111 of the total 189 cases of measles in the United States in 2015.4
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Worldwide, measles rates have also precipitously declined as the result of the implementation of measles vaccine programs. As of 2014, 85% of children across the globe had received at least 1 dose of the measles vaccine.5 Despite this improvement, measles is still a leading cause of childhood mortality with 114,900 deaths in 2014.5 The epidemiology of measles in the developing world is highly dependent on funding resources, public health infrastructure and political stability.
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ETIOLOGY AND PATHOGENESIS
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Measles virus is a highly contagious, single-stranded, enveloped RNA virus that is a member of the Paramyxoviridae family. Humans are the only natural hosts. Transmission occurs via person-to-person contact or airborne respiratory secretions. Infectious droplets have been reported to remain airborne for up to 2 hours, allowing for easy transmission in public spaces.6
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The measles virus enters the host via the respiratory mucosa or conjunctiva where it can replicate, spread locally to lymphatic nodes and later disseminate into the bloodstream. The humoral immune system controls viral replication and confers antibody protection, whereas the cell-mediated response eliminates infected cells. A transient immunosuppression occurs during measles virus infection, causing depressed delayed-type hypersensitivity and T-cell counts, as well as an increased risk of bacterial infections.7
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Measles infection is characterized by an incubation period, prodrome and exanthem. The incubation period from acquiring the virus to developing fever ranges between 7 and 21 days.
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The prodrome consists of fever (as high as 40.5°C [104.9°F]), malaise, conjunctivitis (palpebral, extending to lid margin), coryza, and cough (brassy or barking) and ...