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Measles is
a highly contagious, viral infection that is most common in children.
It is characterized by fever, cough, coryza, conjunctivitis, enanthem
(Koplik's spots) on the buccal or labial mucosa, and a maculopapular
rash that spreads cephalocaudally. Diagnosis is usually clinical.
Treatment is supportive. Vaccination is highly effective.
Worldwide, measles infects about 30 to 40 million annually, causing about 800,000 deaths, primarily in children. It is less common in the US because of routine childhood vaccination; about 100 to 300 cases occur annually.
Etiology
and Epidemiology
Measles is caused by a paramyxovirus. It is extremely communicable and is spread mainly by secretions from the nose, throat, and mouth during the prodromal or early eruptive stage or by airborne droplets. Communicability continues from several days before until several days after the rash appears. Measles is not communicable once desquamation begins.
An infant whose mother has had measles receives antibodies transplacentally that are protective for most of the 1st year of life. Lifelong immunity is conferred by infection. In the US, many measles cases are imported by travelers or immigrants.
Symptoms and Signs
Measles begins, after a 7- to 14-day incubation period, with a prodrome of fever, coryza, hacking cough, and tarsal conjunctivitis. The pathognomonic Koplik's spots appear 2 to 4 days later, usually on the buccal mucosa opposite the 1st and 2nd upper molars. They resemble grains of white sand surrounded by red areolae. They may be extensive, producing diffuse mottled erythema of the buccal mucosa. Sore throat develops.
The rash appears 3 to 5 days after symptom onset, usually 1 to 2 days after Koplik's 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 h, 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 severe rashes.
During peak disease severity, the 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 and the epidemic. In 3 to 5 days, the fever falls, the patient feels more comfortable, and the rash fades rapidly, leaving a coppery brown discoloration followed by desquamation.
Immunocompromised patients may not have a rash and can develop severe, progressive giant cell pneumonia.
Atypical measles syndrome usually occurs in people previously immunized with the original killed virus measles vaccines, which have been unavailable since 1968. The older vaccines can alter disease expression. Atypical measles syndrome may begin abruptly, with high fever, prostration, headache, abdominal pain, and cough. The rash may appear 1 to 2 days later, often beginning on the extremities, and may be maculopapular, vesicular, urticarial, or purpuric. Edema of the hands and feet may occur. Pneumonia and hilar adenopathy are common, and may be prolonged; chest x-ray abnormalities may persist for weeks to months. Symptomatic hypoxemia may occur.
Bacterial superinfections include pneumonia, otitis media, and others. Measles transiently suppresses delayed hypersensitivity, which can worsen active TB and temporarily prevent reaction to tuberculin and histoplasmin antigens on skin tests. Bacterial superinfection is suggested by pertinent focal signs or a relapse of fever, leukocytosis, or prostration.
Acute thrombocytopenic purpura may occur after infection resolves and produce a mild, self-limited bleeding tendency, although occasionally bleeding is severe.
Encephalitis occurs in 1/1000 to 2000 cases, usually 2 days to 1 wk after onset of the rash, often beginning with high fever, headache, seizures, and coma. CSF usually has a lymphocyte count of 50 to 500/μL and a mildly elevated protein level but may be normal initially. Encephalitis may resolve in about 1 wk or may persist longer, causing morbidity or death.
Subacute sclerosing panencephalitis (SSPE) is a late complication (see Other Viruses: Subacute Sclerosing Panencephalitis (SSPE)).
Diagnosis
Typical measles may be suspected in an exposed patient who has coryza, conjunctivitis, photophobia, and cough but usually is suspected only after the rash appears. Diagnosis is usually clinical, by identifying Koplik's spots or the rash. CBC is unnecessary but, if obtained, may show leukopenia with a relative lymphocytosis. Laboratory identification is necessary only for public health and outbreak control purposes and is rarely performed to make the diagnosis. It is most easily done by demonstrating the presence of measles IgM in an acute serum specimen or, alternatively, by rapid immunofluorescent staining of pharyngeal or urinary epithelial cells, by reverse transcription–PCR of throat swabs or urine samples, or by viral growth in tissue culture. A rise in IgG antibody levels between acute and convalescent sera is highly accurate but delays diagnosis.
Differential diagnosis includes rubella, scarlet fever, drug rashes (eg, from phenobarbital or sulfonamides), serum sickness, roseola infantum, infectious mononucleosis, erythema infectiosum (see Infections in Infants and Children: Erythema Infectiosum), and echovirus and coxsackievirus infections (see also Table 1: Viruses: Selected Viruses That Infect Humans*  ). Atypical measles, because of its greater variability, can simulate even more conditions than typical measles. Features that distinguish rubella from typical measles can include the absence of a recognizable prodrome, absence or milder severity of fever and other constitutional symptoms, enlarged (and usually tender) postauricular and suboccipital lymph nodes, and short duration. Drug rashes often resemble the measles rash but can usually be distinguished by the absence of a prodrome, cephalocaudal progression, or cough and the history. Roseola infantum can produce a skin rash similar to that of measles, but it seldom occurs in children > 3 yr. It can usually be differentiated by the high initial temperature, absence of Koplik's spots and malaise, and the simultaneity of defervescence and appearance of the rash.
Prognosis
and Treatment
Mortality is about 2/1000 in the US but much higher in the developing world. Undernutrition and vitamin A deficiency may predispose to mortality. Vitamin A supplementation is recommended in populations at risk.
Cases of suspected measles should be reported immediately to local or state health departments without waiting for laboratory confirmation. Treatment is supportive, including for encephalitis. Vitamin A reduces morbidity and mortality in malnourished children but is not needed in others. For children > 1 yr with ophthalmologic evidence of vitamin A deficiency, 200,000 international units (IU) po is given daily for 2 days and repeated in 4 wk. Children living in regions where vitamin A deficiency is common receive a single dose of 200,000 IU. Children 6 mo to 1 yr receive a single dose of 100,000 IU.
Prevention
A live attenuated virus vaccine is routinely given to children in most developed countries (see also Immunization: Measles, Mumps, and Rubella; see also Approach to the Care of Normal Infants and Children:Health Supervision of the Well Child for Fig. Fig. 3: Approach to the Care of Normal Infants and Children: Recommended childhood and adolescence immunization schedule.). The 1st dose is recommended at age 12 to 15 mo but can be given as young as 6 mo during a measles outbreak. Two doses are recommended. Infants immunized at < 1 yr of age still require 2 further doses given after the first birthday. Vaccine provides long-lasting immunity and has decreased measles incidence in the US by 99%. The vaccine produces mild, or inapparent, noncommunicable infection. Fever > 38° C occurs 5 to 12 days after inoculation in < 5% of vaccinees and can be followed by a rash. CNS reactions are exceedingly rare; the vaccine does not cause autism.
Contraindications to the vaccine include generalized malignancies (eg, leukemia, lymphoma), immunodeficiency, and therapy with immunosuppressants, such as corticosteroids, irradiation, alkylating agents, or antimetabolites. HIV infection is a contraindication only if there is severe immunosuppression(CDC immunologic category 3 with CD4+ < 15%); if not, the risks of wild measles outweigh the risk of acquiring measles from the live vaccine. Reasons to defer vaccination include pregnancy, serious febrile illness, active untreated TB, or administration of antibody (as whole blood, plasma, or any immune globulin). The duration of deferral depends on the type and dose of immune globulin preparation given but may be as long as 11 mo.
Prevention in susceptible contacts is possible by giving the vaccine within 3 days of exposure. If vaccine should be deferred, immune serum globulin 0.25 mL/kg IM (maximum dose 15 mL) is given immediately, with vaccination given 5 to 6 mo later if medically appropriate (eg, patient no longer pregnant). An exposed immunodeficient patient with a contraindication to vaccination is given immune serum globulin 0.5 mL/kg IM (maximum, 15 mL). Immune serum globulin should not be given simultaneously with vaccine.
Last full review/revision November 2005
Content last modified November 2005
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