Measles is an acute, highly communicable rash illness due to a virus transmitted by direct contact with infectious droplets or, less commonly, by airborne spread. The incubation period of measles from exposure to rash onset is generally 14 days (range 7-18) (1). Patients are usually contagious from 4 days before until 4 days after the onset of the rash.
The World Health Organization estimates that more than 30 million individuals are affected each year by measles worldwide (2). As a result of a successful immunization program, measles was declared no longer endemic in the United States in 2000 (3). Since 1997, fewer than 150 cases have been reported annually in the United States. The proportion of importation-associated cases increased from 59% of all reported cases in 1997 to 85% in 2004 (4-6). Approximately half of all imported measles cases occur in U.S. residents returning from visits to foreign countries. Measles remains a common disease in many countries of the world, including some developed countries in Europe and Asia.
Risk for Travelers
Because the risk of exposure to measles among travelers can be high, all travelers leaving the United States should be immune to measles. According to the current Advisory Committee and Immunization Practices recommendations (7), acceptable presumptive evidence of immunity to measles for international travelers includes:
- documented administration of two doses of live measles virus vaccine, or
- laboratory evidence of immunity, or
- birth before 1957, or
- documentation of physician-diagnosed measles.
Onset of illness is characterized by fever, cough, coryza (runny nose), conjunctivitis, and an erythematous maculopapular rash (8). Koplik spots, a rash (enanthem) present on mucous membranes, are considered pathognomonic for measles.
The disease can be severe, and the most frequent complications include diarrhea (8%), middle ear infection (7%-9%), and pneumonia (1-6%). Encephalitis, frequently resulting in permanent brain damage, occurs in approximately 1 per 1000-2000 cases of measles. The risk of severe complications and death is higher among children younger than 5 and adults older than 20 years of age (8).
Although vaccination against measles is not a requirement for entry into any country (including the United States), travelers leaving the United States or living abroad should be sure they are immune to measles.
Measles vaccine contains live, attenuated measles virus. It is available as a measles-mumps-rubella (MMR). Measles vaccine is given subcutaneously in a dose of 0.5 mL. A single dose of measles-containing vaccine administered in the second year of life induces immunity in about 95% of vaccinees (9). More than 99% of individuals who receive two doses separated by at least 28 days, with the first dose administered after the first birthday, develop serologic evidence of measles immunity (1,10).
Use of Measles and MMR vaccine
Children aged 6-11 months leaving the United States should receive a dose of monovalent measles vaccine or MMR if monovalent vaccine is not available. Because immunity conferred by this dose may be lower, revaccination with two doses of measles-containing vaccine is recommended, the first of which should be administered at 12-15 months and the second at least 28 days later (11)
Adverse Reactions to Vaccination
Fever and rash: Fever higher than 39.4° C (103° F) develops in 5%-15% of susceptible vaccinees, usually beginning 7-12 days after MMR vaccination. The measles component is most often associated with this adverse event (13). Transient rashes, usually appearing 7-10 days following vaccination, occur in 5% of persons vaccinated with measles- and rubella-containing vaccines.
Lymphadenopathy or parotitis: Transient lymphadenopathy sometimes occurs following administration of MMR or other rubella-containing vaccine, and parotitis has been rarely reported following vaccination with MMR or other mumps-containing vaccine.
Allergic reactions: Allergic reactions have been reported after MMR vaccine, ranging from mild (urticaria or wheal and flare at the injection site, generalized rash, and pruritis) to severe anaphylactic reactions. Severe allergic reactions are estimated to occur less than once per million doses distributed.
Thrombocytopenia: MMR vaccine can rarely cause clinically apparent low platelet counts within 2 months after vaccination. Clinically apparent thrombocytopenia has been reported at a rate of approximately 1 case per 30,000 vaccinated children. In the United States, the incidence reported by passive surveillance was approximately 1 per 100,000 doses distributed (14).
Arthralgia, arthritis: Approximately 25% of rubella-susceptible postpubertal women who receive MMR or other rubella-containing vaccine may develop arthralgia, and approximately 10% have acute arthritis-like symptoms (15). Joint involvement usually begins 7-21 days after vaccination, and it is usually transient.
Neurologic events: The risk for febrile seizures is approximately 1 case per 3,000 doses of MMR vaccine administered (16). Because the incidence of encephalitis or encephalopathy after measles immunization in the United States is lower than the observed incidence of encephalitis of unknown cause, some or most of the rare reported severe neurologic disorders may be related coincidentally, rather than causally, to measles immunization.
Use of MMRV
The MMRV vaccine is indicated for simultaneous vaccination against measles, mumps, rubella, and varicella among children aged 12 months to 12 years (12). At least 1 month should elapse between a dose of measles-containing vaccine, such as MMR vaccine, and a dose of MMRV vaccine. Should a second dose of varicella vaccine be indicated for children aged 12 month to 12 years (e.g., during a varicella outbreak), at least 3 months should elapse between administration of any two doses of varicella-containing vaccine (12).
Adverse Reactions to Vaccination with MMRV
Rates of most local and systemic adverse events for children immunized with MMRV vaccine were comparable with rates for children immunized with MMR and varicella vaccines administered concomitantly. However, fever higher than 102º F (38.9º C) was observed in 21.5% of MMRV recipients versus 14.9% of MMR and varicella vaccine recipients; and measles-like rash was observed in 3.0% of recipients of MMRV versus 2.1% of those who received MMR and varicella vaccines (12).
Precautions and Contraindications
Persons with severe allergy (i.e., hives, swelling of the mouth or throat, difficulty breathing, hypotension, and shock) to gelatin or neomycin or who have had a severe allergic reaction to a prior dose of MMR or MMRV should not be revaccinated except with extreme caution. MMR or MMRV vaccines may be administered to egg-allergic persons without prior routine skin testing or the use of special protocols.
Replication of vaccine viruses can be potentiated in persons who have immune deficiency disorders. Death related to vaccine-associated measles infection has been reported among severely immunocompromised persons (17). Therefore, severely immunosuppressed individuals should not be vaccinated with MMR or MMRV vaccines.
MMR or MMRV should be avoided for at least 1 month after cessation of high-dose corticosteroid therapy. Some experts, however, recommend waiting only 2 weeks after completion of therapy among individuals receiving high doses of systemic corticosteroids daily or on alternate days even if they were receiving therapy for less than 14 days.
Other immunosuppressive therapy: MMR or MMRV vaccines in general should be withheld for at least 3 months. This interval is based on the assumption that the immunologic responsiveness will have been restored in 3 months and the underlying disease for which the therapy was given is in remission.
The benefits of primary immunization are usually greater than the potential risks. However, avoiding a subsequent dose of MMR or MMRV vaccine may be prudent if an episode of thrombocytopenia occurred within approximately 6 weeks after a previous dose of vaccine.
General Vaccine Recommendations, Pediatric and Catch-Up Schedules, and Recommendations for Special Populations
Refer to Chapters 1, 8 and 9.
PREVENTION OF SPREAD OF MEASLES VIRUS
Persons who are potentially infectious with measles should minimize the risk of spread of the disease by limiting contact with other people who may be susceptible to measles. Contact should be limited until a medical diagnosis has been established excluding measles or 4 days have passed since the onset of the rash. Persons who are potentially infectious with measles should especially avoid public transportation (including commercial airlines) and crowded indoor areas. Patients who suspect they may have measles should call ahead before visiting a clinic or hospital so that arrangements may be made for the health-care provider to attend to the patient without exposing others in the facility to measles.
Care of Exposed Persons
Use of Vaccine
MMR or measles vaccine, if administered within 72 hours of initial measles exposure, may provide some protection. If the exposure does not result in infection, the vaccine should induce protection against subsequent measles infection (1).
Use of Immune Globulin
Immune globulin can be used to prevent or modify measles in a susceptible person within 6 days of exposure. Immune globulin is indicated for household contacts of patients with measles, particularly contacts younger than 1 year, pregnant women, and immunocompromised persons, for whom the risk of complications is higher (1).
The recommended dose is 0.25 mL/kg of body weight given intramuscularly; immunocompromised patients should receive 0.5 mL/kg body weight (Maximum dose 15 mL).
There is no specific antiviral therapy for measles, and the basic treatment consists of providing necessary supportive therapy such as hydration and antipyretics and treating complications such as pneumonia. Vitamin A supplementation improves the outcome of measles among children with vitamin A deficiency and the American Academy of Pediatrics recommends vitamin A in certain circumstances (1).