Amy A. Parker, Amra Uzicanin

Infectious Agent

• Measles virus is a member of the genus Morbillivirus of the family Paramyxoviridae.
• Humans are the only known natural host for the measles virus.
• Measles, also known as rubeola, is one of the most highly communicable infectious diseases.

Mode of Transmission

• Measles spreads by airborne droplets.
• Direct contact with nasal or throat secretions of infected persons.
• Less commonly it is spread by articles freshly soiled with nose and throat secretions.
• Infected persons are usually contagious from 4 days before onset of signs or symptoms, and until 4 days after the onset of signs or symptoms.

Occurrence

• An estimated 20 million measles cases still occur globally every year, and travelers could be exposed in almost any country they visit. However, the risks are greater in countries where measles remains endemic or where large outbreaks are occurring.
• In the Americas, indigenous measles circulation was interrupted in 2002, but risk of measles due to virus importations from other parts of the world still remains.
• The number of reported measles cases in the United States has declined from 894,134 in 1941 to fewer than 150 cases each year since 1997. However, from January 1 through April 25, 2008, a total of 64 confirmed measles cases were reported to CDC, which is the largest number of cases reported in the United States for the corresponding period for any year since 2001. Ten of these cases were acquired abroad by unvaccinated travelers (five in visitors to the United States and five in U.S. residents) and the remaining cases were considered to be associated with these importations of measles.

Risk for Travelers

• All persons who do not have evidence of measles immunity are at risk for contracting measles during international travel.
• Acceptable presumptive evidence of immunity to measles for international travelers includes—
  • For infants 6–11 months of age, documented administration of one dose of live measles-containing vaccine¹ and, for persons ≥12 months of age, two doses of MMR² vaccine at least 28 days apart, on or after the first birthday
  • Laboratory evidence of immunity
  • Birth before 1957
  • Documented physician-diagnosed measles

Clinical Presentation

• Incubation period is ~10 days (range 7–18 days) from exposure to onset of fever, usually 14 days before appearance of rash.
• Symptoms include prodromal fever, conjunctivitis, coryza, cough, and small spots with white or bluish white centers on an erythematous base on the buccal mucosa (Koplik spots).
• Characteristic red, blotchy (maculopapular) rash appears on third to seventh day that begins on the face, becomes generalized, and lasts 4–7 days.
• 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 1,000–2,000 cases of measles. Subacute sclerosing panencephalitis (SSPE), a rare but serious degenerative central nervous system disease, is thought to occur in 1 per 100,000 cases, although a risk of 22 cases of SSPE per 100,000 measles cases was found during the 1989–1991 measles resurgence in the United States. SSPE, which is caused by a persistent infection with a defective measles virus, is manifested by mental and motor deterioration that starts an average of 7 years after measles virus infection (most frequently in children <2 years of age), progressing to coma and death.
• The risk of serious complications and death is highest for children ≤5 years of age and adults ≥20 years of age. It is also higher in populations with poor nutritional status.

Diagnosis

• A clinical case of measles illness is characterized by all of the following:
  • Generalized maculopapular rash lasting ≥3 days
  • Temperature ≥101° F (≥38.3° C)
  • Cough, coryza, or conjunctivitis
• Laboratory criteria for diagnosis is a positive serologic test for measles immunoglobulin M (IgM) antibody, seroconversion or significant rise in measles IgG antibody level by any standard serologic assay, or isolation of measles virus or identification by PCR of measles virus RNA from a clinical specimen.
• A confirmed case is either laboratory confirmed or meets the clinical case definition and is epidemiologically linked to a confirmed case. A laboratory-confirmed case does not need to meet the clinical case definition.

Treatment

• There is no specific antiviral therapy or treatment for measles.
• Supportive therapy includes hydration, antipyretics, and treating complications such as pneumonia.
• The WHO currently recommends vitamin A for all children with acute measles, regardless of their country of residence, to reduce morbidity and mortality. Vitamin A is administered once a day for 2 days, at the following doses:
  • 50,000 IU for infants <6 months of age
  • 100,000 IU for infants 6–11months of age
  • 200,000 IU for children ages 12 months or older
• A third age-specific dose of vitamin A is to be given 2–4 weeks later to case-patients with clinical signs and symptoms of vitamin A deficiency. Parenteral and oral formulations of vitamin A are available in the United States.

Preventive Measures for Travelers

Vaccine

• Measles vaccine contains live, attenuated measles virus. It is available as a monovalent formulation and in combination formulations, such as measles–rubella (MR), measles–mumps–rubella (MMR), and measles–mumps–rubella–varicella (MMRV).
• Ensure that all travelers who do not have evidence of measles immunity (see Risk for Travelers earlier in this section) are up to date on measles vaccination prior to departure.
  • Infants 6–11 months of age should have at least one dose of measles-containing vaccine.¹
  • Preschool children ≥12 months of age should have two doses of MMR² vaccine separated by at least 28 days.
  • School-age children should have two doses of MMR.²
  • Adults born in or after 1957 should have two doses of measles-containing vaccine.
  • If administered at ≥12 months of age, one dose of measles-containing vaccine or MMR is 95% effective in preventing measles disease and two doses are 99% effective. One dose of measles-containing vaccine or MMR is approximately 85% effective if administered at 9 months of age.
• For persons ≥12 months of age, combined MMR vaccine is recommended whenever one or more of the individual components is indicated to provide optimal protection against mumps and rubella. For infants <12 months of age, measles vaccine alone is recommended if it is available; otherwise MMR should be used.
• MMR 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 virus infection.
• Immune globulin (IG) can be used to prevent or mitigate measles in a susceptible person when administered within 6 days of exposure. However, any immunity conferred is temporary unless modified or typical measles occurs, and the person should receive measles-containing vaccine 5–6 months after IG administration.

Adverse Reactions, Precautions, and Contraindications to Measles Vaccine

Allergy

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.

Immunosuppression

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. 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.

Thrombocytopenia

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.

Footnotes:

¹Measles vaccine alone is recommended for infants vaccinated before 12 months of age if it is available, otherwise MMR should be administered. Infants vaccinated before 12 months of age must be revaccinated on or after the first birthday with two doses of measles-containing vaccine separated by at least 28 days. MMRV is not licensed for children <12 months of age.

²MMRV vaccine is licensed for children 12 months to 12 years of age and may be used in place of MMR vaccine if vaccination for measles, mumps, rubella and varicella are needed.

References

1. American Academy of Pediatrics. Measles. In: Pickering LK, Baker CJ, Long SS, McMillan JA, editors. Red book: 2006 report of the Committee on Infectious Diseases. 27th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2006. p. 441–52.
2. WHO. Measles fact sheet. 2007 Nov [cited 2008 Nov 25] Available from: http://www.who.int/mediacentre/factsheets/fs286/en/.
3. CDC. Progress toward measles elimination—Region of the Americas, 2002–2003. MMWR. Morbid Mortal Wkly Rep. 2004;53(14);304–6.
4. CDC. Measles—United States, January 1–April 25, 2008. MMWR Morb Mortal Wkly Rep. 2008;57:1–4.
5. CDC. Measles, mumps, and rubella-vaccine use and strategies for elimination of measles, rubella, and congenital rubella syndrome and control of mumps: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Morbid Mortal Wkly Rep. 1998;47(RR-8):1–57.
6. CDC. Update: recommendations from the Advisory Committee on Immunization Practices (ACIP) regarding administration of combination MMRV vaccine. MMWR Morbid Mortal Wkly Rep. 2008;57(10);258–60.
7. Strebel PM, Papania MJ, dayan GH, et al. Measles vaccine. In: Plotkin SA, Orenstein WA, Offit PA, editors. Vaccines. 5th ed. Philadelphia: Saunders Elsevier; 2008. p. 353–98.
8. Bellini WJ, Rota JS, Lowe LE, et al. Subacute sclerosing panencephalitis: more cases of this fatal disease are prevented by measles immunization than was previously recognized. J Infect Dis. 2005;192(10):1686–93.
9. Perry RT, Halsey NA. The clinical significance of measles: a review. J Infect Dis. 2004;189 Suppl 1;S4–16.
10. CDC. Measles (rubeola) 2007 case definition. 2008 Jan 9 [cited 2008 Nov 25]. Available from:  http://www.cdc.gov/ncphi/disss/nndss/casedef/measles_current.htm.
11. American Academy of Pediatrics. Measles. In: Pickering LK, Baker CJ, Long SL, Kimberlin DW, editors. Red book: 2006 report of the Committee on Infectious Diseases. 27th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2006.
12. CDC. Recommended childhood and adolescent immunization schedule—United States, 2006. MMWR Morb Mortal Wkly Rep. 2006;54(52):Q1–4.