Measles (Rubeola)

Measles is a highly contagious viral illness caused by an RNA virus. It is found worldwide and has a very distinct clinical picture, characterized by fever, malaise, cough, conjunctivitis, coryza, and rash.

A child showing a day-four measles rash
https://en.wikipedia.org/wiki/Measles

Epidemiology

• Most cases are in the unimmunized or infants too young to have received the vaccine
• Measles is still common in many parts of the world, including parts of Europe, Asia, and Africa 
• In the United States, measles was declared eliminated in 2000
• ​Since then, the annual number of US cases has ranged from a low of 37 in 2004 to a high of 667 in 2014
  • In recent years, there have been multiple large outbreaks in the US, all occurring in groups of people who are unvaccinated
  • There have been 465 cases of measles in the US from Jan 1 - April 4, 2019

CDC - Measles Cases and Outbreaks 
https://www.cdc.gov/measles/cases-outbreaks.html

Transmission and Immunity

1. Transmission is by respiratory droplets and the transmission can occur 2 days prior to symptoms until 4 days after the rash appears. The patient should be in respiratory isolation.
2. The illness may be transmitted even in the absence of person-to-person contact. The virus can remain infectious in the air for up to 2 hours
3. Mothers that are immune passively transmit antibodies transplacentally. This will last 4-6 months. Immunized mother may transfer less immunity than those who have had the natural disease.
4. Evidence of Immunity against measles is defined as meeting at least one of the below criteria:
   1. born before 1957
   2. physician documented disease
   3. immunized
   4. Laboratory evidence of immunity

Clinical Course

A child showing a day-four measles rash
https://en.wikipedia.org/wiki/Measles

• After an incubation period of 8-12 days, the initial symptom is a fever, sometimes to 40C.
• This is followed by the development of the three C’s: cough, conjunctivitis, and coryza.
• Koplik spots, an enanthem, characterized by white spots on a red base on the buccal mucosa, will develop during this period prior to the development of the exanthem

Koplik's spots in the mouth a child with measles, appearing as "grains of salt on a reddish background.
https://en.wikipedia.org/wiki/Koplik%27s_spots

• The exanthem (skin rash) begins on the head and moves caudally. It is a maculopapular rash that is often confluent and not pruritic. It may last for up to a week and fades in order of appearance. It may be hemorrhagic.
• Average time from exposure to rash is 14 days. 

• Individuals who have been immunized and have waning immunity, may have a milder disease. 

Complications

• Otitis and pneumonias that are of viral or secondary bacterial etiology
• Croup syndromes
• Gastroenteritis, including appendicitis-like symptoms secondary to obscuring of the appendiceal lumen by proliferating lymphoid tissue
• Encephalitis occurs in 1/1000 cases
• Subacute sclerosing panencephalitis (SSPE). This is a rare degenerative CNS disease that may occur years after the infection and presents with seizures, coma, and death
• Myocarditis

Differential Diagnosis

Usually distinguishable by the distinct clinical course but may be confused with enteroviral diseases, rubella, Streptococcal infections, drug reactions, and ricketsial diseases.

Diagnosis

• Clinical presentation, especially with recent international travel or exposure to person with febrile rash illness
• Laboratory confirmation testing includes measles-specific IgM antibody in serum and measles RNA PCR in a respiratory specimen or urine 

Vaccine

• MMR (measles, mumps and rubella combination vaccine) is an attenuated (weakened) live virus vaccine 
• Two doses are recommended: first dose at 12-15 months of age and second dose at 4-6 years.
  • 1 dose is approximately 93% effective at preventing measles. 2 doses is 97% effective
• Contraindicated in patients who
  • are severely immunocompromised
  • are pregnant
  • had a previous serious allergic reaction (e.g., anaphylaxis) to a previous dose of this vaccine or neomycin 
  • NOTE: Severe allergy to eggs is not a contraindication to receiving the vaccine
• HIV-positive individuals may be given MMR if not immune AND CD4+ T >200
• May be given to children 12 mo - 12 years of age simultaneously with the varicella vaccine (MMRV vaccine)
• May cause anergy to PPD that will last 1 month. May be given at the same time of PPD
• If given within 72 hours after exposure, may protect against the disease.
• During an outbreak of measles, vaccine may be given as early as 6 months of age.
• Adverse reactions
  • fever 7-12 days after vaccination
  • rarely, allergic or anaphylactic reactions

Treatment

• Supportive measures
• Antivirals have not been effective
• Patients in third world countries where Vitamin A deficiency is a problem, should receive Vitamin A.
• Following exposure: 
  • Individuals without evidence of immunity should be offered either MMR vaccine within 72hrs OR immunoglobulin (IG) within 6 days as post-exposure prophylaxis to potentially provide protection or alter the clinical course of disease
  • ​Individuals at risk for severe disease (<12 months of age, pregnant women without evidence of immunity, severely immunocompromised) should receive immunoglobulins (IG) within 6 days of exposure.
    • For infants 6 - 11 months, MMR vaccine may be given in place of IG, if administered within 72 hours of exposure

Patient Resources

• Top 4 Things Parents Need to Know about Measles

• How vaccines work (video)

• Measles: Make Sure Your Child Is Fully Immunized

References

1. 1997 Red Book
2. Adam HM and Fennelly GJ. Updates on Measles Vaccine. Pediatrics in Review. 1998 19:323a.
3. Fennelly GJ and Adam HM. Measles Vaccine. Pediatrics in Review. 1998; 19:178-179.
4. Gold, Eli. Almost Extinct Diseases: Measles, Mumps, Rubella, and Pertussis. Pediatrics in Review. April 1996.
5. Resnick SD. New Aspects of Exanthematous Diseases of Childhood. Dermatologic Clinics. 1997; 15(2):257-266.
6. Zendel, Joseph A. An Infant Who Has Fever and Rash. Pediatrics in Review. 2000; 21:105-107.
7. Mulholland E. Measles in the United States, 2006 NEJM Aug 3, 2006
8. Parker A. et al. Implications of a 2005 Mesles Outbreak in Indiana for Sustained Elimination of Measles in the United States. NEJM Aug 3, 2006
9. MMWR 2008 San Diego Outbreak
10. Measles.  Pediatrics in Review September 2007
11. Measles | Vaccination | CDC. https://www.cdc.gov/measles/vaccination.html. Published February 25, 2019. Accessed April 12, 2019.
12. Measles | Cases and Outbreaks | CDC. https://www.cdc.gov/measles/cases-outbreaks.html. Published April 8, 2019. Accessed April 12, 2019.
13. Measles: Clinical manifestations, diagnosis, treatment, and prevention - UpToDate

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