Virus

Measles

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Measles, Rubeola, Morbilli, First Viral Exanthem of childhood, Red Measles, Koplik Spots

  • Pathophysiology
  1. Genus: Morbillivirus
  2. Incubation: 8-12 days (from exposure to rash onset)
    1. Range: 7-18 days (rarely up to 21 days)
  3. Transmission
    1. Infectivity starts 4 days before symptoms and extends to 4 days after rash onset
    2. Droplets of nasopharyngeal secretions
    3. Highly contagious
      1. Affects 90% of susceptible household contacts
  • Epidemiology
  1. Sporadic outbreaks in teenagers and young adults
  2. Incidence: World
    1. Worldwide Measles deaths 150,000 per year, esp. in age <5 years old (600,000/year before year 2000)
  3. Incidence: U.S
    1. U.S. Cases in 1941: 894,000 cases
    2. U.S Cases before 1967
      1. Infected: 500,000 cases/year
      2. Hospitalized: 50,000 cases/year
      3. Deaths: 500 deaths/year
    3. U.S. Cases in 2000: 86 cases
    4. U.S. Cases in 2014: 667 cases (especially in California, Ohio, New York City)
      1. Reintroduced from endemic regions via international travel
      2. U.S. transmission is increased via unimmunized patients (failed herd immunity)
    5. U.S. Cases in 2017: 100 cases as of May 20, 2017
      1. Measles outbreak in Minnesota related to unimmunized Somali community
      2. Community had been convinced not to immunize based on false MMR Autism links
      3. http://www.npr.org/sections/health-shots/2017/05/03/526723028/autism-fears-fueling-minnesotas-measles-outbreak
    6. U.S. Cases in 2019
      1. So far, in only the first 3 months of 2019, there have been 387 Measles cases
  4. References
    1. CDC Measles Statistics
      1. https://www.cdc.gov/measles/cases-outbreaks.html
  • Symptoms
  1. Prodrome (precedes the rash by 2-3 days)
    1. Classic "3 C's"
      1. Severe Cough (dry, hacking)
      2. Coryza
      3. Conjunctivitis
    2. High Fever (up to 105 F or 40.5 C)
    3. Malaise
    4. Irritability
    5. Photophobia
  2. Koplik Spots in Mouth (3-4 days after start of prodrome)
  3. Erythematous maculupapular rash (3-5 days after start of prodrome)
    1. Rash spreads from forehead, behind the ears and neck
    2. Then spreads to trunk and then to extremities (1-2 days later)
    3. Patients are contagious 4 days prior to rash onset
    4. Other symptoms begin to decrease after rash onset (esp. after foot involvement)
    5. Rash resolves over the following 5-10 days, followed by Desquamation
  • Signs
  1. Koplik Spots (pathognomonic, 60-70% of cases)
    1. Grayish-white sand-like clustered dots
    2. Slight, reddish areolae that may be hemorrhagic with a bluish-white center
    3. Often opposite upper first and second molars
    4. My spread to involve any of Buccal mucosa, lips, Gingiva, Hard Palate
    5. May also affect the Conjunctiva, vaginal mucosa
  2. Fever (Onset with rash)
  3. Blotchy red-brown, maculopapular, Morbilliform rash
    1. Discrete red-brown Macules blanch with pressure
    2. Begins on forehead
    3. Spreads to face and neck, behind ears
    4. Spreads to trunk and extremities
    5. Palms and soles are affected in up to 50% of patients
  4. Cervical Lymphadenopathy
  • Labs
  • Measles Diagnosis
  1. Approach
    1. Measles clinical case definition (symptom criteria)
      1. Fever with Temperature >= 101°F (38.3°C) AND
      2. Cough, Coryza, or Conjunctivitis AND
      3. Generalized, maculopapular rash that lasts for at least 3 days
    2. Testing Indications
      1. Rash AND Fever AND 1 of 3 upper respiratory symptoms (Cough or Coryza or Conjunctivitis) OR
      2. Rash AND Fever alone if risk factors (known exposure or international travel in last 30 days)
    3. Resources
      1. When to Suspect and Test for Measles (Minnesota Department of Health)
        1. http://www.health.state.mn.us/divs/idepc/diseases/measles/hcp/whensuspect.pdf
  2. Measles PCR (blood, throat, nasal secretions or urine) - First Line Testing
    1. Testing at 0-5 days after rash onset
      1. Measles throat swab PCR
    2. Testing at 6-9 after rash onset
      1. Measles throat swab PCR and
      2. Measles urine PCR
  3. Measles Serology (IgG and IgM) - May be performed in addition to PCR
    1. Measles IgM is positive within first few days of rash onset (elevated for the first month)
  4. Older test modalities (where PCR not available)
    1. Viral culture of throat, nasal secretions or urine
  5. References
    1. Minnesota Department of Health Measles Lab Testing
      1. http://www.health.state.mn.us/divs/idepc/diseases/measles/hcp/index.html#lab
  • Labs
  • Other Testing
  1. Complete Blood Count
    1. Pancytopenia with Thrombocytopenia may occur in severe cases
    2. Leukopenia during prodrome
      1. Lymphocytes <2000 associated with worse prognosis
  2. Liver Function Tests
    1. Transaminases increase in Measles hepatitis
  3. Respiratory secretions
    1. Respiratory secretions with multinucleated giant cells
    2. Immunofluorescent staining of respiratory cells
  • Course
  1. Severity related to extent and confluence of the rash
  2. When rash reaches feet, clinical improvement has begun
  • Management
  1. Supportive care
  2. Suspected cases
    1. Contact local public health department (initiate testing, contact tracing)
    2. Exposure precautions in hospital
    3. Discharged patients should self quarantine until definitive diagnosis
  3. Prevent spread
    1. Patients should quarantine themselves at home
    2. Patients and their household contacts should use Airborne Isolation protection for at least 4 days after rash onset
  4. Immunocompromised patients
    1. Consider Ribavirin
    2. Immunocompromised patients should be isolated for the entire duration of Measles infection
  5. Children
    1. Vitamin A
      1. Decreases morbidity and mortality and is recommended by WHO for all children with Measles
  6. Exposed healthcare workers
    1. Non-immune healthcare workers should be off work from day 5 after first exposure to day 21 after last exposure
  • Complications
  1. Early Common Effects
    1. Otitis Media
    2. Diarrhea and Dehydration
  2. Early Severe Effects
    1. Severe disease with dehydration
    2. Pneumonitis
    3. Pneumonia (3-5% of young adults)
      1. May result directly from measles Pneumonia or from Bacterial superinfection
      2. Includes Interstitial Giant Cell
    4. Hepatitis
    5. Glomerulonephritis
    6. Myocarditis
    7. Encephalitis (1 per 1000 Measles cases)
      1. Onset 4-7 days after rash
      2. Presents with Seizures, lethargy, Altered Mental Status
      3. Exclude other causes of Meningitis and Encephalitis including Bacterial Meningitis
      4. Mortality: 10%
      5. Immune-mediated response
  3. Late Effects
    1. Subacute sclerosing panencephalitis (SSPE)
      1. Incidence: 8.5 cases per 1 million Measles cases
      2. Onset 7-10 years after Measles infection
      3. Presents with Dementia and neuromuscular disorders (e.g. Ataxia, Seizures)
  4. Mortality
    1. Developed countries: 1-2 deaths per 1000 Measles cases
    2. Developing countries: 1-2 deaths per 100 Measles cases
    3. Worldwide (2013): 145,700 deaths (400 per day or 16 per hour)
    4. Highest mortality in infants and young children and immunocompromised patients
    5. Mortality is also high in unimmunized pregnant women
  • Prevention
  1. Active Immunization
    1. See MMR Vaccine
    2. Very effective Vaccine (97% protective after 2 doses)
    3. MMR Vaccine is safe (many studies have shown no association with Autism)
    4. Avoid delaying MMR Vaccination (perform at scheduled time: 12-15 months and 4-6 years)
    5. Measles is the most contagious of the Vaccine preventable diseases (affects 90% of those exposed)
    6. Contraindications: Immunocompromised
    7. Adults born in U.S. before 1957 may be assumed immune
    8. Those who are immunized and still acquire Measles tend to have mild course and are less contagious
  2. Immunoglobulin post exposure (passive Immunization)
    1. Dose
      1. Gamma globulin: 0.25 ml/kg (MAX 15 ml)
    2. Indications (within 6 days of exposure)
      1. Infants <12 months old
        1. May instead use Measles Vaccine for ages 6-12 months for exposure within 72 hours
      2. Pregnant women without Measles immunity
      3. Close, prolonged patient contact without Measles immunity
      4. Tuberculosis
      5. Immunocompromised patients
  • Resources
  • References
  1. Baringa and Skolnik in Hirsch and Kaplan, Measles, UpToDate, accessed 1/28/2015
  2. Chen in Steele, Measles, Medscape EMedicine, accessed 1/28/2015
  3. Harrison and Ruttan (2019) Crit Dec Emerg Med 33(7): 3-12
  4. Wallace and Spangler in Herbert (2015) EM:Rap 15(2): 2-3