Chickenpox Outbreak

1

• Chickenpox Outbreak
• Berkeley County,
• West Virginia
• Raja S. Akhtar

2

• Case Scenario
• On October 8th, 2002 Berkeley County Health
  Department reported an outbreak of chickenpox in
  an elementary school.
• Total cases reported with chickenpox symptoms
• (fever and rash) 11
• Setting Elementary school K-6th grade (5-12
  yrs)
• Date of Onset of 1st case 10/8/02

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• Step 3
• Verify Diagnosis

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Step 3. Verify the diagnosis

• LHD interviewed parents and school nurse to
• gather more information to verify diagnosis
• Parents of 9 out of 11 kids interviewed
• All 9 kids had symptoms of varicella
• 5 kids previously vaccinated (had milder
• symptoms)
• 4 kids unvaccinated
• No lab testing done
• All self/clinically diagnosed

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Step 4

• a. Establish a case definition
• b. Identify and count cases

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Step 4a. Establish a case definition

• Clinical definition
• An illness with acute onset of diffuse
  (generalized)
• maculopapular rash without other-apparent cause.
• Laboratory findings
• Isolation of varicella-zoster-virus (VZV), or
• Direct flourescent antibody, (DFA), or polymerase
• chain reaction (PCR) tests, or Significant rise
  in
• serum varicella immunoglobulin G antibody level
  by
• any standard serological assay

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Step 4a. Establish a case definition

• Case Classification
• Probable A case that meets the clinical case
  definition, is not laboratory confirmed, and is
  not epidemiologically linked to another probable
  or confirmed case
• Confirmed A case that is laboratory confirmed or
  that meets the clinical case definition and is
  epidemiologically linked to a confirmed or a
  probable case
• Comments Two probable cases that are
  epidemiologically linked would be considered
  confirmed, even in the absence of laboratory
  confirmation

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Step 4b. Identify and count cases

• Total cases 11
• Total number of kids attending school 397
• Number Unvaccinated 198 (50)
• Number Vaccinated 83 (21)
• Number who had the disease in
• the past 116 (29)

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Step 9 10

• Implement Control Measures
• Communicate findings

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Step 9 10

• Chickenpox Control
• Isolate infected cases until lesions have
  crusted
• Letter to parents
• Inform about the outbreak.
• Educate parents to get varicella vaccine for
  their
• kids to prevent the disease (within 3 days,
  and
• possibly up to 5 days after exposure).
• Provide public information sheet on chickenpox

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Step 9 10

• Chickenpox Control
• Health alert for health care providers
• Informing them about the outbreak
• Educating them about the effectiveness of
  vaccine in preventing or modifying varicella
  severity if used within 3 days, and possibly 5
  days of exposure.
• Vaccine Delivery
• Arrange and maintain supply of vaccine with
  the help of the immunization program.

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