Measles Outbreak

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Measles Outbreak

• Paige Jordan RN, BSN
• Region II Epidemiologist

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Steps of an Outbreak Investigation

• Prepare for fieldwork.
• Establish the existence of an outbreak.
• Verify the diagnosis.

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Steps of an Outbreak Investigation

• 4. Define and identify cases.
• Establish a case definition
• Identify and count cases
• Perform descriptive epidemiology.
• Develop hypotheses.
• Evaluate hypotheses.

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Steps of an Outbreak Investigation (2)

• 8. As necessary, reconsider, refine hypotheses
  and execute additional studies
• Additional epidemiological studies
• Other types of studies laboratory,
  environmental
• Implement control and prevention measures.
• Communicate findings.

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Step 1.

• Prepare for Fieldwork
• Accumulate knowledge, equipment, sample
  questionnaires, etc.
• Anticipate employee health issues
• Know the Clinical Case Definition and Case
  Classification.
• Make travel and leave arrangements
• Know your role in the investigation

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Employee Health

• Interviewers must be immune
• Two doses of measles-containing vaccine one month
  apart on or after the first birthday OR
• Laboratory evidence or history of prior disease
• Birth before 1957
• consider 1 dose MMR if no history of disease or
  laboratory evidence of immunity

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Measles Basics

• Clinical

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Measles Basics

• Clinical
• Prodrome
• Stepwise increase in fever up to 103-105 F
• Followed by cough, coryza, conjunctivitis
• Kopliks spots
• 1-2 days before rash to 1-2 days after rash
• Punctate blue-white spots on red background

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Measles Basics

• Clinical(2)
• Rash maculopapular, begins at hairline,
  progresses downward
• Blanch for first 3-4 days
• Discrete gt confluent
• Fades in order of appearance
• May desquamate

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Measles Basics

• Complications

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Measles Basics

• Complications
• Diarrhea 8
• Otitis media 7
• Pneumonia 6
• Encephalitis 0.1
• Death 0.2
• Hospitalization 18

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Measles in Chicago, 1989MMWR, 1990 39317

• Cases 2232
• Hospitalization 755 (33.8)
• Diarrhea 340 (15.2)
• Pneumonia 186 (8.3)
• Otitis media 52 (2.3)
• Encephalitis 1 (0.04)
• Deaths 8 (0.36)

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Measles Basics

• Reservoir
• Transmission

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Measles Basics

• Reservoir
• Humans
• Transmission
• Person-to-person via droplets
• Airborne in closed area for up to 2 hours after a
  person with measles occupied the area

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Measles Basics

• Incubation period

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Measles Basics

• Incubation period
• Exposure to prodrome
• Average 10-12 days
• Exposure to rash
• 7-18 days
• Average 14 days

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Measles Basics

• Infectious period

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Measles Basics

• Infectious period
• From 4 days prior to rash onset to 4 days after
  rash onset

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Measles Basics

• Control measures

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Measles Basics

• Control measures
• Post-exposure vaccination within 72 hours
  provides protection
• MIG for immunosuppressed, pregnant or infants.
• In school or daycare
• exclude unless 2 doses of measles vaccine are
  documented
• In health care
• Exclude susceptibles from day 5 through day 21
  after exposure

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Jay S.

• 3 year old healthy male
• Onset of cold symptoms on 3/7/03 RX
  amoxicillin on 3/8 because of fever 105 F
• Rash onset 3/10/03
• Blood test negative for measles

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Jay S
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Anything else you want to know

• ???????????

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Step 2.

• Establish the Existence of an Outbreak
• Outbreak (epidemic) occurrence of more cases
  than expected in a given area or among a specific
  group of people over a particular period of time.
• Cluster aggregation of cases in a given area
  over a particular period without regard to
  whether the number is more than expected

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Is this an outbreak?

• YES or NO

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Step 2.

• Establish the Existence of an Outbreak
• Is this more than expected?
• For measles
• 1 case outbreak

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Step 3.

• Verify the diagnosis
• Typical clinical presentation
• Laboratory confirmation
• Isolation of measles virus (e.g., nasopharynx,
  urine)
• Significant rise in measles IgG by any standard
  serologic assay
• Positive serologic test for measles IgM

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What do you want to do now?
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Step 4

• Establish a case definition
• Identify and count cases

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Establish a Case Definition

• Clinical case definition
• Should include person, place and time.
• Should be consistant with established standards
  like CDC case definition.

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Establish case definition (cont.)

• Any person with the following symptoms that live
  in and around Huntington with an onset of the
  below symptoms in the past 2 weeks.
• An illness characterized by all of the following
• A generalized maculopapular rash lasting gt 3 days
• A temperature gt 101 F
• Cough, coryza or conjunctivitis

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Establish a Case Definition (2)

• Laboratory criteria for diagnosis
• Positive serologic test for measles
  immunoglobulin M (IgM) antibody, or
• Significant rise in measles antibody level by any
  standard serologic assay, or
• Isolation of measles virus from a clinical
  specimen

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Establish a Case Definition (3)

• Case Classification
• Suspected Febrile illness accompanied by
  generalized maculopapular rash
• Probable A case that meets the clinical case
  definition, has noncontributory or no serologic
  or virologic testing, and is not
  epidemiologically linked to a confirmed case
• Confirmed A case that is laboratory confirmed
  or that 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.

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The report on Jay S. arrives . . .
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Is Jay a case?

• 3 year old healthy male
• Onset of cold symptoms on 3/7/03 RX
  amoxicillin on 3/8 because of fever 105 F
• Rash onset 3/10/03
• Blood test negative for measles

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Is Jay a case?

• Case Classification
• Suspected Febrile illness accompanied by
  generalized maculopapular rash
• Probable A case that meets the clinical case
  definition, has noncontributory or no serologic
  or virologic testing, and is not
  epidemiologically linked to a confirmed case
• Confirmed A case that is laboratory confirmed
  or that 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.

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Is Jay a case?

• Case Classification
• Suspected Febrile illness accompanied by
  generalized maculopapular rash
• Probable A case that meets the clinical case
  definition, has noncontributory or no serologic
  or virologic testing, and is not
  epidemiologically linked to a confirmed case
• Confirmed A case that is laboratory confirmed
  or that 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.

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Step 4

• Establish a case definition
• Identify and count cases

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What type of surveillance would you like to do?

• Active surveillance
• Individually phone / visit health care providers
  to search for additional cases
• Enhanced passive surveillance
• Disseminate written request for reports of
  additional cases

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. . . Good surveillance pays off!
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Peter M.

• 7 ½ year old home-schooled previously healthy
  male
• Onset of runny nose, cough, fever of 104 on
  3/10/03
• Rash began on the forehead 3/13/03 progressed
  downward, now fading from the face
• Measles IgM () on 3/14/03

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Peter M.
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Is Peter M. a case?

• Onset of runny nose, cough, fever of 104 on
  3/10/03
• Rash began on the forehead 3/13/03 progressed
  downward, now fading from the face
• Measles IgM () on 3/14/03

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. . . Good surveillance really, really pays off!
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Step 5.

• Perform Descriptive Epidemiology
• Person
• Place
• Time

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Measles in Chicago, 1989MMWR, 1990 39317

• N 2,232
• Age
• Less than 5 1,663 (74.5)
• Less than 1 422 (18.9)
• Race / ethnicity
• Black 1,594 (71.4)
• Hispanics 506 (22.7)

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Measles in Chicago, 1989MMWR, 1990 39317

• N 2,232
• Vaccination status
• Unvaccinated 1,667 (74.7)
• Preschool children age 1-4 929 (41.6)
• Less than 16 months 731
• Less than 1 year of age 422
• Deaths 8
• N 7 in Children lt 5 years
• N 5 in Children lt 15 months

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Time to take a close look at these cases . . .
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Your conclusions

• 3 confirmed / probable cases
• Population at-risk
• preschool and early school-age with 0 or 1 doses
  of MMR
• in Cabell County
• No clustering within Cabell County
• Clustered in time

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Step 6, 7, 8

• 6.Develop hypotheses
• 7. Evaluate hypotheses
• 8. As necessary, reconsider/refine hypotheses,
  case definition and execute additional studies
• epidemiological
• other

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Step 9.

• Implement control measures EARLY!

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Measles control

• Vaccination (ideally within 72 hours of exposure)
• Two doses in population where measles is
  occurring, OR
• Exclude until 21 days after rash onset in the
  last case
• Measles immune globulin (within 6 days of
  exposure)
• Selected infants, pregnant women,
  immunocompromised persons

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Investigate . . .

• Forward
• Determine who is at-risk from exposure to these
  cases
• Implement control measures to prevent future
  cases
• Backward
• Identify where these cases originated
• Take action to prevent future exposures

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Teamwork Time

• What are your hypotheses?
• i.e., where did these cases come from?
• What kind of control measures do you want to
  implement?
• For whom?
• Other questions?

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Oh, and by the way . . . Jay S. is IgM ()
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Step 10.

• Communicate findings

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Step 10.

• Communicate findings
• 3 children with rash onset from 3/10 to 3/14
• Exposure to an unidentified index case around
  2/24 to 3/3
• Doctors offices notified
• Notify patients
• Exclude susceptible HCW day 5-21 after exposure
• Affected daycares
• Exclude children until 2 doses documented.

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THE END

• QUESTIONS???