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Measles Outbreak

Measles Outbreak. Danae Bixler, MD, MPH. Steps of an Outbreak Investigation. Prepare for fieldwork. Establish the existence of an outbreak. Verify the diagnosis. Steps of an Outbreak Investigation. 4. Define and identify cases. Establish a case definition Identify and count cases

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Measles Outbreak

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  1. Measles Outbreak Danae Bixler, MD, MPH

  2. WVDHHR / BPH / OEHP / DSDC / IDEP

  3. Steps of an Outbreak Investigation • Prepare for fieldwork. • Establish the existence of an outbreak. • Verify the diagnosis. WVDHHR / BPH / OEHP / DSDC / IDEP

  4. 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. WVDHHR / BPH / OEHP / DSDC / IDEP

  5. 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. WVDHHR / BPH / OEHP / DSDC / IDEP

  6. WVDHHR / BPH / OEHP / DSDC / IDEP

  7. Step 1. • Prepare for Fieldwork • Accumulate knowledge, equipment, sample questionnaires, etc. • Anticipate employee health issues • Make travel and leave arrangements • Know your role in the investigation WVDHHR / BPH / OEHP / DSDC / IDEP

  8. 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 WVDHHR / BPH / OEHP / DSDC / IDEP

  9. WVDHHR / BPH / OEHP / DSDC / IDEP

  10. Measles Basics • Clinical WVDHHR / BPH / OEHP / DSDC / IDEP

  11. Measles Basics • Clinical • Prodrome: • Stepwise increase in fever up to 103-105 F • Followed by cough, coryza, conjunctivitis • Koplik’s spots • 1-2 days before rash to 1-2 days after rash • Punctate blue-white spots on red background WVDHHR / BPH / OEHP / DSDC / IDEP

  12. Measles Basics • Clinical(2) • Rash: maculopapular, begins at hairline, progresses downward • Blanch for first 3-4 days • Discrete => confluent • Fades in order of appearance • May desquamate WVDHHR / BPH / OEHP / DSDC / IDEP

  13. Measles Basics • Complications WVDHHR / BPH / OEHP / DSDC / IDEP

  14. Measles Basics • Complications • Diarrhea 8% • Otitis media 7% • Pneumonia 6% • Encephalitis 0.1% • Death 0.2% • Hospitalization 18% WVDHHR / BPH / OEHP / DSDC / IDEP

  15. Measles in Chicago, 1989MMWR, 1990; 39:317 • 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%) WVDHHR / BPH / OEHP / DSDC / IDEP

  16. Measles Basics • Reservoir • Transmission WVDHHR / BPH / OEHP / DSDC / IDEP

  17. 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 WVDHHR / BPH / OEHP / DSDC / IDEP

  18. Measles Basics • Incubation period WVDHHR / BPH / OEHP / DSDC / IDEP

  19. Measles Basics • Incubation period • Exposure to prodrome: • Average 10-12 days • Exposure to rash: • 7-18 days • Average 14 days WVDHHR / BPH / OEHP / DSDC / IDEP

  20. Measles Basics • Infectious period WVDHHR / BPH / OEHP / DSDC / IDEP

  21. Measles Basics • Infectious period • From 4 days prior to rash onset to 4 days after rash onset WVDHHR / BPH / OEHP / DSDC / IDEP

  22. Measles Basics • Control measures WVDHHR / BPH / OEHP / DSDC / IDEP

  23. 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 WVDHHR / BPH / OEHP / DSDC / IDEP

  24. WVDHHR / BPH / OEHP / DSDC / IDEP

  25. 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 WVDHHR / BPH / OEHP / DSDC / IDEP

  26. Jay S WVDHHR / BPH / OEHP / DSDC / IDEP

  27. Anything else you want to know ???????????

  28. 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 WVDHHR / BPH / OEHP / DSDC / IDEP

  29. WVDHHR / BPH / OEHP / DSDC / IDEP

  30. WVDHHR / BPH / OEHP / DSDC / IDEP

  31. Is this an outbreak?

  32. Step 2. • Establish the Existence of an Outbreak • For measles: 1 case = outbreak WVDHHR / BPH / OEHP / DSDC / IDEP

  33. 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 WVDHHR / BPH / OEHP / DSDC / IDEP

  34. What do you want to do now?

  35. Step 4 • Establish a case definition • Identify and count cases WVDHHR / BPH / OEHP / DSDC / IDEP

  36. Establish a Case Definition • Clinical case definition An illness characterized by all of the following: • A generalized maculopapular rash lasting > 3 days • A temperature > 101 F • Cough, coryza or conjunctivitis WVDHHR / BPH / OEHP / DSDC / IDEP

  37. 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 WVDHHR / BPH / OEHP / DSDC / IDEP

  38. 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. WVDHHR / BPH / OEHP / DSDC / IDEP

  39. The report on Jay S. arrives . . . WVDHHR / BPH / OEHP / DSDC / IDEP

  40. 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 WVDHHR / BPH / OEHP / DSDC / IDEP

  41. 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. WVDHHR / BPH / OEHP / DSDC / IDEP

  42. Step 4 • Establish a case definition • Identify and count cases WVDHHR / BPH / OEHP / DSDC / IDEP

  43. 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 WVDHHR / BPH / OEHP / DSDC / IDEP

  44. . . . Good surveillance pays off! WVDHHR / BPH / OEHP / DSDC / IDEP

  45. 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 WVDHHR / BPH / OEHP / DSDC / IDEP

  46. Peter M. WVDHHR / BPH / OEHP / DSDC / IDEP

  47. 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 WVDHHR / BPH / OEHP / DSDC / IDEP

  48. . . . Good surveillance really, really pays off! WVDHHR / BPH / OEHP / DSDC / IDEP

  49. Step 5. • Perform Descriptive Epidemiology • Person • Place • Time WVDHHR / BPH / OEHP / DSDC / IDEP

  50. Measles in Chicago, 1989MMWR, 1990; 39:317 • 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%) WVDHHR / BPH / OEHP / DSDC / IDEP

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