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Danae Bixler, MD, MPH Division of Infectious Disease Epidemiology
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Objectives Describe 2009 outbreaks Lessons learned Prompt reporting Laboratory confirmation / diagnosis Outbreak investigation as problem-solving Types of common outbreaks Enteric outbreaks Rash illness ‘Other’ Vaccine preventable disease outbreaks Respiratory outbreaks Healthcare associated outbreaks Relate findings to the 13 steps of outbreak investigation. 2
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Steps of Outbreak Investigation 1. Prepare for field work 2. Establish the existence of an outbreak 3. Verify the diagnosis 4. Construct a working case definition 5. Find cases systematically and record information 6. Perform descriptive epidemiology 3
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Steps of Outbreak Investigation (2) 7. Develop hypotheses 8. Evaluate hypotheses epidemiologically 9. As necessary, reconsider, refine, and re-evaluate hypotheses 10. Compare and reconcile with laboratory and/or environmental studies 11. Implement control and prevention measures 12. Initiate or maintain surveillance 13. Communicate findings 4
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Summary Data (provisional) 123 outbreaks reported 98 (80%) confirmed as outbreaks or clusters 39 (71 %) counties reported one or more outbreak- related cases Jurisdiction 90 (92 %) West Virginia 3 (3 %) multi-state / West Virginia = lead investigator 4 (4 %) multi-state / other state = lead investigator 6
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Counties Reporting Outbreak-Related Cases (provisional / includes multi-county outbreaks) CountyNumber of Outbreaks Reported Kanawha16 Wood12 Mercer6 Putnam6 Fayette5 Raleigh4 Logan4 Marshall4 Monongalia4 Ohio4 Preston4 7
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Counties Reporting Outbreak-Related Cases (provisional / includes multi-county outbreaks) CountyNumber of Outbreaks Reported Cabell3 Mason3 Pleasants3 Randolph3 Roane3 Berkeley2 Gilmer2 Greenbrier2 Lewis2 Marion2 Monroe2 Wayne2 8
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Timeliness of Reporting – Summary Statistics (provisional) N = 85 observations (87 %) Mean 42 hours Median 1 hour Range = 0 to 662 hours 10
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Timely reporting of outbreaks Laboratory support Technical support Case definitions / diagnosis Descriptive epidemiology Cohort or case-control studies Communications support 11
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Timely reporting of outbreaks Required under: Reportable disease rule Threat preparedness funding stream Program plan 12
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Timeliness of Reporting (provisional / multi-county outbreaks excluded) Counties that report more than one outbreak reported outbreaks more rapidly: 13 Number of Outbreaks Reported Number of Outbreaks Mean Time elapsed (hours) Median Time elapsed (hours) > 166271 11311824
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Reported Outbreaks by Type, West Virginia, 2009 (provisional) Outbreak TypeFrequencyPercent Respiratory 5354% Enteric 2930% Rash 99% Other 77% Total 98100% 14
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2009 15
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Enteric Outbreak Summary (provisional) N = 29 Reported by 23 (42%) counties Jurisdiction: 24 (83%) West Virginia 1 (3%) multi-state; West Virginia = lead investigator 14 cases gastroenteritis N = 4 (14%) multi-state outbreaks; CDC / other state = lead 16
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West Virginia Enteric Outbreaks (provisional) 24 (83%) West Virginia enteric outbreaks 1 (4%)Salmonella enteritidis 22 (92%) Norovirus or acute gastroenteritis 18 (82%) in nursing homes / healthcare facilities 17 (77%) person-to-person transmission 1 (4%) rotavirus 17
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Norovirus NEJM, 2009; 361:1776 Acute onset vomiting and/or diarrhea Reservoir = humans Highly efficient transmission 18 – 1000 viral particles 30% secondary attack rate Droplets Fomites Person-to-person Environmental contamination 19
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Norovirus (2) NEJM, 2009; 361:1776 Viral shedding Precedes onset 30% After recovery (up to 8 weeks) Environmental stability 0° C to 60° C Surfaces Recreational and drinking water Food items such as raw oysters, fruits, vegetables Lack of long-term immunity Viral mutation 20
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Norovirus NEJM, 2009; 361:1776 Prevention and Control Isolation of ill persons Enforce personal hygiene Environmental decontamination Use of alcohol-based hand sanitizer promising 21
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Acute Gastroenteritis 1. Prepare for field work 2. Establish the existence of an outbreak 3. Verify the diagnosis 4. Construct a working case definition 5. Find cases systematically and record information 6. Perform descriptive epidemiology 7. Develop hypotheses 8. Evaluate hypotheses epidemiologically 9. As necessary, reconsider, refine, and re-evaluate hypotheses 10. Compare and reconcile with laboratory and/or environmental studies 11. Implement control and prevention measures 12. Initiate or maintain surveillance 13. Communicate findings 23
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Acute Gastroenteritis 2. Establish the existence of an outbreak 3. Verify the diagnosis. 4. Construct a working case definition 24
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Acute Gastroenteritis 2. Establish the existence of an outbreak 3. Verify the diagnosis. 4. Construct a working case definition 25
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26 6. Perform descriptive epidemiology.
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27 6. Perform descriptive epidemiology. 7. Develop hypotheses.
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Salmonella Bacterial cause of diarrhea, fever, abdominal cramps Most persons recover without treatment. Severe illness: Elderly Infants and young children Immunocompromised persons Multi-state outbreaks Widely distributed Commercial food products Produce Detection by pulse-net 30
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Multi-state Salmonella Outbreaks Pulsenet Send isolates to OLS for PFGE 2008 Salmonella typhimurium / peanut butter National update 2009 March: Salmonella typhimurium / Virginia April: Salmonella St. Paul / multistate June: Salmonella enteritidis / Virginia June: Salmonella oranienburg / Louisiana 31
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Salmonella typhimurium outbreak MMWR, 2009; 58:85-90. Nov 25, 2008 investigation started. Multiple institutional outbreaks … traceback demonstrated one common food: King Nut peanut butter Step 7: Develop hypotheses Case-control implicated peanut butter Step 8: Evaluate hypotheses epidemiologically. Jan 9, 2009, Minnesota Department of Agriculture isolated the outbreak strain from King Nut Peanut Butter. Step 10: Compare and reconcile with laboratory and/or environmental studies. 32
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Ongoing investigation MMWR, 2009; 58:85-90. Multiple institutional outbreaks … King Nut peanut butter was distributed to institutions. Many ill persons did not eat peanut butter in institutions. Step 9. As necessary, reconsider, refine and re-evaluate hypotheses. Second series of case-control studies: pre-packaged peanut butter crackers. Step 8: Evaluate hypotheses epidemiologically. Intact packages of crackers yielded the outbreak strain Step 10: Compare and reconcile with laboratory and/or environmental studies. 33
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34 MMWR, 2009; 58:85-90.
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35 MMWR, 2009; 58:85-90.
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36 Number of infections (N = 226*) with the outbreak strain of Salmonella Saintpaul associated with eating alfalfa sprouts, by date of illness onset --- United States, February--April 2009 * as of May 1, 2009 MMWR, 2009; 58:500-503
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Number of infections (N = 228*) with the outbreak strain of Salmonella Saintpaul, associated with eating alfalfa sprouts, by state --- United States, February--April 2009 *as May 1, 2009 MMWR, 2009; 58:500-503 37
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2009 38
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Rash Illness Outbreaks (provisional) 4 Human parvovirus B-19 (“Fifth Disease”) schools 3 scabies Nursing home Detention center Homeless shelter 2 varicella schools 39
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Erythema Infectiosum (Parvovirus B-19) (“Fifth Disease”) Mild prodrome Fever 15-30% ‘Slapped face’ rash Rash Symmetric, maculopapular, reticular, often pruritic Trunk Moves peripherally to arms, buttocks, thighs Fluctuates / recurs 40
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Parvovirus B-19 (“Fifth Disease”) 41
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Parvovirus B-19 (“Fifth Disease”) Hardin MD/University of Iowa and CDC http://www.lib.uiowa.edu/hardin/Md/cdc/fifthdisease/4507.html http://www.lib.uiowa.edu/hardin/Md/cdc/fifthdisease/4507.html 42
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Parvovirus B-19 adapted from 2009 Redbook ConditionsUsual Hosts Erythema InfectiosumHealthy children Polyneuropathy syndromeHealthy adults (female > male) Chronic anemia / pure red cell aplasia Immunocompromised adults Transient aplastic crisisPeople with hemolytic anemia (e.g., sickle cell) Hydrops fetalis / congenital anemia Fetus (1 st half of pregnancy) Persistent anemiaImmunocompromised people 43
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Parvovirus B-19 Erythema Infectiosum Transmission: contact with respiratory tract secretions Secondary spread 50% in household contacts 20% in school and daycare Infectious period Prior to rash onset No exclusion of children with rash 44
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Parvovirus B-19 Erythema Infectiosum Control Hand hygiene Dispose of tissues Counsel pregnant women Low risk Exclusion not recommended Evaluation per OB/GYN 45
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Parvovirus B-19 Outbreaks 1. Prepare for field work 2. Establish the existence of an outbreak 3. Verify the diagnosis 4. Construct a working case definition 5. Find cases systematically and record information 6. Perform descriptive epidemiology 7. Develop hypotheses 8. Evaluate hypotheses epidemiologically 9. As necessary, reconsider, refine, and re-evaluate hypotheses 10. Compare and reconcile with laboratory and/or environmental studies 11. Implement control and prevention measures 12. Initiate or maintain surveillance 13. Communicate findings 46
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Scabies Cleaveland Clinic J Med, 2008; 75:474-478. Papules Excoriations Burrows Nodules 47
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Atypical Scabies N Engl J Med, 2006; 345:1718-27. 48
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Management of Scabies Outbreaks Nosocomial / institutional outbreaks: Contact precautions 24 hours after treatment 10 days after treatment of crusted scabies Make a secure diagnosis Consider dermatology consultation Identify infested persons Treat infested persons and contacts Patients and staff Environmental control measures 49
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Environmental Management of Scabies Infestation (CDC) WhatUsed by WhomManagement Items used within 3 days: Bedding Clothing Towels Infested person Household and sexual contacts Persons with skin-to-skin contact Wash in hot water and dry in a hot dryer OR Dry clean OR Seal in a plastic bag for at least 72 hours Insecticide sprays and fumigants NOT recommended Mites do not survive more than 3 days away from human skin 50
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Scabies Outbreaks 1. Prepare for field work 2. Establish the existence of an outbreak 3. Verify the diagnosis 4. Construct a working case definition 5. Find cases systematically and record information 6. Perform descriptive epidemiology 7. Develop hypotheses 8. Evaluate hypotheses epidemiologically 9. As necessary, reconsider, refine, and re-evaluate hypotheses 10. Compare and reconcile with laboratory and/or environmental studies 11. Implement control and prevention measures 12. Initiate or maintain surveillance 13. Communicate findings 51
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2009 52
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Other Outbreaks (provisional) Invasive methicillin sensitive Staphylococcus aureus Healthcare associated Hepatitis B Healthcare associated 2 Conjunctivitis Nursing home Elementary school 1 skin infection Day care 2 MRSA Nursing home Football team 53
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Conclusions Prompt reporting of outbreaks Assistance with: Laboratory diagnosis Clinical diagnosis Control measures Required by/for: Reportable disease rule Program plan Threat preparedness 54
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Lessons Learned Outbreak investigation process Problem-solving Establish the existence of an outbreak … Verify the diagnosis … Control measures … Communicate findings … Laboratory confirmation Collaboration between local, regional, state … CDC … WHO Stay tuned: Salmonella enteritidis Healthcare associated outbreaks Respiratory outbreaks Varicella 55
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