Public Health Information Network PHIN Series II

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Public Health Information Network (PHIN) Series
II

• Outbreak Investigation Methods
• From Mystery to Mastery

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(No Transcript)
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Series II Sessions
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Access Series Files Online http//www.vdh.virgini
a.gov/EPR/Training.asp

• Session slides
• Session activities (when applicable)
• Session evaluation forms
• Speaker biographies

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Site Sign-in Sheet

• Please submit your site sign-in sheet and
• session evaluation forms to
• Suzi Silverstein
• Director, Education and Training
• Emergency Preparedness Response Programs
• FAX (804) 225 - 3888

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Series IISession I

• Recognizing an Outbreak

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Session Overview

• Introduction to surveillance
• Steps of an outbreak investigation
• Foodborne disease surveillance
• Case study investigated by Epi Team
  professionals
• a. Epidemiologists
• b. Public Health Laboratory specialists
• c. Environmental Health specialists

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Todays Presenters

• Amy Nelson, PhD, MPH
• Consultant, NCCPHP
• Ron Holdway
• Environmental Health Director,
• Orange County Health Department, NC
• Sarah Pfau, MPH
• Moderator

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Recognizing an OutbreakLearning Objectives

• Identify multiple types of foodborne illness
  surveillance systems
• Recognize uses of surveillance data
• Identify steps of an outbreak investigation

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Recognizing an OutbreakLearning Objectives
(contd.)

• Develop and use a case definition
• Apply the process of case finding in an outbreak
• Generate a leading hypothesis

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Surveillance
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What is Public Health Surveillance?

• The ongoing, systematic collection, analysis,
• and interpretation of health-related data
• essential to the planning, implementation, and
• evaluation of public health practice, closely
• integrated with the timely dissemination of these
  
• data to those responsible for prevention and
• control
• - CDC

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• Surveillance drives the cycle of public health
  prevention

Surveillance
Epidemiologic investigation
Prevention measures
Applied Targeted Research
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Purpose of Surveillance

• Assess public health status
• Define public health priorities
• Evaluate programs
• Stimulate research

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Surveillance Priority Areas

• Frequency
• Severity
• Cost
• Preventability
• Communicability
• Public interest

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Surveillance Applications

• Estimate the magnitude of the problem
• Determine the geographic distribution of illness
• Portray the natural history of a disease
• Detect epidemics / define a problem
• Generate hypotheses, stimulate research
• Evaluate control measures
• Monitor changes in infectious agents
• Detect changes in health practice
• Facilitate planning

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VA Reportable Diseases
http//www.vdh.state.va.us/epi/list.asp
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Estimate the Magnitude of the ProblemFoodborne
disease cases reported in 2003 in VA
Based on 2000 U.S. Census data, per 10,000
people
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Determine the Geographic Distribution of Illness
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Portray the Natural History of a Disease
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Detect Epidemics / Define a Problem

• Identify baseline for disease
• Compare increase with baseline
• Eyeball, experience
• CUSUM statistical methods
• Emerging Infect Dis. 1997 3(3) 395-400

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Underreporting in Surveillance

• Surveillance data may represent the tip of the
  iceberg
• True burden of disease depends on several factors
• Clinical symptoms
• Medical care seeking behavior
• Diagnosis
• Reporting

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Types of Surveillance

• Active vs. passive
• Clinician vs. laboratory

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Outbreak Surveillance Sources

• Laboratory-confirmed reports of notifiable
  diseases
• Clinician reports of notifiable disease
• Concerned parent/citizen reports to health
  department
• Media

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Archived VA PHIN SessionSurveillance

• http//www.vdh.virginia.gov/EPR/Training.asp
• Introduction to Public Health Surveillance
• Federal Public Health Surveillance
• Techniques for Review and Analysis of
  Surveillance Data

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Outbreak Investigation
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Why Investigate?

• Increase detected through surveillance
• Characterize the problem
• Prevention and control
• Research and answer scientific questions
• Train epidemiologists
• Political / legal concerns

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CDC Guidelines for Systematic Investigations

• Verify diagnosis
• Confirm epidemic
• Identify and count cases (define)
• Tabulate and orient data time, place, person
• Take immediate control measures

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CDC Guidelines for Systematic Investigations
(contd.)

• Initiate surveillance
• Formulate and test hypothesis
• Refine hypothesis
• Plan additional studies
• Implement and evaluate control measures
• Communicate findings

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Exceptions to the Rule

• CDC guidelines provide a model for systematic
  outbreak investigations.
• No two outbreaks are alike!
• Steps of an outbreak could
• occur in a different order
• occur simultaneously
• be repeated after new information is discovered

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Question and AnswerOpportunity
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5 minute break
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Case Study

• The case study that will be used in todays
  session is based on an outbreak that occurred in
  Austin, Texas in 1998.

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Case Study

• Today we will review parts of the case study
  that illustrate how to
• Develop and use a case definition
• Apply the process of case finding in detecting an
  outbreak
• Verify the diagnosis and
• Follow methods for generating a hypothesis.

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Case Study

• Disease Surveillance

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Disease Surveillance

• On the morning of March 11,1998, the
• Texas Department of Health (TDH) received
• a telephone call from a male student at a
• nearby university

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Disease Surveillance

• Student and his roommate were suffering from
  nausea, vomiting, and diarrhea
• Both had become ill during the night
• The roommate had taken medication
• Neither student sought medical care
• Both students believed a local pizzeria the
  previous night was responsible
• Students asked if they should go to class/take
  midterm exam that afternoon

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Disease Surveillance Case Report

• What questions would you ask the student?
• WHO other ill persons age, sex, symptoms, and
  whether they sought care
• WHAT physical condition, symptoms, medication,
  and medical care sought
• WHEN when did the affected become ill
• WHERE city/school, address, telephone number of
  ill persons
• WHY/HOW suspected cause of illness, risk
  factors, modes of transmission, hints from those
  who did not become ill

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Case ReportWho / Where
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Case ReportWhat
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Case ReportWhen / How

• Student refused to provide food history beyond
  foods
• eaten at local pizzeria
• He and his roommate shared no other meals in
  the last 72
• hours
• They ate separately at the University cafeteria

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Activity 110 minutes

• Draft Case Report
• Interview Questions

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Activity 1 Possible Questions

• WHO How old are you?
• WHAT What symptoms do you have?
• WHEN What was the first day you began feeling
  these symptoms?
• WHERE Besides your home, please name each place
  that you spend time on a regular basis (such as
  work, school, or another establishment)
• WHY / HOW Lets go through all of the foods and
  beverages that you have eaten recently, starting
  with yesterday. What did you have to eat or
  drink for breakfast yesterday morning?

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Disease Surveillance Advice to the Caller

• What do you advise the student about attending
  classes that day?
• Refer to personal clinician or student health
  center for evaluation
• If asymptomatic, can return to normal activities
• Food handler?
• Work with high risk populations?

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Disease SurveillanceWhat next?

• File the report and stop?
• Investigate further?

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Deciding to Investigate

• Ideally, all reports of possible food borne
  outbreaks should be investigated to
• Prevent other persons from becoming ill
• Identify potentially problematic food handling
  practices
• Add to the knowledge of food borne diseases

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Maybe you should...

• If a severe (life-threatening) illness
• If there are confirmed clusters/large numbers of
  a similar illness
• If food borne illness is in a food-handler
• If association with a commercially distributed
  food

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Deciding Not to Investigate

• Cant investigate everything
• Often must choose the highest priority
• Outside pressure to investigate (media,
  politicians)

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Maybe you shouldnt...

• If signs/symptoms or confirmed diagnoses among
  the affected suggest they might not have the same
  illness
• If ill persons are not able to provide adequate
  information for investigation, including date and
  time of onset of illness, symptoms, or a complete
  food history

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Maybe you shouldnt...

• If confirmed diagnosis and/or clinical symptoms
  are not consistent with the foods eaten and the
  onset of illness
• If there are repeated complaints made by the same
  individual(s) for which prior investigations
  revealed no significant findings

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Case Study

• Case Finding

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Case Definition

• To verify the existence of an outbreak, you must
  establish that a higher number of cases than
  expected is occurring.

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Case Definition

• A standard set of criteria for deciding whether
  an individual should be classified as having the
  disease of interest, including
• Clinical criteria (signs, symptoms, and
  laboratory tests)
• Restrictions on person, place, and time

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Case Definition

• The case definition can be modified as more data
  are obtained
• Do not include the hypothesis being tested in the
  case definition

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TX Case StudyCase Definition

• Initial Case Definition
• University student with diarrhea and vomiting
  in the previous 24 hours

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Activity 2

• Develop a Case Definition

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Activity 2 Case Definition

• Cases are adults living in Jonesville, USA,
  diagnosed with laboratory confirmed E. coli
  0157H7 at the end of October, or having symptoms
  (abdominal cramping, bloody diarrhea) compatible
  with this diagnosis at this time without
  laboratory confirmation.

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Case Finding Using the Case Definition

• Look for more cases (student health center,
  hospitals, clinicians, dorm rooms) to determine
  the extent of the potential outbreak

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Case Finding

• The pizzeria where the student and roommate had
  eaten was closed until 1100 A.M.
• There was no answer at the University Student
  Health Center (left a message on the answering
  machine)

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Case Finding

• A call to the emergency room at a local hospital
  revealed that 23 university students had been
  seen for acute gastroenteritis in the last 24
  hours
• In contrast, only three patients had been seen at
  the emergency room for similar symptoms from
  March 5-9, none of whom were associated with the
  university

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Case Finding

• At 1030 A.M., a student health center physician
  returned the call and reported that 20 students
  with vomiting and diarrhea had been seen the
  previous day (no stool specimens were collected)
• The physician reported that 1-2 students per week
  typically would have been seen for these symptoms

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Outbreak Detection Is This an Outbreak?

• Definition of an outbreak
• The occurrence of more cases of a disease than
  expected for a particular place and time
• Expected of cases 5 per week
• Actual of cases 40 per day
• Outbreak detected?
• Yes!

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Prospective Case Finding

• TDH staff asked local health care providers to
  report cases of vomiting or diarrhea seen since
  March 5 at the
• University Student Health Center
• Hospital A emergency room
• Emergency departments at six other hospitals
  located in the general vicinity
• Health care providers were asked to collect stool
  specimens from any new cases

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Case FindingDescriptive Epidemiology

• Afternoon of March 11, TDH staff visited the
  emergency room at Hospital A and reviewed medical
  records of patients seen for vomiting and/or
  diarrhea since March 5
• Symptoms among 23 university students seen
  included
• Oral temperatures ranged from 98.8/F (37.1/C) to
  102.4/F (39.1/C)
• Complete blood counts showed an increase in white
  blood cells (n10)

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Symptom Profile
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Case Study

• Verify the Diagnosis

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Verify the Diagnosis Microbiology

• What broad categories of diseases might be
  causing the outbreak?
• Enteric viruses
• Bacteria
• Parasites
• Toxins
• Stool specimens had been submitted for routine
  bacterial pathogens, but no results were
  available

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Verify the Diagnosis Microbiology

• A TDH staff person was designated to help the
  facilities identify and report cases
• Bacterial cultures from patients seen in the
  emergency rooms were performed at the collecting
  hospital and confirmed at the TDH Laboratory
• Specimens collected by the Student Health Center
  were cultured at the TDH Laboratory

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Verify the Diagnosis Potential Enteric Agents
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Verify the Diagnosis Find Plausible Agents

• Evaluate
• Predominant signs and symptoms
• Incubation period
• Duration of symptoms
• Suspected food
• Laboratory testing of stool, blood, or vomitus

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Verify the Diagnosis Find Plausible Agents

• Pathogen identification will help identify the
  potential incubation period
• Crucial to know the incubation period for
  hypothesis generation
• Dont need to wait for laboratory diagnosis to
  proceed

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Epidemiological Profiling
Epidemiol Infect. 2001127381-7
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Epidemiological Profiling

• Case Study chart review results (N23)
• Vomiting 90
• Fever 67
• Vomiting / Fever 1.34
• Median duration 39 hours

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Epidemiological Profiling

• Kaplan criteria for Norovirus outbreak
• Incubation period 24 to 48 hrs
• Duration of illness 12 to 60 hrs
• Vomiting gt50 of cases
• Modified to include vomiting/fever gt 1.0
• Negative for other pathogens

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Epidemiological Profiling
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Pathogen IdentificationResource

• CDCs Foodborne Outbreak Response and
  Surveillance Unit
• Guide to Confirming the Diagnosis in Foodborne
  Diseases
• http//www.cdc.gov/foodborneoutbreaks/guide_fd.htm
  

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Pathogen Identification
http//www.cdc.gov/foodborneoutbreaks/guide_fd
.htm
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NOROVIRUSES

• Norwalk Virus
• Group of related,
• SS RNA non-
• enveloped viruses
• Cause acute gastro-
• enteritis in humans

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NOROVIRUSES

• The estimated total cases of Norovirus infection
  is 23,000,000 in the U.S. per year.
• Approximately 40 of Norovirus infections are
  food borne.
• Noroviruses are responsible for 67 of the total
  food borne infections, 32 of the
  hospitalizations and 7 of the deaths.

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Clinical Presentation

• Incubation period is usually 24-48 hours
• Acute onset vomiting
• Watery, non-bloody diarrhea with abdominal cramps
• Nausea
• Low-grade fever may occur

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Clinical Presentation (Cont)

• Dehydration is the most common complication,
  especially among the young and the elderly
• Symptoms usually last between 24 to 60 hours
• Recovery is usually complete and there is no
  evidence of long term complications
• Asymptomatic infection may occur in as many as
  30 of the infected

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Treatment and Management

• No specific therapy exists for viral
  gastroenteritis
• Standard symptomatic therapy consists of
  replacing fluid losses and correcting electrolyte
  imbalances through oral and intravenous fluid
  administration

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Virus Transmission

• Noroviruses are transmitted primarily through the
  fecal-oral route via fecally contaminated food or
  water or by direct person-to-person spread
• Fomite contamination may also act as a source of
  infection
• Aerosolization of vomitus may spread the virus
  but not through the respiratory system

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Virus Transmission (Cont)

• Noroviruses are highly contagious an inoculum
  of as few as 10 viral particles may be sufficient
• Shedding usually begins with the onset of
  symptoms (although there may be some pre-symptom
  shedding) and may continue for two weeks after
  recovery

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Specimen Collection

• Human Identification can best be made from stool
  specimens taken within 48-72 hours after the
  onset of symptoms. Vomitus and serum may also be
  collected and tested
• Environmental Food and water samples can be
  collected and tested. Water samples should be
  filtered to increase the concentration of virus
  present
• Not part of the routine lab culture work-up for
  gastroenteritis

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Forensic Specimens

• Public health specimens as evidence in criminal
  investigations
• Samples taken as part of a legitimate
  investigation of an outbreak or other public
  health situation may be used in a criminal
  investigation
• Chain of custody form documenting dates and
  person / entities having the evidence (specimen)
  in their custody (i.e. for collection or
  transport)

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Prevention

• Prevention is based on
• The provision of safe food and water
• Correct handling of cold foods
• Frequent hand washing
• Paid sick leave

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Case Study

• Back to Verifying the Diagnosis. . .

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Verify the Diagnosis Culture Results

• Later in the afternoon of March 11th, culture
• results from 17 ill students became available

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Verify the Diagnosis Culture Results

• Results were primarily from the emergency room at
  Hospital A on March 10
• Results did not identify Salmonella, Shigella,
  Campylobacter, Vibrio, Listeria, Yersinia,
  Escherichia coli O157H7, Bacillus cereus, or
  Staphylococcus aureus
• Some specimens were positive for fecal leukocytes
  and fecal occult blood

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Microbiology DiagnosisInterpretation of Results

• What do these results mean, and what
• questions do they raise?

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Microbiology DiagnosisInterpretation of Results

• Potential reasons for negative results
• Mishandling of specimen resulting in death of the
  pathogen (during storage, transport, processing,
  or culture)
• Specimens collected too late in the illness
• Illness could be due to a bacteria not tested
  for, or due to a non-bacterial agent

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Case Study

• Hypothesis Generation

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Hypothesis Generation

• Day 2 (March 12)
• 75 persons with vomiting or diarrhea reported
• All were university students who lived on campus
• No cases among faculty or staff, or locals
• Median patient age 19 years (range 18-22)
• 69 were freshman
• 62 were female

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Hypothesis GenerationLine Listing

• This line listing has been sorted on the Age
  data field.

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Hypothesis GenerationEpidemic Curve
Viral incubation Average 24-48 hours
Range 1 7 days
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Hypothesis GenerationMeet with University
Officials

• Negotiate cooperation with the university
  officials
• Inform, update, plan, and coordinate

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Hypothesis GenerationMeet with University
Officials

• Collect information that might provide insights
  into the source of the outbreak, including
• Characteristics of the student body
• Sources of food/water, dining establishments
• Possible contact with animals through classes
• Student living arrangements

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Hypothesis Generation Information Collected

• The university is located in a small Texas town
  with a population of 27,354
• Enrollment of approximately 12,000 students
• 2,386 students live on campus
• 36 residential halls on the 200 acre main campus
• Most enrolled in on-campus meal plan
• About 75 of the students are Texas residents

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Hypothesis GenerationInformation Collected

• The university uses municipal water and sewage
  services
• There have been no breaks or work on water or
  sewage lines in the past year
• There has been no recent road work or digging
  around campus

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Hypothesis GenerationInformation Collected

• Main cafeteria
• Used by most on campus students
• Serves hot entrees, as well as items from the
  grill, deli bar, and a salad bar

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Hypothesis GenerationInformation Collected

• Smaller cafeteria
• Used by students who live off campus and
  university staff
• Also serves hot entrees, grilled foods, and a
  salad bar, but has no deli bar
• Offers menu selections with a per item cost
• Accessible to meal plan members

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Hypothesis GenerationInformation Collected

• Both cafeterias under same management
• Also about half a dozen fast food places on
  campus

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Hypothesis GenerationInformation Collected

• Spring break begins on March 13, at which time
  all dining services will cease until March 23
• Many students will leave town during the break,
  but about 25 of those living on campus will
  remain

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Hypothesis GenerationCase Interviews

• Hypothesis generating interviews were done with
  seven of the earliest case-patients reported by
  the ER and student health center

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Hypothesis Generation Case Interviews

• All 7 cases had onset of illness on March 10
• Four were male and three were female
• All but one was a freshman
• Two students were psychology majors one each was
  majoring in English and animal husbandry. Three
  students were undecided

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Hypothesis Generation Case Interviews

• Except for the psychology majors, none of the
  other students shared any classes
• Only one student had a roommate with a similar
  illness
• Lived in five different residential halls

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Hypothesis Generation Case Interviews

• Five students belonged to a sorority or a
  fraternity
• Three students had attended an all school mixer
  on March 6, the Friday before the outbreak began

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Hypothesis Generation Case Interviews

• Two students went to an all night science fiction
  film festival at one of the dorms on March 7
• Students reported attendance at no other special
  events most had been studying for midterm exams
  for most of the weekend

110
Hypothesis Generation Case Interviews

• Seven day food history
• All reported eating most of their meals at the
  universitys main cafeteria
• All but one student had eaten food from the deli
  bar
• Two had eaten food from the salad bar
• Three from the grill
• Only one had eaten food from the pizzeria
• No particular food item that was common to all or
  most of the students

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Hypothesis Generation
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Hypothesis Generation

• What are your leading hypotheses for the cause of
  the outbreak?
• Consider
• Pathogen
• Mode of transmission
• Source of outbreak
• Time period of interest (incubation)

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Hypothesis Generation1. Pathogen

• Signs and symptoms (vomiting, diarrhea, fever,
  bloody stools, fecal leucocytes, and fecal occult
  blood) consistent with acute gastrointestinal
  infection
• Negative bacterial cultures suggest a viral or
  parasitic pathogen
• Symptoms more consistent with virus

114
Hypothesis Generation1. Pathogen
Epi Curve suggests a point source outbreak and
short exposure period More consistent with a
virus than parasite
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Hypothesis Generation 2. Mode of Transmission

• Illness is limited to students living on campus
• Lack of illness in community, faculty, suggests
  city or university water systems not affected

116
Hypothesis Generation 2. Mode of Transmission

• Not spread person-to-person
• Cases did not cluster by dorm or classes
• All 7 students ate at university main cafeteria
  and deli bar
• Not used by off-campus students or faculty

117
Hypothesis Generation 3. Source

• No common food items identified among 7 students
• Viral agents are commonly transmitted through
• Sandwiches
• Salads
• Raw / undercooked shellfish

118
Hypothesis Generation 4. Period of Interest

• Viral gastroenteritis
• Incubation ranges lt1day to 7 days
• Majority of onset
• March 10 12
• Likely exposure period
• March 5 10
• (lt1 to 7 days before case onset)

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Hypothesis Generation

• Leading Hypothesis
• Viral infection spread by a food or beverage
  served at the university main cafeteria between
  March 5 and March 10

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Activity 3

• Generate a Leading Hypothesis

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Activity 3 Leading Hypothesis

• Option B is correct
• Exposure to E. coli O157H7 occurred through
  juice served at the local gym in late October.

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What Next?

• Have you proven your hypothesis?
• No!
• Information suggests, but does not prove, that
  the cause of the outbreak was in the main
  cafeteria
• Can control measures be taken?
• Not yet

123
What Next?

• Next Steps
• Environmental investigation
• Conduct a controlled study

124
Case Study

• Back to the Texas case study environmental
  investigation. . .

125
Environmental InvestigationConduct Interviews

• TDH environmental sanitarians inspected the main
  cafeteria and interviewed staff on March 12
• Except for one employee who worked at the deli
  bar and declined to be interviewed, all dining
  service personnel were interviewed

126
Environmental InvestigationFood Handler
Interviews

• Topics to cover
• Food items served during the implicated time
  period
• Illness among staff or their family members
  during the time period
• Hygienic practices and hand washing facilities
• Stool specimens from food handlers

127
Environmental InvestigationFood Handler
Interviews

• Topics to cover
• Watch/reconstruct food preparation/ handling
  practices performed during the time period
• Which staff were responsible for what during the
  time period
• Recipes for food items served, ingredients and
  their sources

128
Environmental Investigation Food Handler
Interview Results

• Thirty-one staff members were employed at the
  cafeteria
• 24 (77) were food handlers
• No food handlers interviewed reported being ill
  in the last two weeks
• Stool cultures were requested from all cafeteria
  staff

129
Environmental InvestigationFood Handling
Practices Observed

• In the cafeteria, the deli bar had its own
  preparation area and refrigerator
• Sandwiches were made to order by a food handler
• Newly prepared deli meats, cheeses, and
  condiments were added to partially depleted deli
  bar items from the day before (without discarding
  leftover food items)
• While the deli was open, sandwich ingredients
  were not kept refrigerated. The deli bar
  containers were not routinely cleaned

130
Environmental Investigation Sampling

• Samples of leftover food, water, and ice were
  collected

131
Environmental InvestigationEvidence-Based
Decision

• By dinner on March 12, the City Health
• Department closed the deli bar

132
Environmental InvestigationPoints to Consider

• Do you agree with the decision to close the deli
  bar?
• Circumstantial evidence only
• Many unsafe practices identified
• What do you think the next step should be?

133
Todays Conclusions

• We detected an outbreak of viral gastroenteritis
• We developed a leading hypothesis with the main
  campus cafeteria as the suspect

134
Question and AnswerOpportunity
135
5 minute break
136
Environmental Investigation

• Ron Holdway
• Environmental Health Director Orange County
  Health Department, North Carolina

137
ORANGE COUNTY HEALTH DEPARTMENTDR. ROSEMARY
SUMMERS, DIRECTOR

• ENVIRONMENTAL HEALTH DIVISION

138
ORANGE COUNTY HEALTH DEPARTMENT
THE NOROVIRUS OUTBREAK AT THE UNIVERSITY OF NORTH
CAROLINA January 2004
139
The UNC Outbreak

• Background
• Questions and Issues
• Environmental Investigation and Control Measures
• Final Analysis / Results

140
The UNC Outbreak

• Background

141
The UNC OutbreakBackground

• Call from UNC Student Health on January 21st AM
• A few cases (4-6) presented on 1-20
• Many more (50-60) presented on 1-21
• OCHD Epi Team convened at UNC SHS office

142
The UNC OutbreakBackground

• Epi Team Work on 1-21
• Understanding of situation (easier said than
  done!)
• Met with UNC SHS and EHS representatives
• Met with food service representatives
• Consulted with State epi representatives
• Alert/query to private providers in the community
• Outbreak (epidemic) or not? (YES!)
• Limited to UNC universe? (Yes)
• Case definition

143
The UNC OutbreakBackground

• Epi Team Work on 1-21 (cont.)
• Possible agents and transmission modes
• Questionnaire development testing
• Administer questionnaire (began that night around
  8pm after testing)
• Implemented general control measures
• Interviews with press representatives
• Some food samples
• At least one vomitus sample

144
The UNC OutbreakBackground

• Case Definition
• A UNC student with an acute episode of nausea,
  vomiting and/or diarrhea with onset on or after
  6PM on 1-20-04

145
The UNC OutbreakBackground

• Possible Agents
• Based on signs, symptoms and those that occur
  first or predominate - vomiting was occurring
  first and appeared to be predominating in this
  outbreak
• Sudden or gradual increase in cases?

146
The UNC OutbreakBackground

• Possible Agents (cont.)
• Among those considered for this outbreak
• Bacillus cereus toxin
• Staphylococcal aureus toxin
• Norovirus
• Metal or other elemental poisoning
• Fish and shellfish toxins

147
The UNC Outbreak

• Questions and Issues

148
The UNC OutbreakQuestions and Issues

• Point source or not?
• Contained to UNC?
• Intentional?
• Questionnaire and study
• Snow storm during event

149
The UNC OutbreakQuestions and Issues

• Point Source or Not?
• Time, place, person associations
• Epi curve(s) - we reviewed the numbers of cases
  at least daily
• Surveillance and disease presence in the general
  population
• ED
• Private providers
• PHRST Team

150
The UNC OutbreakQuestions and Issues

• Intentional?
• Dont discount until investigation and analyses
  are complete
• Even then . . . there is the case from The
  Dalles, Oregon
• Many agents arent conducive to intentional
  releases
• Considered but discounted for this outbreak

151
The UNC OutbreakQuestionnaire and Study

• Case-control study
• Obtain well interviews from sick contacts (room
  mates, suite mates, etc.)
• Initial software was spreadsheet, but was changed
  to Epi Info

152
The UNC OutbreakQuestionnaire and Study

• Food histories (at least 48 hours prior) -
  on-campus and off
• Contacts
• Other environmental exposures
• Vomitus
• Dorms
• Travel
• Swimming pools

153
The UNC OutbreakQuestionnaire and Study

• Obstacles, Problems and Lessons Learned
• Vast array of foods at UNC dining halls
• Study was designed to get controls from contacts
  of sick - this approach was flawed
• Data from multiple inputs stations could not be
  merged by OCHD - problem finally solved by Drew
  Voetsch

154
The UNC Outbreak

• Environmental Investigation and Control Measures
• (Those used or considered)

155
The UNC OutbreakEnvironmental Investigation and
Control Measures

• Dorm sweeps
• Interviews
• SHS waived after hours fees
• UNC installed waterless hand sanitizer
• stations in the dining halls
• Cleaning supplies were made available in the
  dorms through the RAs

156
The UNC OutbreakEnvironmental Investigation and
Control Measures

• Communications
• Student emails and web postings
• Hand wash posters and signs
• UNC, State Epi and County officials
• Advisories to housekeeping staff
• Press

157
The UNC OutbreakEnvironmental Investigation and
Control Measures

• Environmental investigations / interventions
• Water line work on campus in the last two weeks?
• Chemical transportation in the last week?
• Increased fomite cleaning
• Vomitus control
• Once food and locations was suspected (1-22),
  close the facility or not?

158
The UNC OutbreakEnvironmental Investigation and
Control Measures

• Sampling through two labs (SLPH and UNC SPH)
• Food (facility keeps samples for one week)
• Stool
• Vomitus
• Review of food operations and procedures
• Assessment of connection to other concurrent
  outbreaks in the region

159
The UNC OutbreakEnvironmental Investigation and
Control Measures

• Once food and location were suspected (1-22),
  close the facility or not?
• On-going outbreak? (No)
• Extensive problems discovered during operational
  review? (No)

160
The UNC Outbreak

• Investigation Analysis / Results

161
The UNC OutbreakAnalysis / Results

• Duration - Jan. 20th thru Feb. 13th
• Total Cases - Suspected and Confirmed - ?425
  Persons
• Agent was norovirus
• Statistically linked to the salad bar at one
  dining hall
• Could not link to a specific food item

162
The UNC OutbreakAnalysis / Results

• Primary outbreak was point-source
• Many secondary cases - person-to-person and
  environmental exposure

163
The UNC Outbreak

SOURCE Drew Voetsch, UNC-CH
164
The UNC Outbreak

165
Stay Tuned for The Next Two Sessions. . .

• In July we will
• Discuss risk communication methods and strategies
  to use during outbreak investigations
• In August we will
• Develop a study design to test the Texas case
  study leading hypothesis
• Determine what evidence we need to act on the
  leading hypothesis

166
Next Session July 7th100 p.m. 300 p.m.

• Topic Risk Communication

167
Access Series Files Online http//www.vdh.virginia
.gov/EPR/Training.asp

• Session slides
• Session activities (when applicable)
• Session evaluation forms
• Speaker biographies

168
Site Sign-in Sheet

• Please submit your site sign-in sheet and
• session evaluation forms to
• Suzi Silverstein
• Director, Education and Training
• Emergency Preparedness Response Programs
• FAX (804) 225 - 3888

169
References and Resources

• FOCUS Workgroup. An Overview of Outbreak
  Investigations. FOCUS on Field Epidemiology
  (1)1. http//www.sph.unc.edu/nccphp/focus/issueli
  st.htm
• FOCUS Workgroup. Anatomy and Physiology of an
  Outbreak Investigation Team. FOCUS on Field
  Epidemiology (1)2. http//www.sph.unc.edu/nccphp/
  focus/issuelist.htm
• Hall, J.A., et al. Epidemiologic profiling
  evaluating foodborne outbreaks for which no
  pathogen was isolated by routine laboratory
  testing United States, 1982-9. Epidemiol Infect.
  2001127381-7

170
References and Resources

• Nelson, A. Embarking on an Outbreak
  Investigation. FOCUS on Field Epidemiology (1)3.
  http//www.sph.unc.edu/nccphp/focus/issuelist.htm
  
• The North Carolina Center for Public Health
  Preparedness. Outbreak Investigation Training
  website http//www.sph.unc.edu/nccphp/training/al
  l_trainings/at_outbreak.htm
• Torok, M. Case Finding and Line Listing A Guide
  for Investigators FOCUS on Field Epidemiology
  (1)4. http//www.sph.unc.edu/nccphp/focus/issueli
  st.htm