2004 Public Health Training and Information Network (PHTIN) Series

1
2004 Public Health Training and Information
Network (PHTIN) Series
2
Site Sign-in Sheethttp//www.sph.unc.edu/nccphp/

• First and Last Name
• Occupation
• Place of Employment
• Mailing Address
• Email Address

3
Site Sign-in Sheet http//www.sph.unc.edu/nccphp/

• Please mail or fax your sites sign-in sheet to
• Jennifer Horney
• Director of Training and Education
• NC Center for Public Health Preparedness
• CB 8165, 400 Roberson
• Chapel Hill, NC 27599
• FAX (919) 843 - 5563

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Outbreak Investigation Methods

• From Mystery to Mastery

5

6
2004 PHTIN Training Development Team

• Jennifer Horney, MPH - Director, Training and
  Education, NCCPHP
• Pia MacDonald, PhD, MPH - Director, NCCPHP
• Amy Nelson, PhD
• Penny Padgett, PhD, MPH
• Sarah Pfau, MPH
• Michelle Torok, MPH, Doctoral Candidate
• Drew Voetsch, MPH, Doctoral Candidate

7
Future PHTIN Sessions

• June 8th. . . . . . . . . . . . Study Design
• August 17th. . . . . . . . . .Interviewing
  Techniques
• September 14th. . . . . . .Designing
  Questionnaires
• October 12th. . . . . . . . . Analyzing Data
• December 14th. . . . . . . Risk Communication
• Each session will be on a Tuesday from 1000 am -
  1200 pm
• (with time for discussion)

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Session I VI Slides

• After the airing of each session, NCCPHP will
  post PHTIN Outbreak Investigation Methods series
  slides on the following two web sites
• NCCPHP Training web site
• http//www.sph.unc.edu/nccphp/training/index.html
• North Carolina Division of Public Health, Office
  of Public Health Preparedness and Response
• http//www.epi.state.nc.us/epi/phpr/

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Session I

• Recognizing an Outbreak

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Todays Presenters

• Drew Voetsch, MPH
• Research Associate and Doctoral Candidate, NCCPHP
• Penny Padgett, PhD, MPH
• Epidemiologist / Surveillance Officer, NCCPHP
• Ron Holdway
• Environmental Health Director, Orange Co. Health
  Dept.
• Sarah Pfau, MPH
• Moderator

11
Recognizing an OutbreakLearning Objectives

• At the end of this session, you will be able to
• Identify multiple types of food borne illness
  surveillance systems
• Recognize uses of surveillance data
• Identify CDCs steps of an outbreak investigation

12
Recognizing an OutbreakLearning Objectives
(contd.)

• At the end of this session, you will be able to
• Develop and use a case definition
• Apply the process of case finding in an outbreak
• Follow methods for generating a hypothesis

13
Recognizing an OutbreakSession Content

• 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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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

16

• 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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Uses of Surveillance

1. Estimate the magnitude of the problem
2. Determine the geographic distribution of illness
3. Portray the natural history of a disease
4. Detect epidemics / define a problem
5. Generate hypotheses, stimulate research
6. Evaluate control measures
7. Monitor changes in infectious agents
8. Detect changes in health practice
9. Facilitate planning

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Reportable Diseases in NC
http//www.epi.state.nc.us/epi/gcdc/pdf/10ANCAC41A
.pdf
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Estimate the Magnitude of the Problem

• Cases and reported incidence (cases / 100,000) of
  food borne diseases in North Carolina, 2002

Disease Cases Incidence
Campylobacteriosis 683 8.2
E. coli O157 infection 244 2.9
Foodborneother 281 3.4
Hepatitis A 209 2.5
Salmonellosis 1655 19.9
Shigellosis 1074 12.9
(http//www.epi.state.nc.us/epi/gcdcpdf/CD1991-200
2.pdf)
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Determine the Geographic Distribution of Illness
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Portray the Natural History of a Disease

• Incidence (cases per 100,000) of selected food
  borne diseases in North Carolina, 1991-2002

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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

26
Types of Surveillance

• Active vs. passive
• Clinician vs. laboratory

27
Outbreak Surveillance Sources

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

28
Outbreak Investigation
29
Why Investigate?

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

30
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

31
CDC Guidelines for Systematic Investigations
(contd.)

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

32
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
34
Case Study

• The case study that will be used in todays
  session and the June 8th session is based on an
  outbreak that occurred in Austin, Texas in 1998.

35
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

38
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
41
Case ReportWhat
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Case ReportWhen/How
43
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

44
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?

45
Disease SurveillanceWhat next?

• File the report and stop?
• Investigate further?

46
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)

49
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

50
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 time, place, and person

54
Case Definition

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

55
Case Finding Using the Case Definition

• Initial Case Definition University student with
  diarrhea/vomiting in the previous 24 hours
• Look for more cases (student health center,
  hospitals, clinicians, dorm rooms) to determine
  the extent of the potential outbreak

56
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)

57
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

58
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

59
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!

60
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

61
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
63
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

65
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

66
Verify the Diagnosis Potential Enteric Agents
Viruses Bacteria Parasites Toxins
Norwalk Campylobacter Cyrptospor-idium parvum Clostridium botulinum
Norwalk-like viruses (caliciviruses) E. coli Cyclospora Staph. aureus
Rotavirus Salmonella spp. Giardia Mushroom toxins
Hepatitis A Shigella Entamoeba histolytica Fish/Shellfish toxins
67
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

68
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

69
Epidemiological Profiling
Syndrome Incubation (hours) Duration (hours) Vomiting Fever V / F
Vomiting-toxin 1.5-9.5 6.3-24 50-100 0-28 0-4.3
Diarrhea toxin 10-13 12-24 3.6-20 2.3-10 0.4-1.3
E. coli 48-120 104-185 3.1-37 13-25.3 0.3-1.1
Norovirus 34.5-38.5 33-47 54-70.2 37-63 0.7-1.7
Salmonella-like 18.0-88.5 63-144 8.9-51 31-81 0.2-1.0
Epidemiol Infect. 2001127381-7
70
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

72
Epidemiological Profiling
Duration Vomiting Vomiting / Fever
Case Study 39 hours (median) 90 of cases 1.34
Kaplan Criteria for Norovirus 16 20 hours gt 50 of cases gt 1.0
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Noroviruses

• Todays Guest Expert
• Penny Padgett, PhD, MPH

74
NOROVIRUSES

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

75
Physical Properties

• Relatively resistant to environmental challenge
  they are able to withstand freezing and
  temperatures as high as 60 degrees Celsius
  (steamed shellfish)
• May be present in up to 10 ppm chlorine

76
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

78
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

79
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

80
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

81
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

82
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.

83
Specimen Collection

• Environmental
• Food and water samples can be collected and
  tested. Water samples should be filtered to
  increase the concentration of virus present

84
Detection of Virus

• Reverse Transcription-Polymerase Chain Reaction
  (RT-PCR) is considered to be a highly sensitive
  and accurate method for viral detection
• Direct and Immune electron microscopy
• Detection of a fourfold increase in specific
  antibodies in acute and convalescent serum
  samples
• An Enzyme Linked Immunosorbent Assay (ELISA) for
  detection in stools is under development

85
Prevention

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

86
Cruise Ships
87
Cruise Ships

• Cruise ships represent a closed population which
  can be studied as a cohort
• Highly infectious agents can spread very quickly
  through the population
• Difficult to clean and contain infection during
  the cruise

88
Vessel Sanitation Program

• Unannounced, twice yearly inspections
• Inspection takes place in U.S. ports
• Ships are required to maintain a standardized
  illness report for each cruise

89
Microbiologic Investigation Specimen Information

• Each stool specimen should be submitted with
• Patients name or identification number
• Dates
• Date of collection of specimen
• Date of onset of symptoms
• Signs and symptoms
• may suggest a particular agent and lead the lab
  to perform specific testing

90
Additional Specimen Information

• If submitting a stool specimen for multiple
  tests, divide, label, and preserve each sample
  accordingly
• Indicate on the requisition slip if testing is
  requested for specific, suspected pathogens

91
Additional Specimen Information

• If you have questions prior to submitting a
  stool specimen, contact the NC State Laboratory
  of Public Health at
• [phone]
• Web site http//slph.state.nc.us/

92
Specimen Collection Recommendations

• More information on recommendations for
  collection of stool specimens for laboratory
  examination may be found in
• Morbidity and Mortality Weekly Report
  Recommendations and Reports 1990 30 (No. RR-14)

93
Case Study

• Back to the lecture on Verifying the Diagnosis. .
  .

94
Verify the Diagnosis Culture Results

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

95
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

96
Microbiology DiagnosisInterpretation of Results

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

97
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

98
Case Study

• Hypothesis Generation

99
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

100
Hypothesis GenerationLine Listing

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

101
Hypothesis GenerationEpidemic Curve
Most dates of illness onset were March 9-12
102
Hypothesis GenerationMeet with University
Officials

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

103
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

104
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

105
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

106
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

107
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

108
Hypothesis GenerationInformation Collected

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

109
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

110
Hypothesis GenerationCase Interviews

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

111
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

112
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

113
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

114
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

115
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

116
Hypothesis Generation
117
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)

118
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

119
Hypothesis Generation1. Pathogen
Epi Curve suggests a point source outbreak and
short exposure period More consistent with a
virus than parasite
120
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

121
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

122
Hypothesis Generation 3. Source

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

123
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)

124
Hypothesis Generation

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

125
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

126
What Next?

• Next Steps
• Environmental investigation
• Conduct a controlled study

127
Environmental Investigation

• Todays Guest Expert
• Ron Holdway,
• Environmental Health Director, Orange Co. Health
  Department

128
ORANGE COUNTY HEALTH DEPARTMENTDR. ROSEMARY
SUMMERS, DIRECTOR

• ENVIRONMENTAL HEALTH DIVISION

129
ORANGE COUNTY HEALTH DEPARTMENT
THE NOROVIRUS OUTBREAK AT THE UNIVERSITY OF NORTH
CAROLINA January 2004

• Presented April 13th, 2004

130
The UNC Outbreak

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

131
The UNC Outbreak

• Background

132
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

133
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

134
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

135
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

136
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?

137
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

138
The UNC Outbreak

• Questions and Issues

139
The UNC OutbreakQuestions and Issues

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

140
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

141
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

142
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

143
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

144
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

145
The UNC Outbreak

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

146
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

147
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

148
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?

149
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

150
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)

151
The UNC Outbreak

• Investigation Analysis / Results

152
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

153
The UNC OutbreakAnalysis / Results

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

154
The UNC Outbreak

SOURCE Drew Voetsch, UNC-CH
155
The UNC Outbreak

156
Case Study

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

157
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

158
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

159
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

160
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

161
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

162
Environmental Investigation Sampling

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

163
Environmental InvestigationEvidence-Based
Decision

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

164
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?

165
Todays Conclusions

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

166
Stay Tuned for the Next Session. . .

• Next time we will
• Develop a study design to test the leading
  hypothesis
• Determine what evidence we need to act on the
  hypothesis

167
Next Session June 8th1000 a.m. - Noon

• Topic Study Design

168
Session I Slides

• Following this program, please visit one of the
  web sites below to access and download a copy of
  todays slides
• NCCPHP Training web site
• http//www.sph.unc.edu/nccphp/training/index.html
• North Carolina Division of Public Health, Office
  of Public Health Preparedness and Response
• http//www.epi.state.nc.us/epi/phpr/

169
Site Sign-in Sheet http//www.sph.unc.edu/nccphp/

• Please mail or fax your sites sign-in sheet to
• Jennifer Horney
• Director of Training and Education
• NC Center for Public Health Preparedness
• CB 8165, 400 Roberson
• Chapel Hill, NC 27599
• FAX (919) 843 - 5563