diseases in nature conference john herbold dvm, mph, phd, dacvpm, face center for biosecurity &...

Diseases in Nature ConferenceDiseases in Nature Conference

John Herbold DVM, MPH, PhD, DACVPM, FACE Center for Biosecurity & Public Health Preparedness

University of Texas School of Public Health

Austin, Texas, June 11th 2007

Disease Outbreak Investigations


““...So far this appears to be an isolated case”...So far this appears to be an isolated case”CDC Press Release on Florida Anthrax CaseCDC Press Release on Florida Anthrax Case

A ‘Cutting Edge’ Review ofA ‘Cutting Edge’ Review ofDisease Outbreak Investigation Disease Outbreak Investigation

StrategiesStrategies

OUTLINE OF THE INVESTIGATION OF AN EPIDEMIC

Mausner & Bahn, Epidemiology An Introductory Text, 1985

...an exciting exercise in medical detection...an exciting exercise in medical detection

...painstaking accumulation of data...painstaking accumulation of datain the fieldin the field

...careful analysis of data...careful analysis of data

...flashes of insight...flashes of insight

...systematic outline...systematic outline

Mausner & Bahn Outline

Preliminary Analysis

•Verify the Diagnosis•Verify the Existence of an epidemic

•Describe the Epidemic by PPT•Formulate and Test Hypotheses


Possible Further Investigation and Analysis

•Search for Additional Cases•Analyze the Data•Make a Decision [Hypotheses Considered]•Intervention and Follow-up


Report of the Investigation

•include discussion of factors

•evaluation of measures used for control

•recommendations for prevention

‘strategy’ to investigate the etiology of diseaseI. Confirm the existence of a health problemI. Confirm the existence of a health problem

A. Define cases in terms of person, place, and timeA. Define cases in terms of person, place, and timeB. Describe what you see..............B. Describe what you see..............C. Discuss explanations for associations that you seeC. Discuss explanations for associations that you see

II. Discuss possible causes, etiology, of the problemII. Discuss possible causes, etiology, of the problemA. Assess information, literature, consult specialistsA. Assess information, literature, consult specialistsB. Generate possible/potential hypotheses....B. Generate possible/potential hypotheses....C. Display ('examine') the evidence (information)C. Display ('examine') the evidence (information)

III. Test specific hypothesis (ses)III. Test specific hypothesis (ses)IV. Action (intervention, prevention, clinical trial)IV. Action (intervention, prevention, clinical trial)V. Experimental (laboratory, animal models, etc.)V. Experimental (laboratory, animal models, etc.)VI. Review I through V and develop unifying theoryVI. Review I through V and develop unifying theoryVII. Publish a report ... present in a public forumVII. Publish a report ... present in a public forumVIII. VIII. Re-Re-confirm (that's why its called confirm (that's why its called re-re-search)search)

Reference: Roht et al, Reference: Roht et al,

“Ten” Steps For Investigating An Epidemic

Prepare for field work (re – search the literature; talk to experts) Establish the existence of an outbreak (endemic, epidemic,

cluster, outbreak) Verify the diagnosis (clinical, laboratory, epidemiologic) Define and identify cases Establish a case definition Identify and count cases Perform descriptive epidemiology (person, place, time) Develop hypotheses Evaluate Hypotheses Reconsider/refine hypotheses and execute additional studies Implement control and prevention measures Communicate findings

Reference: CDC Satellite Broadcast Course, 1993Reference: CDC Satellite Broadcast Course, 1993

Time to get to work !!!

• Late Friday afternoon... Of course• Phone Call to LHD from Local Physician• Looks like hepatitis...

– 1 adult patient who also tells Doc...• 2 colleagues at work (law office downtown)• Diagnosed this week also...

Time to get to work !!!

What first steps should be taken???What first steps should be taken???

Read up on hepatitisExact dates of onsetInterview 3 cases (travel hx)Line listing of patients (demographics)Interview co-workers (jobs, restaurants, social)What’s community experience with hepatitisExtent of outbreak outside law officeNumber of cases over past yearAnything else??

What first steps should be taken???What first steps should be taken???

Disease Outbreak Investigations Video One

Know .. Know .. 3 cases of hepatitis A within the week3 cases of hepatitis A within the weekHx of only 12 cases last yearHx of only 12 cases last yearAnytown USAAnytown USA

What would you use for a case definition ?What would you use for a case definition ?

What would you do next ?What would you do next ?


What would you use for a case definition What would you use for a case definition ??Clinical & Laboratory parametersClinical & Laboratory parameters

• (Person)(Person)3 cases date of onset plus/minus 3 days3 cases date of onset plus/minus 3 days

• (Time)(Time)People in Law OfficePeople in Law Office

• (Place)(Place)


What would you do next ?What would you do next ?

Expand search for casesExpand search for cases• (law firm and family members)(law firm and family members)

Look @ community experienceLook @ community experience• (labs, hospital, cases past month)(labs, hospital, cases past month)

Other suggestions.....Other suggestions.....This looks like a ‘lot of work’ !This looks like a ‘lot of work’ !

Disease Outbreak Investigations Video Two

Know .. Know .. 32 cases of hepatitis A within the week32 cases of hepatitis A within the weekNot confined to law officeNot confined to law officeLive all over the countyLive all over the county

What type of outbreak is this?What type of outbreak is this?•point sourcepoint source•continuing common sourcecontinuing common source•person to personperson to person

What do you think caused it?What do you think caused it?

How would you check your hypothesis?How would you check your hypothesis?


What type of outbreak is this?What type of outbreak is this?

point source (time/place cluster)point source (time/place cluster)... food .... water... food .... water

continuing common source (#’s)continuing common source (#’s)... water... water

person to person (incubation period)person to person (incubation period)


What do you think caused it?What do you think caused it?

FoodFood

WaterWater

Other ?Other ?


How would you check your hypothesis?How would you check your hypothesis?

Municipal water system recordsMunicipal water system records

Food histories of patientsFood histories of patients

Other ?Other ?

Disease Outbreak Investigations Video Three

Know .. Know .. 32 cases of hepatitis A within the week32 cases of hepatitis A within the weekNot confined to law officeNot confined to law officeLive all over the countyLive all over the countyMost likely foodborneMost likely foodborne

How would you design studies to How would you design studies to evaluate various foodborne routes?evaluate various foodborne routes?

What foods would you suspect and What foods would you suspect and why?why?


How would you design studies to How would you design studies to evaluate various foodborne routes?evaluate various foodborne routes?

Cases and co-workers as Cases and co-workers as controlscontrols

Where & how often did you eat Where & how often did you eat downtowndowntown

Food preferencesFood preferences


What foods would you suspect and What foods would you suspect and why?why?

SaladsSaladsFresh fruitsFresh fruitsUncooked vegetablesUncooked vegetablesSeafood (raw)Seafood (raw)

Pizza ?Pizza ?

Disease Outbreak Investigations Video Four

Louisville KY 1988Louisville KY 1988

more than 200 cases confirmedmore than 200 cases confirmed

immune globulin given to contactsimmune globulin given to contacts

13% of cases hospitalized !13% of cases hospitalized !

little secondary spreadlittle secondary spread

no children “Adult Outbreak”no children “Adult Outbreak”

Reginald Finger MD,MPH

KY State Epidemiologist

Melodious VoiceMark Garmack UAB SPH

PRODUCED BYPRODUCED BYAlabama Department of HealthAlabama Department of Health

Principles of Epidemiology By SatellitePrinciples of Epidemiology By SatelliteMay 20May 20thth 1993 1993

HOW DID WE DO ?????

One WorldOne World

One MedicineOne Medicine

One EcologyOne Ecology

diseases in nature conference john herbold dvm, mph, phd, dacvpm, face center for biosecurity &...

Documents

hepatitisextent of outbreak

outbreak endemic

cases of hepatitis

field work

law officenumber of

epidemicmausner bahn

test hypothesesmausner

systematic outlinemausner