Investigating FooInvestigating FooOutbreaks: The COutbreaks: The COutbreaks: The COutbreaks: The C

Ian WilliamChief, Outbreak Respons

Division of Foodborne, bacCenters for Disease C

The findings and conclusions in this presentation are thoviews of the Centers for Dise

odborne Disease odborne Disease CDC PerspectiveCDC PerspectiveCDC PerspectiveCDC Perspective

ms, PhD, MSse and Prevention Branchcterial and Mycotic DiseasesControl and Prevention

ose of the author and do not necessarily represent the ase Control and Prevention

The Spectrum of FoodbThe Spectrum of Foodb

• Old focal scenario •• Large number of cases in

one jurisdictionDetected by affected• Detected by affected group

• Local investigation• Local food handling error• Local solution

These changes make coordinatioThese changes make coordinatioagencies, and countries even m

borne Disease Outbreaksborne Disease Outbreaks

New dispersed scenario• Small numbers of cases in

many jurisdictionsDetected b lab based• Detected by lab-based subtype surveillance

• Multistate/Country yinvestigation

• Industrial contamination eventevent

• Broad implications

n among multiple states andn among multiple states and more important than before

Public Health InfrastructPublic Health Infrastruct• The county or city health d

• The front line of public heap• The State health departme

• Epidemiologists• Laboratorians• Sanitarians

Th f d l i• The federal agencies:• Risk identification agency:• Risk management/regulato• Risk management/regulato

• "Tiered response" to emer• CDC provides back-up to SCDC provides back up to S

laboratory support, coordi

ture in the United Statesture in the United Statesdepartmentalthent

CDC (non-regulatory)ory agencies: FDA USDA EPAory agencies: FDA, USDA, EPArgencies States: epidemiologistsStates: epidemiologists, nation

FederaFedera

• CDC:– Disease surveillance

Outbreak detection and

•

– Outbreak detection and investigation

– Education and training of bli h l h ffpublic health staff

Problem identificationProblem identification

Source implication

l Roles l Roles

FDA & FSIS:– Food safety policies

I ti d f t– Inspection and enforcement– Product recall and traceback– Investigation of farm and– Investigation of farm and

production facilities

Risk assessment andRisk assessment and management

Source assessment

Foodborne Disease OuFoodborne Disease Ou• Goals of investigations

–– Immediate control of outbrImmediate control of outbr–– Provide opportunities to idProvide opportunities to id

systemssystems

• Outbreak epidemiology c• Outbreak epidemiology c– Globalization, centralizatio

Number of possible outbre– Number of possible outbresubstantially

• Effective investigations kEffective investigations kfoodborne disease– Identify food vehicles and y

utbreak Investigationsutbreak Investigations

reak and prevention of illnessesreak and prevention of illnessesdentify gaps in food safety dentify gaps in food safety

changingchangingon, industrialization eaks detected has growneaks detected has grown

key to reducing burden ofkey to reducing burden of

factors which lead to outbreaks

Cycle of FoodbornCycle of Foodbornand Pre

Survei

AppliedAppliedResearch

PreventMeasu

ne Disease Controlne Disease Control evention

illance

EpidemiologicEpidemiologicInvestigation

tionres

Cycle of Foodborne Cycle of Foodborne P ti StP ti StPrevention: Stages Prevention: Stages

Survei

Detecting a cluster (inc

Applied

Detecting a cluster (incabove baseline

Research

PreveMMeas

Outbreak Control & Outbreak Control & f I ti tif I ti tiof an Investigationof an Investigation

llance

crease # of infections

Epidemiologic

crease # of infections for time period)

Investigation

ntionsures

National SurveillaNational SurveillaF dbF dbFoodborneFoodborne

• Reports to CDC of suspReports to CDC of suspand local health departm

• Laboratory-based surve– Serotype resultsyp

– PulseNet

ance for Bacterial ance for Bacterial I f iI f ie Infectionse Infections

pected outbreaks by statepected outbreaks by state ments

eillance of clinical isolates

What is PulseNWhat is PulseNWhat is PulseNWhat is PulseN

National net ork of >75 p b• National network of >75 publaboratories

• Perform molecular typing of• Perform molecular typing ofbacteria – Current method is pulsed-fieCurrent method is pulsed fie– Create DNA “fingerprints”

• Share DNA “fingerprints” elShare DNA fingerprints el• DNA “fingerprints” are kept

– available on-demand to partavailable on demand to part

Net USA?Net USA?Net USA?Net USA?

blic health and reg latorblic health and regulatory

f foodborne disease causingf foodborne disease-causing

eld gel electrophoresis (PFGE)eld gel electrophoresis (PFGE)

ectronicallyectronicallyin dynamic database at CDC

ticipantsticipants

PulseNet Data Analysis:PulseNet Data Analysis:yy

Cluster of indistinguishable pattCluster of indistinguishable patt

Searching for Clusters Searching for Clustersgg

•State health depts submit patterns electronicallypatterns electronically

•CDC searches for similar patterns in past 2 4 monthspatterns in past 2-4 months

•CDC compares patterns visuallyvisually

•When cluster identified, PulseNet contacts

terns

PulseNet contacts epidemiologists

terns

Cycle of Foodborne Cycle of Foodborne PPPrevePreve

Survei

AppliedR hResearch

PrevenMMeasu

Outbreak Control & Outbreak Control & titientionention

llance

EpidemiologicInvestigation

ntionures

CDC’s OutbreCDC’s Outbre• Supports a national network of

public health officials who invet b d th t iwaterborne, and other enteric

• Collaboration between CDC anU S State and local health departmen– U.S. State and local health departmen

– U.S. Department of Agriculture (USDA– U.S. Food and Drug Administration (F

• Works in close partnership wit– The national molecular subtyping net

• Helps ensure – Rapid, coordinated detection & respo– Promotes comprehensive outbreak sPromotes comprehensive outbreak s

eakNet TeameakNet Teamf epidemiologists and other estigate outbreaks of foodborne, ill i th U it d St tillnesses in the United States

ndntsnts A) FDA)

th PulseNet twork for foodborne disease surveillance

onse to multi-state enteric disease outbreakssurveillancesurveillance

Cycle of Foodborne DiseaCycle of Foodborne DiseayyStages of an OutbStages of an Outb

SurveillanceDetecting a cluster in the first place

EpidI

AppliedResearch InveResearch

PreventionMeasures

ase Control & Prevention: ase Control & Prevention: reak Investigationreak Investigation

emiologicti ti

- Generating hypotheses

- Testing hypothesesestigation Testing hypotheses

- Reconstructing how and wherecontamination is likely to have occurredoccurred

Hypothesis Gener• Strategies include:

I t i ith t t– Interviews with structurefood items: “trolling, trawI t i d d i t– Intensive open-ended intdays before illness bega• In depth interview with pe• In-depth interview with pe

refrigerator, pantry

– Some combination of theSome combination of the– All should be done the sa

A food product is not the• A food product is not the

rating Interviews

d ti i ithd questionnaire with many wling, or shotgun”t i b t f d t i 7terviews about food eaten in 7

aneople in their homes includingeople in their homes, including

e twoe twoame way

e source of all outbreaks!e source of all outbreaks!

HypothesisHypothesis--GeneraGeneraHypothesisHypothesis GeneraGenera

• Data on product distrib• Data on product distribbe critical in developm

Evaluate potential sour– Evaluate potential sour• Ways to obtain this inf

– State Departments of A– Regulatory agencies

• Involvement before a procan pose unique problem

ating Tracebacksating Tracebacksating Tracebacksating Tracebacks

bution production canbution production can ment of hypothesisrcesrcesformation

Agriculture

oduct has been implicated m for some agencies

Testing HyTesting Hy• Systematically compare exp

remained well– Two structures of investigatio

• Illness in a defined group (cohoabout exposures and subseque

• Illness in cases and controls: inhealthy persons (controls) abou

– Measure statistical associatio• Direction of association (Sh• Probability of chance alone (Sh• Strength of association (Nog (• Dose-response relationship (Su

• Plausibility of associationR t• Repeat process as necessa

ypothesesypothesesposures of ill and those who

onort) after an event: interview whole group ent illnessnterview the ill people and comparable ut preceding exposureson of illness with each exposurehould be positive)hould be < 5%)o fixed rule))upports if present)

ary

Cycle of Foodborne DiseaCycle of Foodborne DiseaSt f O tbSt f O tbStages of an OutbStages of an Outb

Survei

AppliedResearch

PrevePreveMeas

ase Control & Prevention: ase Control & Prevention: k I ti tik I ti tireak Investigationreak Investigation

illance

EpidemiologicEpidemiologicInvestigation

entionentionsures

PreventionPrevention

T b k ITraceback In

Epidemiologic Investigations

LabInves

Measures Measures

ti tinvestigations

Environmental Assessments

boratory ystigations

http://www cdc gov/fhttp://www.cdc.gov/f

The findings and conclusions in this presentation are thoseviews of the Centers for Disease

foodborneoutbreaks/foodborneoutbreaks/

of the author and do not necessarily represent the e Control and Prevention