Case Study - EcoliO157H7 - Student Version

8/13/2019 Case Study - EcoliO157H7 - Student Version

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Foodborne Illness Outbreak Investigation

Case Study:Escherichia coliO157:H7

Seven physicians from bordering counties in the states of Washington and Oregon report to

their respective State Departments of Health a total of 20 individuals with severe

gastroenteritis and stool samples positive forE. coliO15!H" #he Departments of Healthfrom both states notify the $nited States %enters for Disease %ontrol and &revention '%D%("

#he %D% launches an investigation into the cluster of illnesses"

)s an epidemiologist with the %D%* it is your +ob to determine how widespread the outbrea,

has become* the source of infection* and means to halt the outbrea," #his involves

interviewing food borne illness victims* determining common e-posures* determining what

potential vehicles 'food* individuals* environmental samples* other( should be tested*interpreting laboratory results* helping to determine necessary actions to stop the outbrea,*

and helping to determine actions necessary to prevent future outbrea,s"

.ou interview the patients to determine a possible common source of infection" /rom theseinterviews* you are able to identify one commonality! all patients had visited ainy %ounty

/arm during elementary school field trips within 1 to 5 days prior to the onset of symptoms"Were their illnesses the result of consumption of one type of contaminated food or beverage*

several different contaminated foods or beverages* environmental e-posure* andor e-posure

to an infected individual Or is the farm a purely coincidental commonality and not the pointof infection

3leven patients are showing signs of recovery4 however* individuals are in reportedly in

poor medical condition and another has since died due to ,idney failure" )dditional cases ofsevere gastroenteritis have been reported in the region" 6ore people may become sic, if you

cannot identify the source 7uic,ly and recommend actions necessary to stop the outbrea,"#he public is counting on you to solve this case"

1" )side from tal,ing with farm patrons who contractedE. coliO15!H infection* who elseshould you interview to help determine what could have been the source of the illness

versus what did notcause illness

2" .ou have been provided with names of interviewees" 8ased on the information youalready have '#able 1(* prepare a list of interview 7uestions to gather more of the same

type of information from the new interviewees"

9" $sing the sets of 7uestions you developed* conduct interviews with the latest cases"

%ompile interview responses in #able 1"

:" ;raphs are helpful to 7uic,ly visuali


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b" On the same graph as plotted for part a* plot the number of patients who

developed symptoms for the dates they visited the farm"

c" #able 2 completed with data on the foods consumed by all individuals andwhether the foods were positively or negatively associated with illness"

5" ) review of farm employee health and absentee records and interviews with selectindividuals were conducted" %ould the ill farm employee listed in #able 1 have been the

original source of contamination in this outbrea, Why or why not

=" One of the individuals whose stool sample tested positive forE. coliO15!H is a food

handler in a restaurant" What additional measures should be ta,en to protect the public

" >ews of the outbrea, and the association to the farm has hit news sources includingnewspapers* radio* television* and the internet" )s a result* numerous individuals other

than those sought during the interviews have contacted their doctors* public health

professionals* andor attorneys with concerns they may also be victims in this foodborne

illness outbrea," eview the symptoms and circumstances of the cases presented in #able9* and determine which individuals may be additional victims of foodborne illness due to

this particular outbrea, versus which individuals are not li,ely to be cases associated withthis outbrea," &rovide an e-planation for your assessment on each individual"

" /rom the data compiled in #able 2* calculate the odds ratio to determine whatfoodsevents are positively associated with illness

?" What do you want to have tested forE. coliO15!H contamination

10" ;ive a reason why would you not necessarily want to have all foods tested"

11" @n any outbrea,* when there are multiple foods associated with illness* what could be thereasons for several foods being implicated

12" Aaboratory data for various foods consumed at ainy %ounty /arm and stool samplesfrom affected individuals are presented in /igure 1" Do the laboratory results support

your hypothesis on which food's( were associated with illness 3-plain your response"

19" #he $nited States Department of )griculture '$SD)( 3conomic esearch Service '3S(has an interactive website to calculate the cost of foodborne illness outbrea,s attributed to

shigaBto-in producingE. coliO15!H. 3nter the calculator at

http!www"ers"usda"govData/oodborne@llness" @n the cost component feature 'leftcolumn of the table(* clic, on Cchange number of cases" 3nter the number of ,nown

cases from this case according to how they meet the descriptions of severity of illness"

What is the estimated total cost associated with this outbrea, using the 3S assumptions

1:" @f it is concluded that a product grown and processed 'elsewhere* by two different

organi


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an opinion statement on who should be held financially accountable 'grower* processor*

retail 'ainy %ounty /arm(* other( for e-penses associated with the outbrea, including!

a" @ndividualsE medical e-penses* lost wagesb" %osts associated with determining source of outbrea, 'epidemiologist wages* lab

tests* etc"(

c" 3-penses associated with recall and destruction of food

15" )fter this outbrea,* various groups with sta,e in this issue met to discuss appropriate

actions for consumer protection with this type of product" #wo alternatives werediscussed" Which of these do you favor State the reason's( for your opinion"

a" Aabel product with a warning that it might contain microorganisms that can cause

illness"b" e7uire treatment to ,ill pathogenic bacteria prior to distribution to the consumer"

1=" @f a vaccine could be developed to minimi


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Table 1. Data fro Intervie!s !it" Individuals

Individual #ender$ge

%yrs&Sy'tos

Date

Sy'to

Onset

Date visited

Far

('loyee)

*atron) Close

Conta+t

Consued *arti+i'ated

S'e+ial

Healt"

Con+erns

Curren

Healt" St

1 /emale 8D* H$S* )*

F/Oct 2 Oct 1 &atron H* G* @ O >F Deceas

2 /emale 8D* H$S Oct 2 Oct 1 &atron H* G* @ O >F &oor*

Hospitali

9 6ale 8D* H$S Oct 2 Oct 1 &atron H* G* @ O* & >F &oor*

Hospitali

: /emale 8D Oct 9 Oct 1 &atron H* G* @ O* & >F ecover

5 6ale 8D Oct 9 Oct 1 &atron H* G* @ & >F ecover

= 6ale 8D Oct 2 Oct 1 &atron G* @ & >F ecover

6ale 8D Oct 2 Oct 1 &atron G* A* @ & >F ecoveri

Hospitali

6ale 95 8D Oct : Oct 1 &atron H* G* W* A O* & >F ecover

? /emale = 8D Oct 9 Oct 2 &atron S* G* @ & >F ecover

10 /emale 8D* H$S Oct 9 Oct 2 &atron G* @ >) >F &oor*

Hospitali

11 6ale 8D Oct : Oct 2 &atron H* G* @ O* & >F ecover

12 /emale 2? 8D Oct : Oct 2 &atron S* G >) >F ecover

19 6ale 8D Oct 5 Oct : &atron H* G* @ >) >F &oor

1: 6ale 8D Oct 5 Oct : &atron H* G O* & >F &oor

15 6ale 8D* / Oct 5 Oct : &atron H* G* A & >F ecover

1= /emale 8D* H$S Oct Oct = &atron G* A* @ >) >F &oor*

hospitali

1 /emale 8D Oct Oct = &atron H* G* W O >F &oor

1 /emale 8D* I Oct Oct = &atron H*G O* & >F ecover

1? /emale 25 8D Oct 10 Oct = 3mployee S* G >) >F ecover

20 6ale 29 8D Oct 11 Oct = 3mployee H* A* @ & >F &oor

21J

22J

29J2:J

25J

2=J

2J

JData gathered by students through mock interviewsSy'tos ,ey! 8D* bloody diarrhea4 I* vomiting4 /* fever4 H$S* hemolytic uremic syndrome4 F/* ,idney failure4 )* anemia)ll sic, individuals visited their physicians"Food ,ey! S* salad4 H* hamburger4 G* freshBpressed apple +uice4 A* fresh lemonade4 W* water4 @* ice cream*(vent ,ey! &* petting


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Table -. $+tivityConsu'tion at Far and $sso+iation !it" Illness

Food or

$+tivity

/

Consued

or

'arti+i'ate

d and Si+k

/

Consued

or

'arti+i'ate

d 0ot Si+k

/ 0ot

Consued

or

'arti+i'ate

d and Si+k

/ 0ot

Consued

or

'arti+i'ate

d and 0ot

Si+k

Odds atio

2n'asteuri3ed$''le 4ui+e

ottled 6ater

eonade

Haburger

Salad

I+e Crea

*etting 8oo

Or+"ard

*i+king

Odds atio K L'M %onsumed and Sic,(

'M>ot %onsumed and Sic,(NL'M %onsumed >ot Sic,( 'M>ot %onsumed and >ot Sic,(N

Table 9. 0e! Cases elated to Outbreak;

Individual Sy'tosSy'to

Onset

Sy'to

Duration

Date


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Figure 1. aboratory Data fro Food *rodu+ts) (nvironental S!abs) and *atient Stool

S'e+ien fro ainy County Far$sso+iated Illness Outbreak

&ulsed field gel electrophoresis results"8acterial isolates from growth media are treated with

en


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$''endi= $

$+tor es'onses for Intervie!ees / -1 -7 to Co'lete Table 1.

0ote: Only 'rovide ans!ers if >uestions asked. Do not offer unsoli+ited inforation.

$+tor 1!

6ale* age 99 years">ot sic,* health currently good" >o ,nown health problems"

&atron of farm on October 9"%onsumed salad* hamburger* lemonade* and ice cream" &articipated in orchard pic,ing and petting

ot sic,* health currently good" >o ,nown health problems"

&atron of farm on October ="%onsumed salad* hamburger* and lemonade" &articipated in orchard pic,ing and petting ot sic,* health currently good" >o ,nown health problems"

&atron of farm on October ="%onsumed salad* hamburger* and water" &articipated in orchard pic,ing and petting ot sic,* health currently good" >o ,nown health problems"

3mployee of farm" Wor,ed on October 5"

%onsumed hamburger and ice cream" &articipated in petting ot sic,* health currently good" >o ,nown health problems"3mployee of farm" Wor,ed October :"

%onsumed hamburger* +uice* water* and lemonade" Did not partipate in orchard pic,ing or petting

ot sic,* health currently good" >o ,nown health problems"&atron of farm on October :"

%onsumed salad* hamburger* and water" &articpated in orchard pic,ing"

$+tor 7:

6ale* age 95 years"

>ot sic,* health currently good" >o ,nown health problems"&atron of farm on October 9"

%onsumed salad* lemonade* and ice cream" &articipated in orchard pic,ing and petting

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Case Study - EcoliO157H7 - Student Version