Chapter 11 Discussion Learning Objectives By the end of this chapter, the reader will be able to: State three measures for preventing foodborne illnesses Discuss 10 microbiological agents that are implicated in foodborne illness Explain the significance of foodborne illness for the world’s population List five categories of contaminants in the food supply Describe one major regulation for protecting the safety of food from carcinogens Foodborne Diseases/Infections “illnesses acquired by consumption of contaminated food; they are frequently and inaccurately referred to as food poisoning” An outbreak indicates “the occurrence of a similar illness among two or more people which an investigation linked to consumption of a common meal or food items, except for botulism (one case is an outbreak)” Burden of Illness Pyramid Risk Factors for Foodborne Illness – USA 63% Inadequate cooling and cold holding temperatures 29% Preparing food ahead of planned event 27% Inadequate hot holding temperatures 26% Poor personal hygiene/infected persons 25% Inadequate reheating 9% Inadequate cleaning of equipment 7% Use of leftovers 6% Cross-contamination 5% Inadequate cooking or heating process … List goes on… Risk Factors for Foodborne Illness So what are some of the prevention measures we can take? Clean, separate, cook, & chill Hand hygiene Irradiation of food (common for meats) Risk Factors for Foodborne Illness Investigating Foodborne Outbreaks Detecting a possible outbreak Defining and finding cases Generating hypotheses about likely sources Testing the hypotheses Finding the point of contamination Controlling an outbreak Deciding an outbreak is over Investigating Foodborne Outbreaks Detecting a possible outbreak Defining and finding cases Generating hypotheses about likely sources Testing the hypotheses Finding the point of contamination Controlling an outbreak Deciding an outbreak is over First step of process Generally through public health surveillance (usually passive) Nationally Notifiable Conditions Establish a normal baseline incidence of a given disease Detect an increase in the incidence, or a “cluster” If the cluster has something in common, then it is considered an outbreak Investigating Foodborne Outbreaks Detecting a possible outbreak Defining and finding cases Generating hypotheses about likely sources Testing the hypotheses Finding the point of contamination Controlling an outbreak Deciding an outbreak is over Usually the first cases identified are only a small part of the total outbreak Develop a “case definition”, including: Pathogen & symptoms Time range & geographic area Other criteria (common source or DNA/PFGE fingerprint) May distinguish probable vs. confirmed Using the case definition, active surveillance for additional cases Surveying individuals Looking through health records/laboratory reports Reaching out to other health officials Investigating Foodborne Outbreaks Detecting a poss.

1. Chapter 11 Discussion
Learning Objectives
By the end of this chapter, the reader will be able to:
State three measures for preventing foodborne illnesses
Discuss 10 microbiological agents that are implicated in
foodborne illness
Explain the significance of foodborne illness for the world’s
population
List five categories of contaminants in the food supply
Describe one major regulation for protecting the safety of food
from carcinogens
Foodborne Diseases/Infections
“illnesses acquired by consumption of contaminated food; they
are frequently and inaccurately referred to as food poisoning”
An outbreak indicates “the occurrence of a similar illness
among two or more people which an investigation linked to
consumption of a common meal or food items, except for
botulism (one case is an outbreak)”
Burden of Illness Pyramid

2. Risk Factors for Foodborne Illness – USA
63% Inadequate cooling and cold holding temperatures
29% Preparing food ahead of planned event
27% Inadequate hot holding temperatures
26% Poor personal hygiene/infected persons
25% Inadequate reheating
9% Inadequate cleaning of equipment
7% Use of leftovers
6% Cross-contamination
5% Inadequate cooking or heating process
… List goes on…
Risk Factors for Foodborne Illness
So what are some of the prevention measures we can take?
Clean, separate, cook, & chill
Hand hygiene
Irradiation of food (common for meats)
Risk Factors for Foodborne Illness
Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over

3. Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over
First step of process
Generally through public health surveillance (usually passive)
Nationally Notifiable Conditions
Establish a normal baseline incidence of a given disease
Detect an increase in the incidence, or a “cluster”
If the cluster has something in common, then it is considered an
outbreak
Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over
Usually the first cases identified are only a small part of the
total outbreak
Develop a “case definition”, including:
Pathogen & symptoms
Time range & geographic area
Other criteria (common source or DNA/PFGE fingerprint)

4. May distinguish probable vs. confirmed
Using the case definition, active surveillance for additional
cases
Surveying individuals
Looking through health records/laboratory reports
Reaching out to other health officials
Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over
Developing possible sources of illness, modes of transmission,
and even a specific source
Iterative process, where hypotheses are continually refined or
refuted
When lots of potential exposures, conduct “hypothesis-
generating interviews” to determine common exposures (e.g.
food items consumed)
Challenging due to memory and amount of items consumed
Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over

5. Once hypotheses are generated, need to test them to see if
correct source was identified
Case-control studies are the most common type of tests
Controls may be matched on geography and time
Determine if eating a particular item was statistically more
common for cases
What test is used to help determine?
Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over
Based upon the tests, may be able to assess the point of
contamination
Could trace as far back as the agriculture production of the food
If the common source was prepared in several kitchens, by
several people, would suggest an upstream point of
contamination
Can conduct environmental assessments, looking for related
pathogen
Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak

6. Deciding an outbreak is over
Once a point of contamination is identified, control measures
should be implemented immediately
Could include…
Clean/disinfect facilities
Temporarily close restaurant/plant
Recalling food items
Educate the public
Dispose of particular items
Investigating Foodborne Outbreaks
Detecting a possible outbreak
Defining and finding cases
Generating hypotheses about likely sources
Testing the hypotheses
Finding the point of contamination
Controlling an outbreak
Deciding an outbreak is over
An outbreak ends when the number of new illnesses drops back
to the normal baseline (remember Step 1)
Continue to conduct surveillance in case new cases arise
In which case, the investigation would be reopened and
hypotheses may need to be revised or retested
PulseNet – Identifying Outbreaks
National laboratory network of 83 public health laboratories
Uses “fingerprinting” of microorganisms – either by DNA or
patterns of bacteria
Pulse-field gel electrophoresis (PFGE)
Whole genome sequencing (WGS)
Used for several foodborne illnesses – E. coli, Salmonella,
Shigella, Vibrio cholera, and more…

7. Blue Bell & Listeria
February 2015 – South Carolina Department of Health and
Environmental Control found listeria as part of routine sampling
of products
Based on this, Texas Department of State Health Services
collected product samples from the Blue Bell Creameries
facility in Brenham, Texas – found the bacteria in the same
products identified in South Carolina
March 2015 – Kansas health officials identified the same PFGE
pattern in two cases
These two cases and four other cases developed in the hospital,
after patients ate the products containing listeria
March 13, 2015 – Blue Bell removed and recalled the product in
question and shut down the production line in the Brenham,
Texas facility
April 2015 – PulseNet database identified 6 more cases across 3
states with the same PFGE pattern
Linked these cases to the Blue Bell Oklahoma facility
April 20, 2015 – Blue Bell recalls ALL of its products from all
of its facilities

8. Blue Bell & Listeria
Shiga Toxin-producing E. Coli
Shiga Toxin-producing Escherichia coli (STEC)
Common strains are O157:H7 and O104:H4
Shiga Toxin – halts protein synthesis within target cells by
targeting the ribosomes
Similar to mechanism of ricin
2015 Chipotle Outbreak – E. Coli O26 (STEC)
Non-pathogenic strains are part of the normal flora in animals
and humans
Symptoms (~8 days):
Abdominal pain
Diarrhea (watery and/or bloody)
No or low-grade fever
Sources:
Undercooked meat
Has also been associated with alfalfa, fruit juices, salami,
lettuce, cheese, game meat, and raw milk
2015 Chipotle Outbreak – E. Coli O26 (STEC)

9. Outbreak in Washington and Oregon in late 2015
Most likely associated with one food item (but never identified)
October 31, 2015 – WA & OR officials announce an outbreak
linked to Chipotle food
November 3, 2015 – Chipotle closes 43 restaurants in WA & OR
November 20, 2015 – The CDC expands the scope to six states,
affected at least 45 people
December 4, 2015 – The CDC again expands the scope to 9
states and 52 people
Finally, outbreak was expanded to 11 states and 55 people
2015 Chipotle Outbreak – E. Coli O26 (STEC)
Outbreak in Washington and Oregon in late 2015
Most likely associated with one food item (but never identified)
October 31, 2015 – WA & OR officials announce an outbreak
linked to Chipotle food
November 3, 2015 – Chipotle closes 43 restaurants in WA & OR
November 20, 2015 – The CDC expands the scope to six states,
affected at least 45 people
December 4, 2015 – The CDC again expands the scope to 9
states and 52 people
Finally, outbreak was expanded to 11 states and 55 people
2015 Chipotle Outbreak – E. Coli O26 (STEC)
Whole genome sequencing was conducted on 36 of the STEC
O26 isolates (from the 55 individuals identified)
All 36 isolates were closely related genetically
Provided additional evidence that the illnesses were linked to a
common source

10. 2015 Chipotle Outbreak – E. Coli O26 (STEC)
Another outbreak occurred in December 2015
Five people identified in 3 states
However, whole genome sequencing determined that the STEC
O26 strain was not related to the initial, larger outbreak
Additional Norovirus outbreaks in 2015 compounded the food
safety concerns at Chipotle Mexican Grill
Hepatitis A Virus (HAV)
One of the five known hepatitis viruses – A, B, C, D, & E
Both HAV and HEV are spread by the fecal-oral route (making
them foodborne)
Unlike HBV and HCV, which are bloodborne (HDV is
associated with HBV only)
Why are they called hepatitis?
These viruses affect the liver (Greek – Hepar; root – hepat-)
Symptoms of HAV (usually lasts ~ 8 weeks)
Nausea, vomiting, diarrhea
Jaundice
Fever
Abdominal pain
May result in acute liver failure
Global Distribution of HAV
Red – High prevalence (>8%)
Orange – Intermediate (2-8%)
Grey – Low (>2%)
Red – high (above 8% prevalence)

11. 30
Why?
HAV Clinic at Daycare in Houston
In 2014, the City of Houston had a case of HAV in a church-
based daycare worker in Northeast Houston
Why was this particularly concerning?
Post-exposure prophylaxis (PEP) is effective within 2 weeks of
exposure
HAV Vaccine – for those 12 months-40 years
HAV Immune Globulin (antibodies to HAV; harvested from
plasma) – for those less than 12 months, over 40 years, or other
indication
Houston Health Department officials provided a clinic at the
church-based daycare in NW Houston
Asked that all contacts (mostly children) of the infected
individual come to the clinic to receive PEP
Prion Diseases
Progressive neurological disorders
Caused by prions
Prions are infectious, misfolded proteins
Often transmitted through food
Made of Prion Protein (PrP)
PrP is found in the membranes of cells throughout the body
PrPC – Normal PrP
PrPSc – Infectious, isoform of PrP; able to convert other PrP
molecules
Mechanism for the infectious nature of prions is not entirely

12. understood
Bovine Spongiform Encephalopathy (BSE)
Also known as “mad cow disease”
Causes a spongiform degeneration of central nervous system
Has a long incubation period – 2.5 to 5 years
Can be transmitted to humans through consuming affected meat
(though most highly concentrated in CNS tissues, it is found
throughout body)
When transmitted, it’s known as Variant Creutzfeldt-Jakob
Disease (vCJC)
Bovine Spongiform Encephalopathy (BSE)
Affected over 300,000 cattle in France, 180,000 in the UK
Caused by cattle being fed meat and bone meal (MBM) of other
cattle
In the UK, over 4.4 million cows slaughtered
Estimated that almost 500,000 BSE-infected animals had
entered the food chain before controls were introduced in 1989
Remains viable to temperatures over 600 degrees Celcius
By June 2014, killed 177 people in the UK and 52 elsewhere in
Europe

13. Still no cure for vCJD
Kuru
Formerly common among the Fore people of Papua New Guinea
“Kuru” refers to the word “kuria” or “guria”, meaning “to
shake”, characteristic of the trembling caused by the disease
Also caused by prions
Transmitted through funerary cannibalism
Most prevalent among women and children, who generally ate
the brain of the deceased individual
Practice stopped about 50 years ago, but with a long incubation
period (10-50 years), the disease lingered
Declined from ~200 deaths in 1957 to 1 death in 2005
Genetically Modified Food
What do we know or think about genetically modified food?
Demand for food is ever-increasing with growing world
population
Refers to food that has been manipulated genetically
(recombinant DNA technologies) to increase productivity
Herbicide-resistance
Ability to grow in poor-quality soils
Increase resistance to insects
Improve nutritional value
Increase resistance to disease
Land area (millions of hectares) used for GM crops by country

14. Genetically Modified Food
Despite concern over potential consequences, genetically
modified food has been found to be generally safe
General consensus within science that genetically modified
crops are no more dangerous than conventional crops
In fact, likely more nutritious and safer
Regulations vary by nation, with many European countries
having a “de facto” ban on genetically modified food between
1999 and 2004
19 European countries (of 38 worldwide) ban genetically
modified crops
Developing regions grow over 50% of genetically modified
crops
Questions?