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Summarize these slides in 3-4 paragraphs. 4 would be great

Chapter 11 Discussion

Summarize these slides in 3-4 paragraphs. 4 would be great 

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 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

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

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…

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

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)

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

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)

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 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

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

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?

 

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