Introduction of Hazards:Preparation, Consumption, and the Chain of

Transmission

Pathogen Reduction DialoguePanel 1

May 6, 2002Georgetown University Conference Center

Robert V Tauxe, M.D., M.P.H.Foodborne and Diarrheal Diseases Branch,

DBMD, NCIDCenters for Disease Control and Prevention,

Atlanta, GA

Each year an estimated 76 million cases• 1 in four Americans gets a foodborne illness each year• 1 in 1000 Americans is hospitalized each year• $6.5 billion in medical and other costs

• Prevention depends on efforts from farm to table to reduce contamination of food

Public health burden of foodborne disease

Infection with a variety of different pathogens

Illness may occur in large focal outbreaksMost illness is “sporadic”: either individual cases or part of

unrecognized dispersed outbreaks

Reservoir: locus of sustained transmission and persistence• Some have a human reservoir: Shigella, hepatitis A, Norwalk virus

• Some have an animal reservoir: Salmonella, Campylobacter, E. coli O157:H7, Listeria, Vibrio, Yersinia, Toxoplasma

Often transmitted by several different pathways• Specific foods, water, direct contact with animals, direct contact with humans

Foodborne diseases

Major identified foodborne pathogens, United States – circa 2002

• Bacterial: Bacillus cereus Brucella Campylobacter* Clostridium botulinum Clostridium perfringens E. coli O157:H7* E. coli, non-O157 STEC* E. coli, other diarrheagenic* Listeria monocytogenes* Salmonella Typhi Salmonella non-typhoidal Shigella Staphylococcus Streptococcus Vibrio cholerae, toxigenic*

• Bacterial, continued: Vibrio vulnificus* Vibrio, other* Yersinia enterocolitica*

• Parasitic: Cryptosporidium* Cyclospora* Giardia* Toxoplasma* Trichinella

• Viral: Norwalk-like viruses* Rotavirus* Astrovirus* Hepatitis A

* Recognized as foodborne in last 30 years

Prions*

Major identified foodborne pathogens, United States – circa 2002

• Bacterial: Bacillus cereus Brucella Campylobacter* Clostridium botulinum Clostridium perfringens E. coli O157:H7* E. coli, non-O157 STEC* E. coli, other diarrheagenic* Listeria monocytogenes* Salmonella Typhi Salmonella non-typhoidal Shigella Staphylococcus Streptococcus Vibrio cholerae, toxigenic*

• Bacterial, continued: Vibrio vulnificus* Vibrio, other* Yersinia enterocolitica*

• Parasitic: Cryptosporidium* Cyclospora* Giardia* Toxoplasma* Trichinella

• Viral: Norwalk-like viruses* Rotavirus* Astrovirus* Hepatitis A

* Recognized as foodborne in last 30 years (Zoonotic reservoir)

Prions*

The new foodborne zoonoses

The infected food animal looks healthySustained or repeated infections in animalsContaminated food looks normalPathogen survives standard processing

and preparationMissed by current inspection strategiesSpreads silently around the globeRequires new control strategies

More to be discovered

The chain of production from farm to table: A generic scenario

Production

Processing

Final preparationand cooking

Farm, Feedlot,Fishing site

Slaughter Plant, Cannery,Packer, Food Factory

Final Kitchen: commercial, institutional or domestic

The chain of production from farm to table: A generic scenario

Production

Processing

Final preparationand cooking

Farm, Feedlot,Fishing site

Slaughter Plant, Cannery,Packer, Food Factory

Final Kitchen: commercial, institutional or domestic

What happens in kitchens?

1993-1997: Among 2,751 foodborne outbreaks reported to CDC, 43% in restaurants/delis/etcContributing kitchen factors noted

73% - poor holding temperatures38% - poor personal hygiene21% - inadequate cooking

1980-1995: New York State: 1806 outbreaks: 32% - contaminated ingredients24% - consumption of raw/lightly heated23% - food from unapproved source23% - ill food handler

Outbreaks are multi-factorial events

Problems in food handling are often reported in foodborne outbreak investigations

Probably frequent in kitchens where an outbreak has not occurred

Training focused on better food handling important, so is handwashing

Reducing the arrival of the pathogens into kitchen is also important

Introduction of pathogens into food during final preparation: what are the

sources?

Foods arrive contaminated (particularly raw foods of animal origin)

Food handler infected with the pathogen

Other environmental sources

When contaminated raw foods of animal origin arrive in the kitchen,

Handling may further amplify risk

Easily cross-contaminate other foods via hands, utensils, surfaces

A direct risk if undercooked (FoodNet 2000 survey)

•Raw oysters - 2.5% in preceding month•Pink ground beef - 26% •Runny egg dish - 27%

3% use a thermometer for burgers

When an ill food handler arrives in the kitchen,

They work, because they have no paid sick leave

They may be shedding the organism in feces or vomit

Lapses in personal hygiene can contaminate food

Particularly for pathogens with human reservoir:Norwalk-like viruses, Shigella, hepatitis A

Occasionally for pathogens with animal reservoirs:Salmonella, E. coli O157, Campylobacter

Food may be contaminated by other environmental sources

Food prepared or consumed around animals•Petting zoos, county fairs, “barn dances”•Large E. coli O157 outbreak, U Wisconsin, 2001

34 cases after a breakfast in the stock pavilion

Food prepared with contaminated water

Rodents, insects, and other vermin maycross-contaminate food

Prevention strategies for the general public to reduce contamination in the

kitchen

Basic food safety educationAvoid risky food practicesSeparate handling raw meat and infant carePurchase foods processed for safety:

•Pasteurized milk, juice•Pasteurized shell eggs•Irradiated ground beef

Ask restaurants about their sick leave policies

Prevention strategies for food establishments to reduce contamination

in the kitchen

Basic food safety training and certificationPaid sick leave policiesMake handwashing easy and frequentReduce contact with ready to eat food

Include pathogen reduction standards in purchase contracts

For institutional kitchens serving high risk populations, foods processed for

safety are available now

Pasteurized shell eggs and liquid eggs to avoid Salmonella Enteritidis infections

Irradiated ground beef to avoid E. coli O157:H7 and Salmonella infections

Frozen chicken and turkey, to reduce risk of Campylobacter infections

Food safety education is important but not sufficient to protect public health

Raw foods of animal origin are often contaminatedSerious infections, grave complicationsTraditional recipes call for limited cooking

•Raw oysters, rare ground beef, soft boiled eggs, hollandaise sauce

Hard to tell when food is thoroughly cooked •Boiled eggs, baked lasagna, “browned” burgers

Raw meat, poultry, eggs in the kitchen is handled by someone also handling other foodsFresh produce, rinsed and eaten without cooking

The chain of production from farm to table: Where contamination can occur

Production

Processing

Final preparationand cooking

Feed, water, manure, wildlife, new stockLairage, water baths,Manure, sanitation, cross contamination

Time, temperature,Cross-contamination,Worker health, hygiene

• Pathogens:

• Campylobacter• E. coli O157:H7• Salmonella• Yersinia

• Listeria monocytogenes

• Norwalk-like viruses• Hepatitis A

• Sources:

• Poultry, production level• Cattle, production level,• Poultry, cattle, pig, produce, production level• Pigs, production level

• Ready to eat meats, processing level

• Humans, production and preparation level• Humans, production and preparation level

Principle sources of pathogens

The chain of production from farm to table: Where contamination can occur

Production

Processing

Final preparationand cooking

LandAnimals

Plants Fish and shellfish

Meat, poultry,dairy, eggs

Fruits, nuts,vegetables

Seafoods

The chain of production from farm to table: Where contamination can occur with

Vibrio parahaemolyticus

Production

Processing

Final preparationand cooking

LandAnimals

Plants Fish and shellfish

Meat, poultry,dairy, eggs

Fruits, nuts,vegetables

Seafoods

Shellfish in their beds

Shellfish in their beds

The chain of production from farm to table: Where contamination can occur with

Norwalk like viruses

Production

Processing

Final preparationand cooking

LandAnimals

Plants Fish and shellfish

Meat, poultry,dairy, eggs

Fruits, nuts,vegetables

Seafoods

Ill humansIll humans

The chain of production from farm to table: Where contamination can occur with

zoonotic Salmonella

Production

Processing

Final preparationand cooking

LandAnimals

Plants Fish and shellfish

Meat, poultry,dairy, eggs

Fruits, nuts,vegetables

Seafoods

Carrier food animals

Carrier food animals

The chain of production from farm to table: Prevention possible at many points

Production

Processing

Final preparation

and cooking

{Pathogen Killing Step}

On-farm sanitation, safety ofanimals' food and waterbiosecurity, and other"Good Agricultural Practices"

Factory sanitation, quality controlHACCP, microbial verification, inspection and other "Good Manufacturing Processes"

Food handler training, handwashing, sick leave, Restaurant inspection, Consumer education

Pasteurization, retort canning, irradiation

Schematic map of food industry

Production

Processing

Preparation

Land animals Plants

Seafood

Fish & shellfish

Meat, poultry, dairy,eggs

Fruit, nuts& vegetables

Distribution

Transport/ lairage

Consumption (and foodborne illness)

HACCP HACCP

0

1

2

3

4

5

6

7

8

1998 1999 2000 2001

Per

cen

t p

osit

ive

Large Small Very small

HACCP monitoring samples (FSIS data). Percent of ground beef samples yielding Salmonella, by size of

processing plant, and year Baseline

0

10

20

30

40

1998 1999 2000 2001

Per

cen

t p

osit

ive

Broilers Ground turkey Hogs

HACCP monitoring samples. Percent of broiler, ground turkey and hog samples yielding Salmonella,

by year, large processing plants (FSIS data)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1996 1997 1998 1999 2000 2001

Rel

ativ

e R

ate

Salmonella Campylobacter Listeria Yersinia

Human illness data (CDC-FoodNet). Change in incidence of foodborne infections relative to 1996

15%25%31%49%

Decrease of

Some future prevention points for foodborne disease (with microbial

validation)

E,HW,SL

Production

Processing

Preparation

Land animals Plants

Seafood

Fish & shellfish

Meat, poultry, dairy,eggs

Fruit, nuts& vegetables

Distribution

Transport/ lairage

Consumption (and foodborne illness)

HACCP HACCP

QAP

Some future prevention points for foodborne disease (with microbial

validation)

E,HW,SL

Production

Processing

Preparation

Land animals Plants

Seafood

Fish & shellfish

Meat, poultry, dairy,eggs

Fruit, nuts& vegetables

Distribution

Transport/ lairage

Consumption (and foodborne illness)

HACCP HACCPHACCP

QAP

Foodborne pathogens enter food chain at multiple points Pathogen reduction approaches can reduce risk at each stepMicrobial monitoring can verify control measuresIn the kitchen:

• Educating the food preparers is important, so is• Handwashing• Keeping ill workers out of the kitchen, and• Decreasing contamination of food coming into the kitchen

Microbial standards in purchase contracts may helpFor high risk populations, using safer food products

Summary