Food Contamination

Introduction of Hazards: Preparation, Consumption, and the Chain of Transmission Pathogen Reduction Dialogue Panel 1 May 6, 2002 Georgetown University Conference Center Robert V Tauxe, M.D., M.P.H. Foodborne and Diarrheal Diseases Branch, DBMD, NCID Centers for Disease Control and Prevention, Atlanta, GA

Public health burden of foodborne disease 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

Foodborne diseases Infection with a variety of different pathogens Illness may occur in large focal outbreaks Most 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

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 healthy Sustained or repeated infections in animals Contaminated food looks normal Pathogen survives standard processing and preparation Missed by current inspection strategies Spreads silently around the globe Requires new control strategies More to be discovered

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

Final preparation and 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 Productio n Processing

Final preparation and 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/etc Contributing kitchen factors noted 73% - poor holding temperatures 38% - poor personal hygiene 21% - inadequate cooking 1980-1995: New York State: 1806 outbreaks: 32% - contaminated ingredients 24% - consumption of raw/lightly heated 23% - food from unapproved source 23% - 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 may cross-contaminate food

Prevention strategies for the general public to reduce contamination in the kitchen Basic food safety education Avoid risky food practices Separate handling raw meat and infant care Purchase 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 certification Paid sick leave policies Make handwashing easy and frequent Reduce 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 contaminated Serious infections, grave complications Traditional 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 foods Fresh produce, rinsed and eaten without cooking

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

Final preparation and cooking

Feed, water, manure, wildlife, new stock Lairage, water baths, Manure, sanitation, cross contamination Time, temperature, Cross-contamination, Worker health, hygiene

Principle sources of pathogens • Pathogens: • • • •

Campylobacter E. coli O157:H7 Salmonella Yersinia

• Sources: • • • •

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

• Listeria monocytogenes • Ready to eat meats, processing level • Norwalk-like viruses • Hepatitis A

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

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

Land Animals

Plants

Fish and shellfish

Processing

Final preparation and cooking

Meat, poultry, Fruits, nuts, Seafoods vegetables dairy, eggs

The chain of production from farm to table: Where contamination can occur with Vibrio parahaemolyticus Productio n

Land Animals

Plants

Shellfish Fish and in shellfish their beds

Processing

Final preparation and cooking

Meat, poultry, Fruits, nuts, Seafoods vegetables dairy, eggs

The chain of production from farm to table: Where contamination can occur with Norwalk like viruses Productio n

Land Animals

Plants

Fish and shellfish

Processing Ill humans

Final preparation and cooking

Meat, poultry, Fruits, nuts, Seafoods vegetables dairy, eggs

The chain of production from farm to table: Where contamination can occur with zoonotic Salmonella Productio n

Land food Carrier Animals animals

Plants

Fish and shellfish

Processing

Final preparation and cooking

Meat, poultry, Fruits, nuts, Seafoods vegetables dairy, eggs

The chain of production from farm to table: Prevention possible at many points Productio n Processing {Pathogen Killing Step} Final preparation and cooking

On-farm sanitation, safety of animals' food and water biosecurity, and other "Good Agricultural Practices" Factory sanitation, quality control HACCP, microbial verification, inspection and other "Good Manufacturing Processes" Pasteurization, retort canning, irradiation Food handler training, handwashing, sick leave, Restaurant inspection,

Schematic map of food industry Production

Land animals

Plants

Fish & shellfish Transport/ lairage

Processing

HACCP

HACCP Distribution

Preparation

Meat, poultry, Fruit, nuts dairy,eggs & vegetables

Consumption (and foodborne illness)

Seafood

HACCP monitoring samples (FSIS data). Percent of ground beef samples yielding Salmonella, by size of processing plant, and year 8 Percent positive

7

Baseline

6 5 4 3 2 1 0 1998

Large

1999

Small

2000

2001

Very small

Percent positive

HACCP monitoring samples. Percent of broiler, ground turkey and hog samples yielding Salmonella, by year, large processing plants (FSIS data) 40 30

20

10

0 1998

Broilers

1999

2000

Ground turkey

2001

Hogs

1.4

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

1.2

Decrease of 15% 25% 3 1%4 9%

Relative Rate

1 0.8 0.6 0.4 0.2 0 1996 Salmonella

1997

1998

Campylobacter

1999

2000

Listeria

2001 Yersinia

Some future prevention points for foodborne disease (with microbial validation) Production

Processing

Preparation

Land animals

Plants

QAP

Transport/ lairage

HACCP

HACCP

E,HW,S Meat, poultry, Fruit, nuts L dairy,eggs

Fish & shellfish

& vegetables

Consumption (and foodborne illness)

Distribution Seafood

Some future prevention points for foodborne disease (with microbial validation) Production

Processing

Preparation

Land animals

Plants

QAP HACCP

Transport/ lairage

HACCP

E,HW,S Meat, poultry, Fruit, nuts L dairy,eggs

Fish & shellfish

& vegetables

Consumption (and foodborne illness)

HACCP Distribution Seafood

Summary Foodborne pathogens enter food chain at multiple points Pathogen reduction approaches can reduce risk at each step Microbial monitoring can verify control measures In 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 help For high risk populations, using safer food products