Agents of Foodborne Zoonoses• Illnesses caused by

– Campylobacter spp.– Escherichia coli O157:H7– Salmonella

• 80-95% cases from these bacteria estimated to be foodborne; probably of animal origin

• FoodNet data (repeat)– PulseNet: Molecular epidemiology

• Outbreaks and investigations• Carriage by food animals and food• Risk

Foodborne Diseases Active Surveillance Network (FoodNet)

• Principal foodborne disease component of CDC's Emerging Infections Program

• Active surveillance for foodborne diseases and related epidemiologic studies (PulseNet) to better understand the epidemiology of foodborne diseases in the United States.

• “Active” surveillance system, meaning public health officials frequently contact laboratory directors to find new cases of foodborne diseases and report these cases electronically to CDC.

FoodNet Disease Monitoring• Bacteria

– Campylobacter– Escherichia coli O157– Listeria monocytogenes– Salmonella– Shigella– Vibrio– Yersinia enterocolitica

• Parasites– Cryptosporidium– Cyclospora

• Viruses– Hepatitis A– Noroviruses

FoodNet

• 1995, FoodNet surveillance began in five locations: California, Connecticut, Georgia, Minnesota and Oregon

• New York and Maryland in 1998, Tennessee in 2000, Colorado in 2001 and New Mexico in 2004). – The total population of the 2004 bacterial

catchment is 44.5 million persons, or 15.1% of the United States population.

Mead et al (1999)

Reported and Estimated Illnesses: Foodborne pathogens--US

Mead et al (1999)

Foodborne Disease - US (1998-2002)(Reported)

From FoodNet and Mead et al (1999)

(Estimated)

Relative Rates vs 1996-1998 Baseline

http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5714a2.htm

Vibrio

Listeria

SalmonellaCampylobacter O157

Outbreaks 1998-2002

0

5

10

15

20

25

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Pe

rce

nt

OB

/Mo

nth

Campylobacter (61)

E. coli (140)

Salmonella (585)

After FoodNet

Campylobacteriosis (1996-1999)

0

10

20

30

40

50

60

70

1996 1997 1998 1999

Inci

den

ce/1

05

California

Connecticut

Georgia

Minnesota

Oregon

After FoodNet

Campylobacteriosis

Campylobacteriosis 1996-1999

0

10

20

30

40

50

60

<1 1–4

5–9

10–1

4

15–1

9

20–2

9

30–3

9

40–4

9

50–5

9>6

0

Age (Years)

Inci

den

ce/1

05

FoodNet

Foodborne Illness Cases(Top 10 Salmonella Serotypes)

FoodNet

www.fsis.usda.gov/PDF/Serotypes_Profile_Salmonella_Tables_&_Figures.pdf

Frequency of some Salmonella SerotypesIsolated from some Commodities

Kimura et al (2004)

Foodborne Disease Outbreak Investigations

• Reported foodborne outbreaks (FoodNet)• Subtyping• PulseNet• E. coli O157:H7

– Hamburger– Spinach

• Salmonella– Peanuts– Pistachios (3/30), spices (4/2)

• Campylobacter– Poultry

Reported Outbreaks and Cases—US (1998)

Subtyping Issues

• ID cases likely to be part of an outbreak• Eliminate sporadic cases (background noise)• Difficult to select appropriate method

– Tenover et al. (1997)

• Salmonella– Bender et al (2001)– McQuiston et al (2004)

• E. coli O157:H7– Samadpour (1995)

• Campylobacter– Manning et al (2003)

Some Methods Used for Typing E. coli O157:H7 Strains

Toxin gene screening Thomas et al., 1996; Ostroff et al., 1989

Plasmid profiling Ostroff et al., 1989; Paros et al., 1993; Meng et al., 1995; Radu et al., 2001

Phage typing Ahmed et al., 1987; Khakhria et al., 1990; Barrett et al., 1994

Antibiotic susceptibility testing Kim et al., 1994; Farina et al., 1996; Radu et al., 2001;

Restriction fragment length polymorphism with phage λ (λ -RFLP)

Paros et al., 1993;Samadpour et al., 1993

Ribotyping Martin et al., 1996; Roberts et al., 2001

Pulsed-field gel electrophoresis (PFGE) Bohm and Karch, 1992;Barrett et al., 1994;Meng et al., 1995;Radu et al., 2001

PCR using randomly amplified polymorphic DNA (RAPD) sequences

Swaminathan and Barrett,1995; Radu et al., 2001

PCR using highly repetitive sequences (rep-PCR)

None specific for E. coli-O157:H7; Johnson and O’Bryan, 2000

Amplified fragment length polymorphism analysis (AFLP)

Iyoda et al., 1999; Zhao et al., 2000

How Does PulseNet Work?

1. PFGE

2. Pattern electronic database at local, state or federal level

3. Uploaded to national database at CDC

4. CDC searches for clusters of patterns

5. Local cluster searches

6. Clusters posted to Listserve.

Changes in Outbreaks

• Food consumption and practices in US have changed during the past 20 years

• Shift from the typical point source, or “church supper” outbreak, which is relatively easy to detect to the more diffuse, widespread outbreaks that occur over many communities with only a few illnesses in each community.

Changes in OutbreaksContinued• Large food producing facilities that disseminate

products throughout the country• Some few outbreaks that some low level

contamination of food products• Products are distributed among many states• Only a few illnesses occur in each community, • New laboratory and statistical tools, such as

PulseNet and the surveillance outbreak detection algorithm (SODA), impact ability to identify and investigate these new types of outbreaks

How does subtyping help in epidemiologic investigations?

• Identifies cases within an outbreak • Distinguishes outbreak cases from concurrent

sporadic cases• Reduces misclassification• Detects outbreaks through surveillance• Links apparently sporadic cases

– Cases may be too widely dispersed to detect– Organism too common to notice small increase– Identifies related cases and separates them from unrelated

ones

• DNA “fingerprinting” methods have greatly increased sensitivity of subtyping

Increases sensitivity of outbreak detection

Rangel, J.M. et al. Emerg. Infect. Dis. 11: 603-609 (2005)

Num

ber

of

Out

brea

ks/Y

ear

0

10

20

30

40

50

60

70

1 8 15 22 29 36 43 50 57 64 71

Day of Outbreak

Nu

mb

er o

f C

ases outbreak

detected 1993Meat recall

1993 Western States E. coli O157 Outbreak

732 cases4 deaths

39 d

2002 Colorado E. coli O157 Outbreak

0

10

20

30

40

50

60

70

1 8 15 22 29 36 43 50 57 64 71

Day of Outbreak

Nu

mb

er o

f C

ases

outbreak detected 2002

18 d

Swaminathan

Occurence in Food Products

• E. coli O157:H7– Beef– Fruits and vegetables

• Salmonella– Poultry, beef, hogs– Eggs, fruits, vegetables, nuts

• Campylobacter– Poultry

Fresh Produce Outbreaks--US

(1977-1999)

Sivapalasingam et al. (2004)

Some Pathogenic E. coli(Simplified)

LT/STenterotoxigenic

stx+

eae+

EHEC

O157:H7

E. coli Verotoxin =

Shigatoxin

stx Assay on Vero CellsFiltrate Control

Speirs et al (1977)

E. coli O157:H7 Outbreak--1993

• Western states

• >500 laboratory-confirmed infections

• 4 deaths

• O157:H7 known in hamburger since 1982– Wells et al. (1983)

• Prompted FSIS to declare O157:H7 an adulterant in raw ground beef (1994)– Product often undercooked

Leafy Greens Outbreaks

Buchanan

MMWR

MMWR

Sarwari et al. (2001)

Broilers Ground Turkey

Hogs Ground Beef

Rigney et al. (2004)

1998-2000

Salmonella Farm and Processing Plant

McCrea et al. (2006)

Heinitz et al (2000)

CampylobacterFarm and Processing Plant

McCrea et al. (2006)

Strains

Campylobacter Prevalence (US)

Top: Stern and Pretanik (2006); Bottom: FoodNet

20042003

0

10

20

30

40

50

Sep OctNov Dec Ja

nFeb M

ar AprM

ay Jun

Jul

Aug Sep

Pe

rce

nt

Po

sit

ive

Sa

mp

les

0

5

10

15

20

25

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Pe

rce

nt

OB

/Mo

nth

Campylobacter (61)

E. coli (140)

Salmonella (585)

Chicken Carcass Rinses

Outbreaks

Campylobacter Prevalence (US)Chicken Carcass Rinses

0

10

20

30

40

50

Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

Pe

rce

nt

Po

sit

ive

Sa

mp

les

0.0

0.5

1.0

1.5

2.0

2.5

3.0

log

CF

U/C

arc

as

s

Prevelance

CFU/carcass

Stern and Pretanik (2006)

Risk Factors

• Mostly exposure to food

• Exposure to animals

Risk Factors S. enterica serotype Enteritidis (FoodNet 02-03)

Marcus et al. (2006)

Friedman et al (2004)

Transfer of Campylobacter

Luber et al. (2006)

E. coli O157:H7 Risk Factors(FoodNet 1999-2000)

Voetsch et al (2006)

Peanut Outbreak – 2008-09

FDA Press ReleaseJanuary 12, 2009

• Salmonella recovered from King Nut peanut butter• Minnesota Dept. Agriculture lab results• Genetic match to national cases• Strain associated with 30 illnesses in MN

– About 500 cases nationwide• Distributed to 7 states• Distributed in MN to:

– Long-term care facilities– Hospitals– Schools– Universities– Restaurants– Delicatessens– Cafeteria– Bakeries

>200 Manufacturers; 3882 Products

• Aspen Hills• Best Brands• Lovin Oven• Landies Candies• Weis Markets• Blanton’s Candies• Dinners Ready Meridian• Boca Grande Foods• Premier Nutrition• NutriSystem• Ready Pac Foods• PetSmart• Nature’s Path• Country Maid

• Evening Rise Bread• Clif Bar• Kroger• Abbott Nutrition• Meijer• Peanut Corp. Amer.• Ralcorp• South Bend Chocolate• McKee• Perry’s Ice Cream• Hy-Vee• Kellogg• King Nut

CDC Outbreak UpdateMarch 17, 2009

• 691 cases in 46 states; 8-9 related deaths

• Latest illness onset February 24, 2009

• To date, 16 clusters of infections in five states reported in schools and other institutions

• Among 14 clusters with detailed information, King Nut is the only brand of peanut butter used in those facilities.

http://www.cdc.gov/salmonella/typhimurium/map.html

http://www.cdc.gov/salmonella/typhimurium/epi_curve.html

The Epidemic Curve

• Progression of an outbreak over time.  • Epi curve is complex and incomplete. • Delay between onset and reported to

public health authorities.  – Typically takes 2-3 weeks for Salmonella

• Some background cases likely to occur without an outbreak.  – This makes it difficult to say exactly which

case is the first in an outbreak   

Salmonella Typhimurium OutbreakPeanut products: 2008-9

King Nut Peanut Butter

• Produced by Peanut Corporation of America (PCA), a small, family-owned and operated business. HQ in Lynchberg, VA.

• Plant positive for Salmonella in Blakely, GA. <50 employees• No longer producing any products• Expanded recall to include all peanut butter and peanut

paste produced at this plant since July 1, 2008. • Peanut butter and peanut butter paste was not sold directly

to consumers– Distributed to institutions, food service providers, food manufacturers

and distributors in many states, Canada, Korea, and Haiti. – Peanut butter and peanut paste is commonly used in many products,

including cookies, crackers, cereal, candy, ice cream and others.

Questions?