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Agents of Foodborne Zoonoses• Illness caused by
– Campylobacter spp.– Escherichia coli O157:H7– Salmonella
• 80-95% cases from these bacteria estimated tobe foodborne; probably of animal origin
• FoodNet data (repeat???)– PulseNet: Molecular epidemiology
• Outbreaks and investigations• Carriage by food animals and food• Risk
Foodborne Diseases ActiveSurveillance Network (FoodNet)
• Principal foodborne disease component ofCDC's Emerging Infections Program
• Active surveillance for foodborne diseases andrelated epidemiologic studies (PulseNet) tobetter understand the epidemiology of foodbornediseases in the United States.
• “Active” surveillance system, meaning publichealth officials frequently contact laboratorydirectors to find new cases of foodbornediseases and report these cases electronically toCDC.
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 fivelocations: California, Connecticut, Georgia,Minnesota and Oregon
• New York and Maryland in 1998,Tennessee in 2000, Colorado in 2001 andNew Mexico in 2004).– The total population of the 2004 bacterial
catchment is 44.5 million persons, or 15.1% ofthe United States population.
Mead et al (1999)
Reported and Estimated Illnesses:Foodborne pathogens--US
Mead et al (1999)
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Foodborne Disease - US (1998-2002)(Reported)
From FoodNet and Mead et al (1999)
(Estimated)
Relative Rates vs 1996-1998 Baseline
FoodNet
FoodNet 2006
FoodNet
Incidence/105
Outbreaks 1998-2002
After FoodNet Kimura et al (2004)
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After FoodNet
Campylobacteriosis
FoodNet
Campylobacteriosis
http://www.cdc.gov/foodnet/annual/2004/Tables.pdf
All Sites California
Foodborne Illness Cases(Top 10 Salmonella Serotypes)
FoodNet
Reported Outbreaks and Cases—US (1998)
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Outbreak Investigations
• Subtyping• PulseNet• E. coli O157
– Hamburger– Spinach
• Salmonella• Campylobacter
– Manning et al (2003)
Subtyping• 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)
Methods used for typingE. coli O157:H7 strains
• Toxin gene screening
• Plasmid profiling
• Phage typing
• Antibiotic susceptibility testing
• Restriction fragment lengthpolymorphism with bacteriophageλ (λ -RFLP)
• Ribotyping;• Pulsed-field gel electrophoresis• PCR using randomly amplified
polymorphic DNA (RAPD)sequences
• PCR using highly repetitivesequences (rep-PCR)
• Amplified fragment lengthpolymorphism analysis
• Thomas et al., 1996; Ostroff et al.,1989
• Ostroff et al., 1989; Paros et al., 1993;Meng et al., 1995; Radu et al., 2001
• Ahmed et al., 1987; Khakhria et al.,1990; Barrett et al., 1994
• Kim et al., 1994; Farina et al., 1996;Radu et al., 2001;
• Paros et al., 1993;Samadpour et al.,1993
• Martin et al., 1996; Roberts et al., 2001• Bohm and Karch, 1992;Barrett et al.,
1994;Meng et al., 1995;Radu et al.,2001
• Swaminathan and Barrett,1995; Raduet al., 2001
• None specific for E. coli-O157:H7;Johnson and O’Bryan, 2000
• Iyoda et al., 1999; Zhao et al., 2000
How Does PulseNet Work?1. PFGE2. Pattern electronic database at local,
state or federal level3. Uploaded to national database at CDC4. CDC searches for clusters of patterns5. Local cluster searches6. Clusters posted to Listserve.
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Changes in Outbreaks
• Food consumption and practices in UShave changed during the past 20 years
• Shift from the typical point source, or“church supper” outbreak, which isrelatively easy to detect to the morediffuse, widespread outbreaks that occurover many communities with only a fewillnesses 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 outbreakdetection algorithm (SODA), impact ability toidentify and investigate these new types ofoutbreaks
How does subtyping help inepidemiologic 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)
outbreakdetected 1993
Meat recall
1993 Western States E. coli O157 Outbreak
732 cases4 deaths
39 d
outbreak detected 2002
18 d
Swaminathan
Prevalence in Food Products
• E. coli O157:H7– Beef– Fruits and vegetables
• Salmonella– Poultry, beef, hogs– Eggs, fruits, vegetables
• Campylobacter– Poultry
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Fresh ProduceOutbreaks--US
(1977-1999)
Sivapalasingam et al. (2004)
Some pathogenic E. coli(Simplified)
LT/STenterotoxigenic stx+
eae+
EHEC
O157:H7
E. coli
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
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MMWR
SalmonellaFarm and Processing Plant
McCrea et al. (2006)
Salmonella poona: Cantaloupes
• April—June 2000– 47 cases; 5 states
• April—May 2001– 50 cases; 5 states
• March—May 2002– 58 cases; 14 states and provinces
Anderson et al. (2002)
PR/HACCP Salmonella “A” Sets(1998-2006)
After: http://www.fsis.usda.gov/science/Progress_Report_Salmonella_Testing_Tables/index.asp
PR/HACCP Salmonella “A” Sets
http://www.fsis.usda.gov/PDF/Salmonella_9year_Figures.pdf Sarwari et al. (2001)
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Broilers Ground Turkey
Hogs Ground Beef
Rigney et al. (2004)
1998-2000
Heinitz et al (2000)
CampylobacterFarm and Processing Plant
McCrea et al. (2006)
Campylobacteriosis in Iceland
Stern et al. (2003)
Campylobacter Prevalence (US)Chicken Carcass Rinses
Stern and Pretanik (2006)
20042003
0
0
0
Campylobacter Prevalence (US)Chicken Carcass Rinses
Stern and Pretanik (2006)
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Risk Factors
• Mostly exposure to food• Exposure to animals
Risk Factors S. enteric serotypeEnteritidis (FoodNet 02-03)
Marcus et al. (2006)
Friedman et al (2004)
Transfer of Campylobacter
Luber et al. (2006)
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E. coli O157:H7 Risk Factors(FoodNet 1999-2000)
Voetsch et al (2006)