Changing Epidemiological Trends and the Public Health Picture

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Changing Epidemiological Trends and the Public
Health Picture
November 16, 2004 Foodborne and Waterborne
Infectious Disease Threats Emory
University Robert V Tauxe, M.D.,
M.P.H. Foodborne and Diarrheal Diseases
Branch, Centers for Disease Control and
Prevention, Atlanta, GA
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• The fall and rise of reported Salmonella
  infections in the United States, 1920-2002

Industrialization of our food supply Non typhi
Salmonella E coli O157H7 Campylobacter
Sewers, water treatment, pasteurization of milk
CDC, National Notifiable Diseases surveillance
data
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Public health burden of foodborne disease

• 1997 Estimate 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
• Prevention depends on efforts from farm to table
  to reduce contamination of food
• Healthy People Goals for 2010 50 reduction
  from 1997 baseline in incidence of infections
  with
• Salmonella
• Campylobacter
• E. coli O157
• Listeria monocytogenes
• Outbreaks caused by Salmonella Enteritidis

Mead, EID 5607, 1999
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Foodborne diseases Philosophy of prevention

• No vaccines for most of these pathogens
• Educating consumers, foodhandlers and producers
  is important, but not sufficient
• Groups at highest risk Young children, elderly,
  immunocompromised
• Contamination can occur from farm to table
• Understand mechanisms of contamination well
  enough to prevent it upstream from the consumer
• Targets Specific pathogen food combinations

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• Public health prevention,
• The cycle of continuous improvement

Surveillance
Epidemiologic investigation
Prevention measures
Applied Targeted Research
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Foodborne disease Pathogens, problems and
prevention

• Current measures provide adequate control
• Trichinosis in pigs
• Botulism in commercial canned foods
• Improved, but not adequate control of
• Salmonella Enteritidis in eggs
• E. coli O157 in ground beef
• Campylobacter in poultry
• Listeria monocytogenes in processed meats
• Little successful control of
• Multiply-resistant Salmonella (dairy reservoirs,
  ground beef)
• Produce-related problems tomatoes, lettuce,
  melons
• Vibrio ssp (raw oysters)
• Norovirus salads, oysters

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• 1) Prevention along farm-to-table continuum can
  control disease threats

Farm, Feedlot, Fishing site
Production
Processing
Slaughter Plant, Cannery, Packer, Food Factory
Final Kitchen commercial, institutional or
domestic
Final preparation and cooking
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Pathogens, problems and prevention

• Current measures provide adequate control
• Trichinosis in pigs
• Botulism in commercial canned foods
• Improved, but not adequate control of
• Salmonella Enteritidis in eggs
• E. coli O157 in ground beef
• Listeria monocytogenes in processed meats
• Campylobacter in poultry
• Little successful control of
• Multiply-resistant Salmonella (dairy reservoirs,
  ground beef)
• Produce-related problems tomatoes, lettuce,
  melons
• Vibrio ssp (raw oysters)
• Norovirus salads, oysters

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Specific challenges with making farm to table
prevention work

• Understand contamination well enough to prevent
  it
• Years of multi-disciplinary research
• Line up market signals, incentives and
  regulations
• Many foods become anonymous as processed
• When contamination is not preventable foods most
  likely to be contaminated should get pathogen
  elimination treatment
• thermal pasteurization (milk, eggs)
• Irradiation (ground beef)
• high pressure (raw oysters)
• Some animals should not be eaten at all (TB, BSE)

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Irradiated ground beef is here
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Salmonella Enteritidis

• Causes acute gastroenteritis, complicated by
  sepsis in elderly, immunocompromised
• 200,000 cases, 100 deaths annually in 1990s
• Dominant source of outbreaks has been the egg
• Applied research
• Reservoir egg-laying hens, lifelong ovarian
  infections
• Estimated 1/20,000 eggs are positive
• Risk factors on farm
• Getting chicks from a hatchery with SE
• Not cleaning and disinfecting between flocks
• Rodents may transfer SE from flock to flock

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• Controlling Salmonella Enteritidis in egg flocks

• Production
• Eliminate SE from breeder flocks
• Voluntary egg quality assurance programs on farms
• Divert eggs from positive farms to pasteurization
• Distribution
• Refrigerate eggs throughout distribution
  nationwide
• Preparation
• Educating high risk consumers to avoid raw eggs
• Educating chefs/institutions to use pasteurized
  egg
• In the Future
• Mandatory egg quality programs

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Reported outbreaks due to Salmonella Enteritidis,
by year, 1985-2003
Healthy People 2010 Goal
Year
Foodborne Outbreak Reporting System, CDC. 2003
is preliminary
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Controlling bacterial contamination of meat with
Hazard Analysis-Critical Control Point (HACCP)

• 1996 Introduction of general HACCP strategies
  for meat slaughter hygiene, replacing simple
  visual inspection
• Process controls and safety checkpoints
• Salmonella testing of final carcass as standard
• Focus on carcass -gt processes for cleaner
  carcasses
• Likely impact on Campylobacter, Salmonella
• Little change in E. coli O157
• Ground beef is made from trim (scraps)
• 2002 New HACCP guidance on E. coli O157 in
  ground beef
• Industry tests bins of trim before grinding,
  requires they be negative for O157 before
  grinding
• New incentive to reduce this pathogen in trim as
  well as carcasses

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FoodNet trends 1996-2003
Since 1996, significant decreases in Infections
with Salmonella -17 Campylobacter -28 E.
coli O157 - 42 Yersinia - 49
1996 1997 1998 1999 2000 2001
2002 2003Year
MMWR 53338-343, 2004

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FSIS Year-to-Year comparison of the number of
positives E. coli O157H7 plant and retail
samples when controlling for season in a Poisson
regression model
p 0.03
p 0.32
p 0.89
Holt, ICEID, Atlanta 2004
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• Incidence of reported cases and outbreaks of
  listeriosis in the United States, 1986-2003

Multistate outbreak
PulseNet begins subtyping Listeria
Single state outbreak
Data from active surveillance systems, Some
data are preliminary
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2) New problems emerge

• Current measures provide adequate control
• Trichinosis in pigs
• Botulism in commercial canned foods
• Improved, but not adequate control of
• Salmonella Enteritidis in eggs
• E. coli O157 in ground beef
• Campylobacter in poultry
• Listeria monocytogenes in processed meats
• Little successful control of
• Multiply-resistant Salmonella (dairy reservoirs,
  ground beef)
• Produce-related problems tomatoes, lettuce,
  melons
• Vibrio ssp (raw oysters)
• Norovirus salads, oysters

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• Antibioticresistant salmonellosis has emerged as
  an important problem

• Two types are of particular concern
• Salmonella Typhimurium (The most common
  serotype)
• Salmonella Newport (Third most common
  serotype)
• Some strains are resistant to many antibiotic
  drugs
• Those strains represent 11 of all human
  salmonellosis (145,000 foodborne infections per
  year)
• Cause more severe and longer illnesses than
  non-resistant strains, and can complicate
  treatment for other infections
• Both have dairy cattle (and other) reservoirs and
  are transmitted through ground beef

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Multidrug-resistant Salmonella Newport(S.
Newport MDR Amp C)

• First appeared in 1999
• Causing epidemic disease in cattle as well as
  humans
• Extremely resistant
• Resistant to nine agents, often more
• Ampicillin, TMP/SXT, ceftriaxone
• Risk factor ground beef, raw milk, taking an
  antibiotic
• Risk factors on farm (Anecdotal)
• Housing newborn calves with ill animals
• Feeding calves raw milk from ill animals
• Animals getting antibiotics for other reasons are
  at risk

State and CDC investigators on a New England
dairy farm where 6 cattle had died,and children
in a day care had become infected
Gupta. J Infect Dis 1881707 2003
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Menu of prevention steps for multi-drug resistant
Salmonella in beef

• Consumer education
• Do not taste raw beef while preparing
• Pathogen reduction - irradiation of ground beef
• Processing practices - review HACCP plans
• Increase focus on multi-drug resistant Salmonella
  as a specific problem
• Which animals likely to carry these pathogens?
• Alternatives to raw ground beef for those
  animals?
• Reduce infections among cattle
• Isolation of sick animals
• Review culling, transport process

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Foodborne outbreaks related to fresh produce,
1973-1997
Sivapalasingam J Food Protection 67 2342-53,
2004
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2004 A sample of produce-associated outbreaks

• Three Salmonella outbreaks from fresh Roma
  tomatoes
• Largest outbreak gt350 cases of S. Javiana
  infection among patrons of a deli chain in
  Northeast
• Salmonella Enteritidis from raw almonds
• 44 cases, almond recall, all almonds to be
  pasteurized in this years harvest
• Airline shigellosis in Hawaii
• 41 cases on 9 flights. Salads with shredded
  carrots
• Cyclospora 96 cases in PA linked to snow peas
  from Guatemala
• E. coli O157NM 3 cases in GA linked to alfalfa
  sprouts from Australian seeds

(Preliminary information)
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The specific challenges of produce-related
foodborne disease

• Often eaten uncooked
• Not easy to wash pathogens off
• Contamination may be introduced at the farm
• Bacteria may enter the internal tissues
• Good Agricultural Practices now being promoted
  are based on common sense
• Do we know enough to prevent contamination from
  occurring?

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How can Salmonella enter an intact tomato?

• Put Salmonella on the tomato flower
• Put Salmonella in the irrigation water
• Dunk a warm tomato into cold water with
  Salmonella
• Bottom line The environment that animals and
  plants live in matters

Guo Appl Env Microbiol 67 4760, 2001 Guo Appl
Env Microbiol 68 3139, 2002 Bartz
Phytopathology 71515 1981
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Norovirus what we do not know can hurt us

• Estimated 9,000,000 cases and 125 deaths annually
• Human reservoir, in feces and vomitus
• Most is direct person-to-person (via hands?)
• Foodborne Salads, sandwiches, shellfish
• Unanswered questions
• How to easily diagnose?
• How long do people shed infectious virus?
• How long will virus persist on food, in water?
• How to inactivate virus on hands, food, water,
  surfaces?

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FoodNet trends 1996-2003
Since 1996, no significant decreases in
Infections with Vibrio 116 Shigella
-9 Listeria -21
1996 1997 1998 1999 2000 2001
2002 2003Year

MMWR 53338-343, 2004
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Foodborne Vibrio infections in the United States

• An estimated 5,200 cases and 30 deaths annually
  (1997)
• V. parahaemolyticus, V. vulnificus
• Underlying liver disease, immunocompromise
• Associated with eating raw shellfish from warm
  waters
• Shellfish sanitation control programs do not work
  for Vibrio
• Control strategy to date - Educate the consumer
• Effective pressure treatment available

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3) Food safety is a global problem

• Imports
• Green onions - Hepatitis A from Mexico
• Mangoes - Salmonella from Brazil
• Queso fresco - Listeria monocytogenes from Mexico
• Snow peas - Cyclospora from Guatemala
• Alfalfa sprouts - E. coli O157NM from Australia
• Exports
• Japan Ground beef - E. coli O157H7 from U.S.
• Canada Almonds - Salmonella Enteritidis from
  U.S.

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Specific challenges in international foodborne
disease

• Responding to international outbreaks requires
  multi-disciplinary collaboration
• Many countries are now where we were 75 years
  ago
• Improving basic sanitation and hygiene in
  exporting countries is in our own interest
• Improving the public health surveillance and food
  safety in exporting countries is integral to
  general development
• Collaborative WHO programs a venue to help

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4) The threat of intentional contamination A
typology of trouble

• Bioterror and biowarfare
• State-sponsored
• Ideologically driven group sponsored
• Biocrime and biomisdemeanors
• Harm for personal gain or revenge
• Bioignorance and biomisfortune
• Common but non-intentional
• Virtually all foodborne disease falls in this
  category
• A daily concern of public health departments
  everywhere

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Dissemination techniques planned in 83 confirmed
bioterror or biocrime incidents, 1900-1999
Carus 2001 Bioterrorism and biocrimes since 1900
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Range of scenarios for a bioterror attack

• An attack at point of food final preparation
• Detection will be swift even with primitive
  surveillance
• Epidemiological investigation to determine
  pathogen, vehicle
• Investigation and response will start with local
  resources with rapid federal support
• An attack at a central point in food production
• Cases of one specific infection spread across the
  country
• Analogous to the unintentional new scenario
  outbreak
• Detection requires laboratory-based surveillance
• Response requires speedy multi-jurisdictional
  investigation
• The same systems that respond to outbreaks now

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Reinforcing public health surveillance and
investigation

• Increasing resources in state and local health
  departments and in national agencies to
• Identify clusters and outbreaks of illness
• Diagnose the cause of the illness more rapidly
• Investigate to determine the sources and
  contributing factors
• Preparing for large events with unusual pathogens
• Preparing medical system for disaster response
• National stockpile of pharmaceuticals

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Food safety in the United States - some
progress, but much more to do

• Farm-to-table prevention can work
• Surveillance and monitoring linked to action can
  drive prevention
• New pathogens and problems will continue to
  emerge
• The rest of the world is closer than it appears
• Bioterror defense includes a prepared public
  health system