Salmonella and E coli O157:H7 in Livestock at Agricultural Fairs

1
Salmonella and E coli O157H7 in Livestock at
Agricultural Fairs

• Thomas E. Wittum, PhD
• Veterinary Preventive Medicine
• The Ohio State University

2
Salmonella spp

• Multiple host species
• Fecal-oral transmission
• Important zoonotic food-borne pathogen
• Can persist in the environment
• Frequently shed by healthy animals
• Ubiquitous in the environment

3
Human illness caused by Salmonella

• Incubation 6-72 hours
• Diarrhea/bloody diarrhea
• Abdominal cramps
• Fever
• Self-limiting except for immunosuppressed

4
Escherichia coli O157H7

• Multiple host species
• Fecal-oral transmission
• Important zoonotic food-borne pathogen
• Can persist in the environment
• Frequently shed by healthy animals
• Seasonality of shedding

5
Human illness caused by O157H7

• Incubation 1-10 days
• Abdominal cramps and diarrhea
• Bloody diarrhea
• Hemolytic uremic syndrome (HUS)
• Antimicrobial therapy is contraindicated

6
Zoonotic transmission

• Primarily food-borne
• Direct animal to human transmission can and does
  occur easily in environments conducive to
  interaction
• Not an efficient mode of transmission
• Some environments provide the opportunity for
  high-level exposure of high-risk individuals
• Animal exhibits
• Agricultural fairs

7
Outbreaks at Animal Exibits

• Salmonella
• 1991 Seattle Pacific Science Center
• 1996 Denver Zoological Gardens
• E coli O157H7
• 2000 Washington petting zoo
• 2000 Pennsylvania petting zoo

8
US Agricultural Fairs

• The 3500 US State Fairs (large, regional)
  County Fairs (small, local) attract 150 million
  visitors annually
• Fairs provide opportunity for direct sometimes
  intimate human contact with livestock, including
  children
• Several European N American human STEC O157
  outbreaks linked w/ visits to farms fairs
  exhibiting livestock

9
Risk for outbreaks at fairs

• Most fairs held in summer or early fall
• warm weather
• Mix urban/suburban children with farm livestock
• Multiple US county fair outbreaks since 1998
• Most US fair outbreaks linked to
• contaminated water supplies
• direct contact w/ ruminants (cattle, sheep,
  goats)
• airborne transmission (dust?) from livestock
  barns

10
E coli O157H7 fair outbreaks

• 1999
• New York, Washington Co Fair 610 (171) Water
• Ontario, Canada Fair 159 (7) Petting zoo
• 2000
• Ohio, Medina Co Fair 39 Water
• 2001
• Wisconsin, Ozaukee Co Fair 56 Animal contact
• Ohio, Lorain Co Fair 40 Show barn
• Ohio, Wyandot Co Fair 20 Hand washing

11
E coli O157H7 fair outbreaks

• 2002
• Oregon, Lane Co Fair 86 Sheep/goat barn
• 2003
• Texas, Fort Bend Co Fair 7 Animal contact
• 2004
• North Carolina State Fair 112 Petting zoo
• 2005
• Florida, multiple fairs/festivals 72 Petting zoo

12
Agricultural Fair Livestock

• Husbandry management very different than
  commercial livestock
• Anti-thesis of factory farming
• Meticulously groomed, cleaned bathed
  before/during fairs
• Typically extremely well-cared for and well-fed
• Exhibitors work to impress judges with the good
  condition of their livestock and hygiene of their
  pens (competitions)
• Usually reared individually or in small groups
• Market weight animals typically sold at end of
  fair
• Often very tame friendly towards people

13
Fairs represent particularly intense episodes of
close contact between large numbers of humans,
farm animals, and food/beverage vendors in the
presence of unregulated water systems Jay
Varma, CDC, Sept 2002
14
Objective

• To estimate fecal Salmonella and E coli O157H7
  prevalence in livestock on display at US
  agricultural fairs

15
Sampling

• County fairs (n29)
• 22 fairs visited in State A (July-Oct 2002)
• 7 fairs visited in State B (July-Aug 2002)
• 25 cattle, 25 pigs, other species flies as
  available
• State Fairs (n3)
• 3 State Fairs A, B, and C visited Aug, Sept,
  Oct, 2002
• 60-70 market breeding beef, swine, dairy
  cattle
• Other species (sheep, goats, flies) as available

16
Sampling

• Bacterial culture
• Availability sampling of individuals
• Fair, owner, animal anonymity required
• All samples cultured for Salmonella spp and E
  coli O157H7
• Other non-O157 STEC

17
Samples Collected

• 2919 freshly ground-deposited livestock feces
• one sample per animal or pen (pigs, sheep, goats)
• 154 fly pools
• 8,000 blow flies, stable flies, house flies
• live trapped or netted from dumpsters, garbage
  cans, wash stations, livestock buildings, etc

18
Salmonella fecal prevalence in fair livestock
19
E coli O157 fecal prevalence in fair livestock
20
Results

• Salmonella spp
• Isolated from livestock at most fairs (96 fair
  prevalence)
• 16.4 prevalence in fly pools
• E coli O157H7
• Isolated from livestock at all 29 county fairs
  all 3 State Fairs (100 fair prevalence)
• 7.1 prevalence in fly pools
• 1 human STEC O157 hemorrhagic colitis case linked
  with visit to one of the sampled county fairs

21
Demonstration Milk Cows

• One cow was shedding E coli O157H7
• Second cow had Salmonella hide contamination
• Contact with hundred of children per day

22
Hand Sanitizing Stations

• 17 located in animal barns at State Fair A
• First check 5/17 usable
• Second check 6/17 usable
• No stations observed at State Fair B

23
(No Transcript)
24
(No Transcript)
25
Follow-up testing

• Fair environmental samples collected prior to
  summer 2003 fair
• Both Salmonella spp and E coli recovered from
  fair environments
• Environmental persistence of isolates

26
Conclusions
Salmonella spp
common at US fairs, esp in swine fecal
prevalence similar to summer prevalence in
commercial livestock present in swine
ruminants frequent in/on pest flies (vector?)
27
Conclusions
E coli O157H7
common at US fairs, esp in cattle fecal
prevalence similar to summer prevalence in
commercial livestock present in swine
ruminants frequent in/on pest flies (vector?)
28
Recommendations ??

• CDC
• Provide information about risk
• Design venue to minimize risk
• Adequate hand-washing facilities
• Prohibit hand-to-mouth activities in animal
  interaction areas
• Heightened precautions for high-risk individuals

29
Additional Possibilities??

• Test animals prior to fair entry
• Limitations of tests
• Disinfection of fair environment
• Nearly impossible to disinfect agricultural
  environment
• Treatment of animals prior to fair entry
• Oral neomycin

30
(No Transcript)