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

Salmonella and E coli O157:H7 in Livestock at Agricultural Fairs. Thomas E. Wittum, PhD Veterinary Preventive Medicine The Ohio State University. Salmonella spp. Multiple host species Fecal-oral transmission Important zoonotic food-borne pathogen Can persist in the environment

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

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  1. Salmonella and E coli O157:H7 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 O157:H7 • 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 O157:H7 • 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 O157:H7 • 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 O157:H7 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 O157:H7 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 O157:H7 prevalence in livestock on display at US agricultural fairs

  15. Sampling • County fairs (n=29) • 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 (n=3) • 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 O157:H7 • 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. Beef cattle 4.7% Dairy cattle 4.7% Swine 39.3% Sheep 5.2% Goats 4.9% Other livestock 4.6% Salmonella fecal prevalence in fair livestock

  19. Beef cattle 13.8% Dairy cattle 5.9% Swine 3.6% Sheep 5.2% Goats 2.8% Other livestock 0% 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 O157:H7 • 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 O157:H7 • 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. 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

  24. 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?)

  25. Conclusions E coli O157:H7 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?)

  26. 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

  27. 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

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