Pre-Harvest Risk Factors for Salmonella in Pork Production - Dr. Marcos H. Rostagno, Research Animal Scientist/Adjunct Faculty, USDA-ARS / Purdue University, from the 2013 Boehringer Ingelheim Swine Health Seminar, August 16-18, 2013, Wrightsville Beach, NC, USA. More presentations at http://www.swinecast.com/2013-boehringer-ingelheim-carolina-swine-health-seminar

1. Pre-Harvest Risk Factors forPre-Harvest Risk Factors for
SalmonellaSalmonella in Pork Productionin Pork Production
Marcos H. RostagnoMarcos H. Rostagno, DVM, MPVM, PhD, DVM, MPVM, PhD
Research Animal Scientist / Adjunct FacultyResearch Animal Scientist / Adjunct Faculty
USDA-ARS / Purdue UniversityUSDA-ARS / Purdue University
BIVI – NC Swine Health – August/2013

2. @@

3. How important is food safety???How important is food safety???
The world is changing…The world is changing…
……and so is “our world”!and so is “our world”!
Animal ProductionAnimal Production

Food ProductionFood Production

4. Priorities driving consumer food choicesPriorities driving consumer food choices
(Center for Food Integrity, 2012)(Center for Food Integrity, 2012)
SafetySafety
AffordabilityAffordability
NutritionNutrition
(56.87%)(56.87%)
ProductivityProductivity
ProfitabilityProfitability
(8.12%)(8.12%)
EnvironmentEnvironment
WelfareWelfare
(35.01%)(35.01%)

5. Food Security + SafetyFood Security + Safety
Food Safety Issues:Food Safety Issues:
 Chemical hazardsChemical hazards
 Physical hazardsPhysical hazards
 Biological hazardsBiological hazards
. Pathogens. Pathogens
. Antimicrobial Resistance. Antimicrobial Resistance
Quality assurance
Complex challengesComplex challenges
On-farm (pre-harvest) focusOn-farm (pre-harvest) focus
SalmonellaSalmonella

6. How important isHow important is SalmonellaSalmonella??????
How important isHow important is SalmonellaSalmonella in pork???in pork???
??

7. Scallan et al. (2011)

8. According to USDA-ERSAccording to USDA-ERS
$2.3 billion (in 1998 U$)$2.3 billion (in 1998 U$)
Medical costsMedical costs
++
Productivity lossesProductivity losses
Frenzen et al.(1999)
Hoffmann et al.(2012)

9. Incidence of foodborne pathogens in the U.S.
Healthy People 2010
Salmonella (6.8)
Campylobacter (12.3)
E. coli O157 (1.0)
Source: www.cdc.gov/foodnet/data/reports.html

10. SalmonellaSalmonella: a food safety priority for the pork industry!: a food safety priority for the pork industry!
Attribution: Pork productsAttribution: Pork products  5-30% Human salmonellosis5-30% Human salmonellosis
US (6-9%)US (6-9%)
EU (15-25%)EU (15-25%)
Salmonella prevalence + levels in the GIT
(Determinants of the pork safety risk)
Berends et al.(1996):
Infected pig  Slaughter line = 3 - 4x risk of Salmonella-contaminated carcass
Salmonella contamination of pork occurs within abattoirs
(Slaughter and processing line)
Infected pigs (“carriers”)Infected pigs (“carriers”)

11. Positive Salmonella tests in the PR/HACCP verification
testing program from 1998 to 2011
(Market hogs - All sizes)
www.fsis.usda.gov

12. www.fsis.usda.gov

13. From Pig to PorkFrom Pig to Pork
SalmonellaSalmonella Prevalence and Levels in the GI tractPrevalence and Levels in the GI tract
Salmonella
Salmonella contamination risk
contamination risk
FarmFarm TransportTransport LairageLairage Harvest &Harvest &
ProcessingProcessing
??????

14. What do we know aboutWhat do we know about SalmonellaSalmonella
infection in swine???infection in swine???

15.  Transmission: fecal-oral + aerosolsTransmission: fecal-oral + aerosols
 Rapid dissemination throughout the gastrointestinal tract, withRapid dissemination throughout the gastrointestinal tract, with
fecal shedding within only 2 hours post-infectionfecal shedding within only 2 hours post-infection
 Disease is very difficult to reproduce experimentally; interactionDisease is very difficult to reproduce experimentally; interaction
of dose x serovar x immune statusof dose x serovar x immune status
 Contaminated environment with low numbers (10Contaminated environment with low numbers (1022
-10-1033
cfu) ofcfu) of
SalmonellaSalmonella enough to infect exposed pigsenough to infect exposed pigs
 Infected pigs can carry (with no clinical symptoms)Infected pigs can carry (with no clinical symptoms) SalmonellaSalmonella
in the intestinal tract and associated lymph nodes, and excretein the intestinal tract and associated lymph nodes, and excrete
high numbers ofhigh numbers of SalmonellaSalmonella in feces intermittently orin feces intermittently or
continuously for several weeks (serovar x dose x immune status)continuously for several weeks (serovar x dose x immune status)

16. Hurd et al.(2001)
SalmonellaSalmonella rapid infectionrapid infection
in market-age pigsin market-age pigs
Environmental exposure dose:
4.2 x 102
– 2.2 x 104
cfu/g

17. Rostagno et al.(2011)
SalmonellaSalmonella infection in finishing pigsinfection in finishing pigs

18. On-Farm Risk FactorsOn-Farm Risk Factors
A variety of potential risk factors have been investigatedA variety of potential risk factors have been investigated

Conflicting findings/reports are very commonConflicting findings/reports are very common
It’s more complicated than we think!It’s more complicated than we think!

20. Jones & Richardson (2004)

21. Jones & Richardson (2004)
Mash Pellet P value
Enterobacteriaceae counts 4.01 log10 cfu/g 1.97 log10 cfu/g ND
Salmonella frequency 16/178 (9%) 21/451 (4.7%) 0.0375

22. 4.8%4.8%
4.9%4.9%
3.5%3.5%
Torres et al.(2011)

23. Torres et al.(2011)

24. Rajic et al.(2007)

25. Additional On-Farm Risk Factors to Consider:Additional On-Farm Risk Factors to Consider:
 Occurrence of clinical salmonellosisOccurrence of clinical salmonellosis
 Occurrence of other infections/diseasesOccurrence of other infections/diseases
-- PRRSvPRRSv
-- Lawsonia intracellularisLawsonia intracellularis
-- PCV2vPCV2v
-- ParasitesParasites
 Continuous flow x All-in/all-out systemsContinuous flow x All-in/all-out systems
 Nose-to-nose contact between pensNose-to-nose contact between pens
 Number of pig suppliers (or number of sources)Number of pig suppliers (or number of sources)
-- Breeding herd & GrowersBreeding herd & Growers
 Biosecurity + Hygiene and disinfectionBiosecurity + Hygiene and disinfection
-- Facilities & EmployeesFacilities & Employees

26. Gebreyes et al.(2008)
Alternative x Conventional Production SystemsAlternative x Conventional Production Systems

27. From the farm to the abattoir...From the farm to the abattoir...
““Peri-marketing” or “Peri-harvest”Peri-marketing” or “Peri-harvest”
management practicesmanagement practices

On-farmOn-farm
TransportationTransportation
AbattoirAbattoir
??

28. Rostagno et al.(2003)
AbattoirAbattoir
Holding Pens as aHolding Pens as a
Source ofSource of SalmonellaSalmonella

29. Rostagno et al.(2005)

30. SalmonellaSalmonella
SalmonellaSalmonella
SalmonellaSalmonella
SalmonellaSalmonella
SalmonellaSalmonella
SalmonellaSalmonella
SalmonellaSalmonella
SalmonellaSalmonella
SalmonellaSalmonella
SalmonellaSalmonella
SalmonellaSalmonella

31. Lots of potential stressors!Lots of potential stressors!
Lots of potential stressors!Lots of potential stressors!
 Salmonella ???Salmonella ???
Does pre-slaughter stress affect pork safety risk?Does pre-slaughter stress affect pork safety risk?

32. Salmonella entericaSalmonella enterica prevalence:prevalence:
First pull versus close out groups of market pigsFirst pull versus close out groups of market pigs
0
10
20
30
40
50
60
70
80
90
100
Bacteriology Serology
Prevalence(%)
First Pull
Close Out
43/405 (10.6%, 95%C.I. 6.03–15.2%)
vs.
80/405 (19.8%, 95%C.I. 11.3–28.2%)
85/450 (18.9%, 95%C.I. 12.7–25.1%)
vs.
226/450 (50.2%, 95%C.I. 12.7–25.1%)
9.2%
P<0.05
31.3%
P<0.05
Rostagno et al. (2009)

33. Effect of transport and lairageEffect of transport and lairage
onon SalmonellaSalmonella prevalenceprevalence
(Field Study)(Field Study)Prevalence(%)
a,b,c: P<0.05
Rostagno & Richert (2010)

34. Ctr: Control
FW: Feed Withdrawal (12 h)
T: Transport (2 h)
FWT: Feed Withdrawal + Transport
a
b
a
b
a a
a
b
a a a a
IleumIleum CecumCecum RectumRectum
Log10CFU/gofsample
a,b:a,b: PP<0.05<0.05
SalmonellaSalmonella levels in market-weight pigslevels in market-weight pigs
subjected to feed withdrawal and/or transportsubjected to feed withdrawal and/or transport
Rostagno et al. (2012)

35. Effect of stress on the susceptibilityEffect of stress on the susceptibility
of market-age pigs toof market-age pigs to SalmonellaSalmonella
(Transport and/or mixing)(Transport and/or mixing)
Rostagno & Lay (2012)
a
b b,c
c
aaa
b
a,b,c:a,b,c: PP<0.05<0.05 a,b:a,b: PP<0.05<0.05
C = Control
M = Mixing w/ unfamiliar pig (6 h)
T = Transport (1 h)
T+M = Transport + Mixing

36. The effect of stress on microbial populations in the intestinal tract ofThe effect of stress on microbial populations in the intestinal tract of
swine isswine is specific to some bacteriaspecific to some bacteria, and dependent on its, and dependent on its intensity/typeintensity/type,,
and on the portion of the GI tractand on the portion of the GI tract where the bacteria is locatedwhere the bacteria is located..
This is way tooThis is way too
complicated!!!complicated!!!
Pre-slaughter stress increases shedding prevalencePre-slaughter stress increases shedding prevalence
and levels ofand levels of Salmonella entericaSalmonella enterica in market-pigsin market-pigs
Increased risk of carcass contaminationIncreased risk of carcass contamination

Increased pork safety risk !Increased pork safety risk !

37. CumulativeCumulative SalmonellaSalmonella fecal shedding frequencyfecal shedding frequency
at 6 h post-challengeat 6 h post-challenge
41.7%b
25%a,b
0%a
a,b: P<0.05
DDGS xDDGS x SalmonellaSalmonella
Rostagno et al. (unpublished)

38. CumulativeCumulative SalmonellaSalmonella fecal shedding frequencyfecal shedding frequency
at 21 d (3 wks) and 35 d (5 wks) post-challengeat 21 d (3 wks) and 35 d (5 wks) post-challenge
a,b: P<0.05
40%a
25%b
a,b: P<0.05
DDGS xDDGS x SalmonellaSalmonella
80%a
50%b
Rostagno et al. (unpublished)

39. SalmonellaSalmonella ecology and epidemiologyecology and epidemiology
in swine populations is very dynamic!!!in swine populations is very dynamic!!!

40. It changes over time and between cohortsIt changes over time and between cohorts
Longitudinal sampling and testing is required for proper monitoring!Longitudinal sampling and testing is required for proper monitoring!
Rostagno et al.(2012)
Variable PrevalenceVariable Prevalence

41. Bacteriology x SerologyBacteriology x Serology
Rostagno et al.(2012)
Correlation
(Spearman's rho)
between fecal
bacteriologic culture
and serology
prevalence estimates
was moderate (0.59).

42. Investigation of On-FarmInvestigation of On-Farm SalmonellaSalmonella Risk Factors:Risk Factors:
Some Critical Issues to ConsiderSome Critical Issues to Consider
 Differences and Inconsistencies Observed…Differences and Inconsistencies Observed…
-- Sampling Source (farm x abattoir)Sampling Source (farm x abattoir)
-- Sampling Design (size, selection, type)Sampling Design (size, selection, type)
-- Diagnostic Approach (bacteriology x serology)Diagnostic Approach (bacteriology x serology)
-- Diagnostic Method (sensitivity and specificity)Diagnostic Method (sensitivity and specificity)
 Differences Between Production Systems…Differences Between Production Systems…

43. What can we do about it???What can we do about it???

44. SalmonellaSalmonella Control Strategy:Control Strategy:
Pre-harvest x Post-harvestPre-harvest x Post-harvest
Post-harvest interventions seem to be more efficient.Post-harvest interventions seem to be more efficient.
However…However…
Pre-harvest interventions contribute to the effectiveness ofPre-harvest interventions contribute to the effectiveness of
post-harvest interventions!post-harvest interventions!
Pre-harvest interventions:Pre-harvest interventions:
Strict Biosecurity and Hygiene/Disinfection ProgramStrict Biosecurity and Hygiene/Disinfection Program

 Risk of exposure to infection sourcesRisk of exposure to infection sources
 Persistence of the pathogen in the environmentPersistence of the pathogen in the environment
++
Peri-harvest transportation and lairage measuresPeri-harvest transportation and lairage measures
From breeding herd to finishers!From breeding herd to finishers!

45. Targeted InterventionsTargeted Interventions
In-feed or water:In-feed or water:
ProbioticsProbiotics
PrebioticsPrebiotics
Organic acidsOrganic acids
Essential oilsEssential oils
Etc, etc, etc...Etc, etc, etc...
Which one?Which one?
When?When?
ManipulationManipulation
of theof the
gastrointestinalgastrointestinal
microbialmicrobial
ecosystemecosystem
There is no “silver bullet” to controlThere is no “silver bullet” to control SalmonellaSalmonella!!!!!!
It must be done with a program!!!It must be done with a program!!!

48. Concluding Thought...Concluding Thought...
““The Salmonella challenge”The Salmonella challenge”
Everyone has a critical role...Everyone has a critical role...
Producers, processors, retailers, and consumers!Producers, processors, retailers, and consumers!
Everyone must be committed,Everyone must be committed,
or we won’t make progress!!!or we won’t make progress!!!

49.  USDA-ARS-LBRUUSDA-ARS-LBRU
. Scientists. Scientists
Dr. Donald LayDr. Donald Lay
Dr. Susan EicherDr. Susan Eicher
. Gary Nowling. Gary Nowling
. Rita Lockeridge. Rita Lockeridge
. Kim McMunn. Kim McMunn
 Purdue UniversityPurdue University
. Dr. Brian Richert. Dr. Brian Richert
. Dr. Paul Ebner. Dr. Paul Ebner
 Iowa State UniversityIowa State University
. Dr. Scott Hurd. Dr. Scott Hurd
. Dr. James McKean. Dr. James McKean
 Undergraduate & Graduate StudentsUndergraduate & Graduate Students
AcknowledgementsAcknowledgements