# Presentation: 728469

## Pathogen Reduction Dialogue Panel 1May 6, 2002Food Safety Pathogens on the Farm

- David A. Dargatz DVM PhD
- USDA:APHIS Centers for Epidemiology and Animal Health
- Ft. Collins, CO

## Summary of Results from NAHMS Studies

- NAHMS – National Animal Health Monitoring System
- Program of USDA Animal and Plant Health Inspection Service (APHIS)
- Program Goal: Provide information on animal health of livestock and poultry throughout the U.S.
- Approach to Pathogens
- Estimate prevalence
- Evaluate risk factors
- Primary focus – *Salmonella* and *E. coli* O157

## Production Systems

- Feedlot cattle (1994 and 1999)
- Dairy (1996)
- Layers (1999)
- Swine (1995 and 2000)

## Pathogens in Feedlots - 1994

- 100 feedlots in 13 states
- Samples collected from Oct – Dec
- Laboratory evaluation
*Salmonella *
- 2 pens of cattle
- culture, serotype
*E. coli* O157
- 4 pens of cattle
- historical culture methods

## Pathogens in Feedlots - 1994

- Results
*Salmonella*
- 38% of feedlots with 1+ positive samples
- 5.5% (273/4,977) of samples positive
- Most common serotypes (65% of isolates)
- S. Anatum
- S. Montevideo
- S. Muenster
- S. Kentucky
- S. Newington

- Fedorka-Cray et al. J. Food Protection 61:525

## Pathogens in Feedlots - 1994

- Results
*Salmonella*
- Factors associated with positive pens
- Tallow
- Whole cottonseed or cotton seed hulls
- Factors not associated with positive pens
- Region
- Operation size
- Use of sprinklers
- Time on feed
- Type of cattle
- Cattle density
- Other feed ingredients

- Losinger et al. Prev. Vet. Med. 31:231

## Pathogens in Feedlots - 1994

- Results
*E. coli* O157
- 63% of feedlots 1+ positive samples
- 1.8% (210/11,881) of samples positive

- Hancock et al. J. Food Protection 60:462

## Pathogens in Feedlots - 1994

- Results
*E. coli* O157
- Factors associated with positive pens
- 						OR
- Short time in feedlot	(<20 days)	3.39
- Barley feeding			2.75
- Light entry weights (<700)		1.85
- Steers				3.03
- Factors not associated with positive pens
- Region
- Operation size
- Animal density
- Ionophore use
- Other feed ingredients

- Dargatz et al. J. Food Protection 60:466

## Pathogens in Feedlots – 1999/2000

- 73 feedlots in 11 states
- Samples collected from Oct 1999 – Sept 2000
- Each feedlot visited twice
- Laboratory evaluation
*Salmonella*
- 3 pens
- Culture, serotype
*E. coli* O157
- 3 pens
- immunomagnetic bead separation

## Pathogens in Feedlots – 1999/2000

- Results
*Salmonella*
- 51% of feedlots with 1+ positive samples
- 6.3% (654/10,417) of samples positive
- Most common serotypes (72% of isolates)
- S. Anatum*
- S. Montevideo*
- S. Reading
- S. Newport
- S. Kentucky*
- Risk factor evaluation underway

- http://nahms.aphis.usda.gov/Beef_Feedlot/99sal.pdf

## Pathogens in Feedlots – 1999/2000

## Pathogens in Feedlots – 1999/2000

- Results
*E. coli* O157
- 100% of feedlots 1+ positive samples
- 11% (1,148/10,415) of samples positive
- Early	13.9%
- Random	10.6%
- Late	  8.6%
- Risk factor evaluation underway

- http://nahms.aphis.usda.gov/Beef_Feedlot/coli.PDF

## Pathogens in Feedlots – 1999/2000

## Dairy 1996

- Operations in 19 states
- 91 dairies
- 97 markets
- Samples collected from Feb – Jul
- Milk cows (n=3,640)
- Cull cows on farm (n=668)
- Cull cows in markets (n=2,287)
- Laboratory evaluation
*Salmonella *– culture, serotype
*E. coli *O157 – historical culture methods

## Dairy 1996 – Salmonella

- Overall cow-level prevalence
- Milk cows 5.4%
- Expected culls 18.1%
- Culls at markets 14.9%
- Most common serotypes (63.2%)
*S. *Montevideo
*S.* Cerro
*S. *Kentucky
*S. *Menhaden
*S. *Anatum
*S. *Meleagridis

- Wells et al. J. Food Protection 64:3

## Dairy 1996 - Salmonella

- 21.1% of operations had milk cows shedding
- 25.9% of operations had expected culls shedding
*Salmonella* shedding on dairies related to
- 								OR
- Larger herd size – 100 or more cows	5.8
- Southern region				5.7
- Use of recycled flush water			3.5
- Brewer’s products fed			3.4

- Kabagambe et al. Prev Vet Med 43:177-194

## Percent of Samples with VT E. coli O157  NAHMS Dairy ‘96 Study

- Percent of Samples with VT *E. coli* O157  NAHMS Dairy ‘96 Study

- http://nahms.aphis.usda.gov/Dairy_Cattle/ecosalm98.htm

## Percent of Operations with VT E. coli O157  NAHMS Dairy ‘96 Study

- Percent of Operations with VT *E. coli* O157  NAHMS Dairy ‘96 Study

- http://nahms.aphis.usda.gov/Dairy_Cattle/ecosalm98.htm

## Dairy 1996

- Factors associated with dairy operations positive for *E. coli *O157
- 								OR
- Samples collected after May 1	7.7
- Flush alleyways with water		8.0

- Garber et al., J Food Protection 62:307

## Dairy 1996

- Factors not associated with shedding of *E. coli *O157 on dairy farms
- Manure handling practices
- Chlorination of water tanks
- Grazing
- Housing type
- Diet components (protein, fat, byproducts, probiotics, alfalfa)

- Garber et al., J Food Protection 62:307

## Layers - 1999

- 200 layer houses – environmental samples
- Manure
- Egg belts
- Elevators
- Walkways
- 129 layer houses – rodents collected
- Laboratory evaluation
*Salmonella enterica* serotype Enteritidis

## Layers - 1999

- 7.1% of layer houses positive
- 3.7% of house mice were positive
- Factors associated with positive houses
- Flocks < 60 weeks
- Not cleaning feeders or hoppers between flocks
- Higher number of rodents

- http://nahms.aphis.usda.gov/Poultry/lay99SEhi.htm

## Layers - 1999

- http://nahms.aphis.usda.gov/Poultry/lay99SEhi.htm

## Swine – 1995 and 2000

- Swine 1995
- 152 operations in 16 states
- At least 300 grower/finishers
- Up to 50 samples per site from late finishers
- Total of 6655 samples
- Swine 2000
- 124 operations from 17 states
- At least 100 head inventory
- Up to 50 samples per site from late finishers
- Total of 5509 samples

## Swine – 1995 and 2000

| Salmonella
Prevalence | 
1995 | 
2000 |
| --- | --- | --- |
| Herd | 38.2% | 34.7% |
| Sample | 6.0% | 6.6% |

**Notes:**
2000:
43 sites out of 124 = 34.7%
363 samples out of 5509 = 6.6%

1995:
58 out of 152 = 38.2%
398 out of 6655 = 6.0%

## Salmonella serotypes

_**Swine 1995**_
- Derby
- Agona
- Typhimurium cop
- Brandenberg
- Mbandaka
- Typhimurium
- Heidelberg
- Anatum
- Enteritids BA
- Worthington

_**Swine 2000**_
- Derby
- Agona
- Typhimurium cop
- Heidelberg
- Brandenberg
- Typhimurium
- Worthington
- Anatum
- Infantis
- Tennessee

**Notes:**
1995 – top 10 accounted for 85% of all isolates
2000 – top 10 accounted for 81.3% of all isolates

## Swine – 1995

*Salmonella*
- _Factor__	__	__Level__	__	__	__OR__	__(95% CI)_
- Mix on farm	Yes			.4 	(.2 -.9)
- AO (never)	Some, most, all	2.5 	(1.1 – 5.9)
- Resp Culls (0)	.01 - .25		.3 	(.1 – 1.3)
- 				> .25			.2 	(.1 - .8)
- Pen Sex (mixed)	Single only		2.8 	(1.0 – 7.8)
- 				Both types		5.4 	(1.8 – 16.3)
- Region (SE)	North			.2 	(.1 - .6)
- 				Midwest		.2 	(.1 - .7)
- Meal (Yes)	No			26.4 	(2.8 – 249)

## Swine 1995 – E. coli O157

*E coli* O157:H7
- Tested a subset (4,229) of Salmonella fecal samples
- All were negative

## Pathogens on the Farm - Conclusions

- Widely distributed geographically and by operation type
- Region generally not a factor
- Similar prevalence for *Salmonella *across operation types
- Mostly present in low numbers or low prevalence
- Inconsistent risk factors identified across epidemiologic studies
- Data from large epidemiologic studies should be used to generate hypotheses to be evaluated in more controlled experiments
- More research is needed to evaluate interventions (biosecurity and active measures)

## More Information Available

**USDA:Centers for Epidemiology and Animal Health**
**555. S. Howes**
**Ft. Collins, CO 80521**
**970 490-8000**
**NAHMSWEB@aphis.usda.gov**
**nahms.aphis.usda.gov**