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 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 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 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 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 Results –E. coli O157 Factors associated with positive pens OR –Short time in feedlot(<20 days)3.39 –Barley feeding2.75 –Light entry weights (<700)1.85 –Steers3.03 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/ 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

Pathogens in Feedlots – 1999/2000

Results –E. coli O % of feedlots 1+ positive samples 11% (1,148/10,415) of samples positive –Early13.9% –Random10.6% –Late 8.6% Risk factor evaluation underway

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 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 cows5.8 –Southern region5.7 –Use of recycled flush water3.5 –Brewer’s products fed3.4 Kabagambe et al. Prev Vet Med 43:

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

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

Dairy 1996 Factors associated with dairy operations positive for E. coli O157 OR –Samples collected after May 17.7 –Flush alleyways with water8.0 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 layer houses – environmental samples –Manure –Egg belts –Elevators –Walkways 129 layer houses – rodents collected Laboratory evaluation –Salmonella enterica serotype Enteritidis

Layers % 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

Layers

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 Herd38.2%34.7% Sample6.0%6.6%

Salmonella serotypes Swine Derby 2.Agona 3.Typhimurium cop 4.Brandenberg 5.Mbandaka 6.Typhimurium 7.Heidelberg 8.Anatum 9.Enteritids BA 10.Worthington Swine Derby 2.Agona 3.Typhimurium cop 4.Heidelberg 5.Brandenberg 6.Typhimurium 7.Worthington 8.Anatum 9.Infantis 10.Tennessee

Swine – 1995 Salmonella FactorLevelOR(95% CI) Mix on farmYes.4 (.2 -.9) AO (never)Some, most, all2.5 (1.1 – 5.9) Resp Culls (0) (.1 – 1.3) >.25.2 (.1 -.8) Pen Sex (mixed)Single only2.8 (1.0 – 7.8) Both types5.4 (1.8 – 16.3) Region (SE)North.2 (.1 -.6) Midwest.2 (.1 -.7) Meal (Yes)No26.4 (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 nahms.aphis.usda.gov