This document discusses the costs and importance of controlling Salmonella in pork production. Salmonella is a major public health concern, causing over 100,000 cases annually in the US. Pre-harvest risks on farms include transmission from sows to piglets, contaminated feed ingredients, and contaminated facilities. Controlling Salmonella on farms can provide economic benefits by reducing prevalence. However, conventional control methods like heavy metals and antimicrobials carry risks of increasing antimicrobial resistance. Alternative control methods like vaccination have shown benefits in field tests, improving average daily gain and feed conversion for pigs. Further research is needed on new bivalent vaccines to enhance Salmonella control.

1. Cost & importance of
Salmonella
in the production of Pork

2. Scope of the problem
• Pigs
– Salmonella enterica group
• Pre 1995 – Choleraesuis (C1) most prevalent
• Today – Typhimurium (B, aka 0:4)
• Iowa State University survey
• People (USDA, CDC, Miller)
– Typhimurium #1 public health serovar (0:4, 4/5/12)
• More significant than Campylobacter!
– Estimated >100,000 human cases annually (~11% of 1M/yr)*
• 35% of hospitalizations, 28% of deaths
*FSIS Compliance Guide
CDC National Enteric Disease Surveillance Overview

3. Pre-harvest risk
• Pre-harvest food safety risks of pork
– On farm (Rostangno, Funk, Hurd, Alban, DeBusser)
• Pigs
– Sow to piglet transmission
– Split marketing
• Feed
– Contamination of ingredients
– Cross contamination at plant/transport, in feeder
• Facilities
– Continuous production, fomites

4. Pre-harvest risk
• Pre-harvest food safety risks of pork
– At plant (FSIS, Cray)
– Transport & lairage (Erdman)
• Rapid Extra-intestinal Dissemination
• Contaminated trucks
• Holding pens
– Direct contamination (Hurd)
• Pleural lesions/herd health; more lesions = more tearing/contamination
– Indirect contamination
• Knives, saws, other equipment
– Carcass swabs vs lymph nodes/ground meat
• FSIS transitions (beef first)

5. Economics of control
• Economics of on farm control (Kleibenstein)
– Danish control standards
• Level 3 vs 1 = 5.2 fewer #/sq ft/year
• Level 2 vs 1 = 2.9 fewer #/sq ft/year
– Food safety benefits approximate benefits
• Production benefit will drive implementation unless regulated
• High seroprevalence sites (Baum)
– High prevalence sites (>15% seropositive, or Level 3 farms)
• 4.9#/sq ft/year less pork than low prevalence sites (Level 1)

6. Risks of conventional control
• Heavy metals (Medardus)
– Use of heavy metals, e.g. Zinc, Copper
• Resistance against zinc also selects for antimicrobial resistance
• Amoxicillin/Streptomycin/Tetracycline/Kanamycin
• Serovars Typhimurium & Heidelberg especially susceptible
• Antimicrobials
– On farm use
– Transmission of resistance serovars via feed (Molla)
– Resistance in environmental organisms

7. Benefits of alternate control
• Field results (Case study 1; Baum)
– Vaccinated or non vaccinated high prevalence barns, side by side
comparison
» +0.1 ADG,
» -0.2 F/G advantages for vaccinated pigs
• Field results (Case study 2; Kolb)
– Before/after project
• +0.09 ADG,
• -0.11 F/G
• Vaccine should play a role (Rostangno)
– enhanced control with more complete protection??
– How will Enterisol Salmonella TC perform as a bivalent vaccine?