Published on October 31, 2014
What PEDv Taught Us About Biosecurity? - Dr. Peter Davies, University of Minnesota, from the 2014 Allen D. Leman Swine Conference, September 15-16, 2014, St. Paul, Minnesota, USA.
More presentations at http://www.swinecast.com/2014-leman-swine-conference-material
1. What has PEDv taught us about biosecurity? Peter Davies BVSc, PhD Department of Veterinary Population Medicine University of Minnesota, College of Veterinary Medicine, St. Paul, MN, USA
2. Bayesian Thinking • Thomas Bayes – theologian/mathematician • Conditional probability Prior probability (belief/opinion) • Bayesian statistics New Information Revised probability (belief/opinion)
3. Bayesian Thinking What we know, think or believe about biosecurity PEDV experiences What we now know, think or believe about biosecurity
4. What is Biosecurity? (FAO/OIE/World Bank, 2008) • Protection of health through avoidance of disease • Implementation of measures that reduce the risk of the introduction and spread of disease agents • Requires the adoption of a set of attitudes and behaviors by people to reduce risk in all activities
5. Biosecurity Principles in Swine Production • Prevent introduction of disease to a farm — bio-exclusion or “external biosecurity” • Prevent transmission within a farm ― biocontainment or “internal biosecurity”
6. Biosecurity: A science or an art? • Hard to research – use ‘principles’ • What might happen? • What can happen? • What does happen, and how often? • Low risks borne widely = big problem – Car accidents, Foodborne disease, Lightning strike – Pathogen introduction to a country/farm • Difficult to ‘know’ sources of entry
7. Biosecurity: A science or an art? • Opinion >>> evidence • Small amount or research – Contrived conditions – Lack of replication • ‘Normal standards’ – Cost effectiveness – Compromise – Compliance
8. Farm Processes Waste Garbage Reclaim Semen Boars Gilts Breeding Stock Commercial pigs Air Water Feed People Supplies Equipment Pests Farm Inputs and Outputs
9. Controlled access National • Animals • Products • Inputs – Vaccines – Feed ingredients • Trade = risk Farm • Animals • People • Inputs • Fomites, transport • Environment (air,..)
10. Successes: exclusion from herds/regions/countries • Sarcoptic mange, lice • Brucellosis, Pseudorabies • ‘Exotic’ Diseases (e.g. FMD, hog cholera) • Atrophic rhinitis • APP • Swine dysentery? • TGE?
11. Less success • Struggles – high risk of recurrence – PRRS – Influenza – Mycoplasma • “Emerging” diseases – ASF – PEDv
12. What determines success • Characteristics of agent/disease – Routes of exit and transmission – Host range and survival outside the hosts – Infectivity (ID50) • Characteristics of the host – Immunity; infectious period • Characteristics of the environment – Area density; Animal density; hygiene – Biosecurity measures and management
13. What we know about biosecurity • Important • Expensive • Can be annoying • Imperfect • Optimize cost vs. rate of failure – Air filtration, transport biosecurity – Cost of outbreak (boar stud vs. breeding vs. WTF) – Law of diminishing returns
14. What we know about biosecurity • Need clearly described procedures • People need to know the procedures • Compliance is key – Biosecurity culture – ‘Ownership’ and understanding the why • Zero risk does not exist
15. What has PEDv made us ask about biosecurity? • How ‘leaky’ is national biosecurity? – How many new viruses (1…x) • Point source failure vs. systematic deficiencies? • What was the source(s)/failure(s)? • When was the failure? • What needs to be changed?
16. What has PEDv taught us about biosecurity? • ‘High’ standards (PRRS driven) did not prevent epidemic • PEDv ≠TGEV – Current standards OK for TGE – High virus production, low infectivity – Totally naïve population – Immune response appears different • Relative lack of knowledge
17. Agent Concentration Structural characteristics Strain characteristics Aggregation in matrix Environmental conditions Temperature Relative Humidity Water activity pH Organic matter UV light exposure Matrix Feces Water Feed Fomites STABILITY OF THE AGENT OUTSIDE THE HOST
18. Big questions • Industry on wheels – accepted risk! • Role of feed – How important is/was it? – Is PEDv uniquely adapted to feedborne route? – Have we ignored feedborne transmission for other pathogens? • Airborne transmission? • Precautionary vs. science based decisions
19. Best practices
20. Summary • PEDv taught us nothing about biosecurity • It changed the equation nationally – does the system have to change? • It changed the equation nationally – Shift in the cost/benefit of biosecurity investment • Refinement requires real knowledge