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Dr. Harry Snelson - PEDV - Lessons Learned
The document details a comprehensive discussion on Porcine Epidemic Diarrhea Virus (PEDV) from a conference held on June 19, 2014, outlining its impact on pig farming in the U.S. It highlights the virus's transmission, clinical signs, diagnostics, and epidemiology, noting significant research and biosecurity measures developed to combat its spread. The findings emphasize the association of feeding practices with the virus's introduction and the challenges faced in managing outbreaks.
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Introduction to the conference and discussion on Porcine Epidemic Diarrhea Virus (PEDv) by Dr. Harry Snelson.
PEDv symptoms similar to TGE; timeline of disease discovery including initial PCR results and confirmation of PEDv.
Timeline of PEDv positive case confirmations including cases in Indiana and Iowa, and results from diagnostic laboratories.
Presentation of diagnostic submissions, clinical signs of PEDv, and methods including PCR and serological tests.
Introduction of PEDv to North America; epidemiology studies, risk factors for introduction, including feeding practices. USDA's response to PEDv, development of biosecurity protocols, and funding for research regarding the disease.
Studies on contamination in packing plants and feed as a possible vector for PEDv transmission.
Results from an AASV feedback survey regarding success and failure in managing PEDv among affected herds.
Resources for diagnosis, biosecurity guidelines, and cumulative statistics about PEDv accessions in the U.S.
Insights from the outbreak including communication challenges, biosecurity evaluations, and the newly identified Swine Deltacoronavirus.
Acknowledgment of key contributors to research and management efforts of PEDv, highlighting their roles.
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Dr. Harry Snelson - PEDV - Lessons Learned
- 1. Comprehensive Discussion of PEDv 2014Pork Management Conference June 19, 2014 Dr. Harry Snelson AASV
- 2. Disease Discovery Looks likeTGE… Acts like TGE…. Ain’t TGE
- 3. Sun Mon TuesWeds Thurs Fri Sat 28 29 30 1 2 3 4 5 1st Phone Call 6 1st Indiana – Sow Farm 7 2nd Indiana – Sow 8 Initial TGE PCR neg 9 IHC results neg – call vdl 10 EM pos for corona 11 12 13 14 15 16 NVSL confirms PEDV 17 USDA annou nes 18 19 20 21 22 23 24 25
- 4. Sun Mon TuesWeds Thurs Fri Sat 28 29 30 1 May 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 4 cases known (3 in IA, 1 in IN) 18 19 20 21 22 23 24 25 26 27 28 29 30 31 1
- 5. Veterinary Diagnostic Laboratory IowaState UniversityOutcome of retrospective testing & on-boarding PEDV PCR SUNDAY MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY (TOTALS) 15 APRIL 16 OH – GF 17 18 19 20 1 GF 21 22 23 24 25 26 IN – GF 27 1 GF 28 29 IA (W. Central) – SOW 30 IA (NE) – SOW OH – GF IA – GF 1 MAY IA – GF 2 IA – GF 3 IA – GF 4 4 GF 2 SOW 5 6 IA (NW) – SOW 7 IA – GF IA – GF 8 IN – SOW MN – SOW IA – GF 9 IA – GF IA – GF IA – GF 10 CO (Eastern) – SOW IA – GF IN – ?? IN – ?? PA – ?? 11 7 GF 4 SOW 3 UNKNOWN 12 13 MN – GF 14 CO – SOW MN – GF 15 MN – SOW MN – GF 16 IA – SOW 17 IA – SOW IA – SOW IA – GF 18 4 GF 5 SOW (31 actual cases) 19 20 IA – SOW IN – SOW IN – SOW IA – GF MN – GF MN – GF 21 CO – GF IA – GF IA – GF IA – GF IA – GF IA – GF IA – GF IA – GF IA – GF IA – GF MN – GF OH – GF 22 CO – SOW CO – SOW IA – GF IA – GF IA – GF IA – GF IA – GF IA – GF IA – GF OK – GF 23 IA – SOW IA – SOW GF OH MN – ?? 24 IA – GF IA – GF IA – GF IA – GF IA – GF CO – GF CO – GF MN – GF MN – GF MO – GF MN – ?? 25 34 GF 7 SOW 2 UNKNOWN
- 6. Veterinary Diagnostic Laboratory IowaState University PEDV Positive Cases Ascertained from Multiple VDLs Week Received @ VDL Total Number of PEDv Positive Diagnostic Case Submissions (Premises) via PCR or IHC Farm Type CO IA IL IN KS MI MN MO NC NY OH OK PA SD ? Sow Growing Pig ? 4/15/2013 (1), 2 0 1 1 4/22/2013 (1), 1 0 1 1 4/29/2013 (6), 9 2 4 5 1 5/6/2013 (14) , 17 4 7 3 1 8 3 1 1 5/13/2013 (9), 10 5 3 1 1 4 4 5/20/2013 (43), 44 7 33 3 5 25 2 7 1 2 1 Total (74), 83 18 49 7 7 42 6 12 1 11 1 1 * for the weeks prior to 6-17-13, laboratories were able to provide diagnostic case submissions and number of premises testing positive for PEDv. Starting 6-17-13, the data are limited to ONLY diagnostic case submission numbers (aka Swine Accessions)
- 7. Clinical Signs • Clinicallyindistinguishable from TGE – Alpha coronavirus – Fecal-oral pathogen – Profuse diarrhea and vomiting – High mortality rates in neonatal pigs – High morbidity, lower mortality as pigs age • Not zoonotic, not a food safety concern
- 8. Diagnostics • PCR –ready quickly • Serology – IFA – ELISA • No VI – virus is difficult to grow • Bioassay to prove infectivity/viability – Time consuming – Expensive – Lacks sensitivity
- 12. 0% 0% 25% 70% 95% 100% 0% 20% 40% 60% 80% 100% 120% Week 1Week 2 Week 3 Week 4 Week 5 Week 6
- 13. PED virus • Newto North America • In Europe in 1970’s • Current virus present in Asia – U.S. virus 99+ % similar to 2012 isolate from Anhui Province in China • U.S. swine herd naïve, 100% susceptible • No vaccine • Easily transmitted
- 14. Response • USDA designatedPED a “transboundary” disease – Not reportable – Non-regulatory – Production disease like PRRS or PCV – Turned the response over to the swine industry • NPB, NPPC and AASV coordinated effort with USDA to understand the epidemiology and develop a response strategy • Transmitted via contaminated manure • Concentrated on elevating biosecurity
- 15. AASV Response • Collaborationwith producer groups, state/federal/international animal health officials • Outreach/education of veterinary members – Meeting at WPX – Website updated weekly – Collaborate with NPB on research efforts and educational outreach to producers • Epidemiology efforts – Initial introduction survey – RRT participation
- 16. Veterinary Survey • Concern:How did this virus come into the U.S.? • Objective: Identify any risk factors potentially associated with the introduction of the PEDv into the U.S. swine herd • Survey designed by AASV, NPB, NPPC & USDA-CEAH • Administered by practitioners, data transferred to CEAH via link designed by FAZD at Texas A&M • Data analyzed by CEAH • Questionnaire examined > 100 variables • 25 case herds, 18 matched control herds
- 17. Survey Results • Onlyseven variables were considered significantly likely to have some association with the introduction of PEDv • These seven risk factors were associated with the process of feeding the animals. • Did not implicate any specific finished feed, feed ingredient, feed manufacturer or ingredient supplier.
- 18. Epidemiology – ObservationalStudy Question topic Type of Variable Odds Ratio p value Interpretation How many pelleted rations were fed to sows during the last 90 days Continuous 0.45 0.001 When the number of pelleted rations fed to sows goes up by 1, the odds of being a case goes down 55%. Origin of sow feed used in the last 90 days Categorical 2.33 0.002 When sow feed was custom mixed off farm compared to being purchased complete, the odds of being a case goes up 2.3X. What grain was mixed with in sow feed in the past 90 days. Categorical 0.44 0.002 When grain was mixed with an amino acid source, salt, calcium, phosphorus and a premix in sow feed compared to only an amino acid source and a base mix, the odds of being a case goes down 56% How many meal/mash rations were fed to nursery pigs during the last 90 days Continuous 1.65 0.05 When the number of meal/ mash rations fed to nursery pigs goes up by 1, the odds of being a case goes up 65%. How many meal/mash rations were fed to finishers during the last 90 days Continuous 1.51 0.004 When the number of meal/ mash rations fed to finishing pigs goes up by 1, the odds of being a case goes up 51%. Total number of rations fed to finishers during the last 90 days Continuous 1.36 0.04 When the total number of rations fed to finishing pigs goes up by 1, the odds of being a case goes up 36%. What grain was mixed with in finisher feed in the past 90 days. Categorical 0.50 <0.001 When grain was mixed with a supplement in finisher feed compared to with an amino acid source and a base mix, the odds of being a case goes down 50% Contents of premix in the most recent finisher diet Categorical 3.50 0.02 When vitamin and trace mineral premix was in the same premix in the most recent finisher diet the odds of being a case goes up 3.5X.
- 19. Response • Development of3 working groups – Biocontainment • How to limit spread off an infected premises – Biosecurity Transport • Review, modify, recommend biosecurity plans for transport, shows/exhibitions, producers – Packing Plant • Recommend biosecurity principles for packing plants, buying stations, etc • These working groups have developed a number of guides targeting biosecurity published on NPB website
- 20. Research • Pork Board-- $800,000 for PEDv research – Rapid response to research call – Research objectives • Diagnosis • Pathogenesis • Environmental stability • Epidemiology • surveillance – Shortened timeline • 13 days to identify and initiate research projects • Progress updates every two weeks • Six month deadline
- 21. Research • NPB, NPPCand AASV funded a study by Dr. Jim Lowe to look at transmission in harvest plant lairage.
- 22. Lairage Study • Trailersdo become contaminated at packing plants due in part to movement of drivers • The more contact that occurs, the higher the rate of contamination
- 23. One positive trailerin means 1.7 positive trailers at exit Plant Contaminated at entry Contaminated at Plant Contamination Ratio A 2.25% 8.05% 3.58 B 7.00% 4.30% 0.61 C 10.84% 10.81% 1.00 D 2.00% 0.00% 0.00 E 14.56% 3.08% 0.62 G 3.00% 1.03% 0.34 All 5.98% 4.31% 0.72 Courtesy Dr. Jim Lowe
- 24. Research • Dr. MatthewTurner surveyed cull sow buying stations in NC – Minimal biosecurity in place – Virus present, likely transmission occurring – Willingness on the part of the managers to make changes
- 25. Future research focusfor PED • Funding: – NPB - $650,000 – AFIA - $100,000 – Genome Alberta - $500,000 – NGFA - $60,000 • Formation and duration of immunity after infection; What level of immunity is needed for full protection? • Can immunity be overwhelmed? • Continued development and implementation of surveillance strategies for PED • Evaluate strategies for trailer disinfection
- 26. Feed as apossible vector • AASV survey identified feed as likely associated with the introduction • Feed has anecdotally been associated with outbreaks • Numerous bioassays on suspect feed and ingredients have been unable to confirm feed as a source
- 27. Feed Testing May-June, 2013:NVSL tested feed, mineral and vitamin premixes and dried plasma samples. Laboratory testing results (PCR) were negative except for dried plasma products. June, 2013: NVSL conducted a bioassay using a vitamin premix and plasma. The bioassay pigs did not show evidence of infection through testing of the feces and serology. July, 2013: NVSL conducted a bioassay using dried plasma that was obtained from the blender. The bioassay pigs did not show evidence of infection through testing of the feces and serology. Feb., 2014: NVSL tested dried plasma from the manufacturer. The samples were positive utilizing the real time PCR assay, and confirmatory testing is being conducted utilizing the nested PCR. March, 2014: The bioassay for the last group of plasma samples is currently on test.
- 28. Feed as apossible vector • Dr. Scott Dee – has been able to transmit PEDv via feed to naïve pigs • Canada achieved a positive bioassay using spray dried porcine blood plasma but not feed pellets
- 29.
- 30. Feedback Survey • Askedvets that have attempted feedback to respond • Approx. 83 herds represented • 50/50 success vs failure – Success = no “re-break” following feedback – Failure = clinical signs never went away or came back following feedback.
- 34. % Sows with diarrhea %Anorexic sows % IFA + % ELISA + Feedback Success/Failure 65 100 100 S 100 95 100 F 80 40 95 F 100 100 100 F 90 95 86 63 F 70 90 100 F 80 90 80 F 30 30 100 S 50 90 100 F 50 90 100 F 50 80 100 F 35 35 92.5 99 F 30 85 100 100 F 95 70 98 F 35 35 100 S 50 40 100 S 75 100 98 S
- 35.
- 36. • Lab diagnosisneeded for determining site status • Managing biosecurity or biocontainment • Specifics of specimen collection • Feces • Oral fluids 36 Guidelines for Diagnosis of PED Virus
- 37.
- 38.
- 39. Current Status as of5/10/14 Test Results Cumulative PEDv Positive Accessions 6,617 Total Accessions Tested 18,326 Percent PED Positive Accessions 36.1% Number of States Reporting Positive Accessions 29* Courtesy of NAHLN
- 40.
- 42. Canadian Experience • January23 – PEDv confirmed in Ontario • February – CFIA announces PCR positive feed – Positive bioassay with U.S. origin porcine blood plasma – Negative feed bioassay • Has since spread to multiple farms in Ontario and one each in Quebec, Manitoba, and PEI
- 43. What We’ve Learned •Although similar to TGE, PEDv is a different bug – More active in warmer environments – More difficult to control in a sow herd – Clinical picture can be more severe – Apparently no cross protection with TGE or PRCV – Huge amounts of virus are present • Holes in our defense layers – obviously exist but hard to identify – Biosecurity at all levels should be evaluated – Particular emphasis on transport, packing plants
- 44. What We’ve Learned •VDLs responded quickly but challenges with ability to communicate effectively – Tools exist today to facilitate this communication • FAZD has done an excellent job working with industry to facilitate the transfer of information – VDLs and NAHLN have stepped up to try to provide weekly data on new cases but… • Without PINs the data is suspect • Current mechanism is too labor intensive and archaic
- 45. What We’ve Learned •The use and ability to capture PINs would significantly improve data sharing • Challenges exist with defining roles government and industry with transboundary diseases • We are seeing “rebreaks” in 30 – 40% of herds • Swine Deltacoronavirus introduction???
- 46. Swine Deltacoronavirus • Clinicallylooks like TGE/PED but tests negative – Differential PCR available • 1st seen in Hong Kong in 2012 • Identified in Ohio in February • Identified in Canada in March
- 47. Acknowledgements • Dr. MattAckerman – Swine Vet Services • Dr. Rodger Main – ISU VDL • Dr. Brian McCluskey – USDA CEAH • Dr. Paul Sundberg -- NPB