Download - Dr. Harry Snelson - PEDV - Lessons Learned
Comprehensive Discussion of PEDv
2014 Pork Management ConferenceJune 19, 2014
Dr. Harry SnelsonAASV
Disease Discovery
Looks like TGE…
Acts like TGE….
Ain’t TGE
Sun Mon Tues Weds Thurs Fri Sat
28 29 30 1 2 3 4
5 1st
Phone Call
6 1st
Indiana – Sow Farm
7 2ndIndiana – Sow
8InitialTGE PCR neg
9IHC results neg –call vdl
10EM posfor corona
11
12 13 14 15 16 NVSL confirmsPEDV
17USDA announes
18
19 20 21 22 23 24 25
Sun Mon Tues Weds Thurs Fri Sat
28 29 30 1 May
2 3 4
5 6 7 8 9 10 11
12 13 14 15 16 174 cases known(3 in IA, 1 in IN)
18
19 20 21 22 23 24 25
26 27 28 29 30 31 1
Veterinary Diagnostic LaboratoryIowa State UniversityOutcome of retrospective testing & on-boarding PEDV PCR
SUNDAY MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY(TOTALS)
15 APRIL 16OH – GF
17 18 19 201 GF
21 22 23 24 25 26IN – GF
271 GF
28 29IA (W. Central) – SOW
30IA (NE) – SOW OH – GF IA – GF
1 MAYIA – GF
2IA – GF
3IA – GF
44 GF2 SOW
5 6 IA (NW) – SOW
7IA – GF IA – GF
8IN – SOWMN – SOWIA – GF
9IA – GF IA – GFIA – GF
10CO (Eastern) – SOWIA – GF IN – ??IN – ??PA – ??
117 GF 4 SOW3 UNKNOWN
12 13MN – GF
14CO – SOWMN – GF
15MN – SOW MN – GF
16IA – SOW
17IA – SOW IA – SOW IA – GF
184 GF 5 SOW(31 actualcases)
19 20IA – SOW IN – SOW IN – SOW IA – GF MN – GFMN – GF
21CO – GFIA – GF IA – GF IA – GF IA – GF IA – GF IA – GF IA – GF IA – GF IA – GF MN – GFOH – GF
22CO – SOW CO – SOW IA – GF IA – GF IA – GF IA – GF IA – GF IA – GF IA – GF OK – GF
23IA – SOW IA – SOW GF OH MN – ??
24IA – GF IA – GF IA – GF IA – GF IA – GF CO – GF CO – GF MN – GFMN – GFMO – GFMN – ??
2534 GF 7 SOW2 UNKNOWN
Veterinary Diagnostic LaboratoryIowa State 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 ?
SowGrowing
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)
Clinical Signs
• Clinically indistinguishable 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
Diagnostics
• PCR – ready quickly
• Serology– IFA
– ELISA
• No VI – virus is difficult to grow
• Bioassay to prove infectivity/viability– Time consuming
– Expensive
– Lacks sensitivity
0% 0%
25%
70%
95%100%
0%
20%
40%
60%
80%
100%
120%
Week 1 Week 2 Week 3 Week 4 Week 5 Week 6
PED virus
• New to 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
Response
• USDA designated PED 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
AASV Response
• Collaboration with 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
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
Survey Results
• Only seven 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.
Epidemiology – Observational Study
Question topic Type of VariableOdds
Ratiop value Interpretation
How many pelleted rations were fed to
sows during the last 90 daysContinuous 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 daysContinuous 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 daysContinuous 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 daysContinuous 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 dietCategorical 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.
Response
• Development of 3 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
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
Research
• NPB, NPPC and AASV funded a study by Dr. Jim Lowe to look at transmission in harvest plant lairage.
Lairage Study
• Trailers do become contaminated at packing plants due in part to movement of drivers
• The more contact that occurs, the higher the rate of contamination
One positive trailer in means 1.7 positive trailers at exit
PlantContaminated
at entryContaminated
at PlantContamination
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
Research
• Dr. Matthew Turner 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
Future research focus for 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
Feed as a possible 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
Feed TestingMay-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 obtainedfrom the blender. The bioassay pigs did not show evidence of infection throughtesting 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.
Feed as a possible vector
• Dr. Scott Dee – has been able to transmit PEDvvia feed to naïve pigs
• Canada achieved a positive bioassay using spray dried porcine blood plasma but not feed pellets
AASV FEEDBACK SURVEY
Preliminary Results
Feedback Survey
• Asked vets 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.
% Sows with diarrhea
% Anorexic sows % IFA + % ELISA +
Feedback Success/Failure
65 100 100 S100 95 100 F80 40 95 F
100 100 100 F90 95 86 63 F70 90 100 F80 90 80 F30 30 100 S50 90 100 F50 90 100 F50 80 100 F35 35 92.5 99 F30 85 100 100 F95 70 98 F35 35 100 S50 40 100 S75 100 98 S
Educational Outreach
• AASV.org
• Pork.org
• Lab diagnosis needed for determining site status
• Managing biosecurity or biocontainment
• Specifics of specimen collection
• Feces
• Oral fluids
36
Guidelines for Diagnosis of PED Virus
37
PED Biosecurity Guidelines
38
PED Biosecurity Guidelines
Current Statusas of 5/10/14
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
Courtesy of NAHLN
Canadian Experience
• January 23 – 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
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
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
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 transboundarydiseases
• We are seeing “rebreaks” in 30 – 40% of herds
• Swine Deltacoronavirus introduction???
Swine Deltacoronavirus
• Clinically looks 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
Acknowledgements
• Dr. Matt Ackerman – Swine Vet Services
• Dr. Rodger Main – ISU VDL
• Dr. Brian McCluskey – USDA CEAH
• Dr. Paul Sundberg -- NPB