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How to control and eliminate PRRS from swine herds on farm and regional level Bob Morrison USDA PRRS CAP Coordinator University of Minnesota Outline •  Review of herd-­‐level PRRSv control and elimina@on •  Regional elimina@on efforts in the US •  Current challenges & opportuni@es Control •  Objec@ve – live with the virus but wean PRRSv nega@ve pigs –  PRRS nega@ve semen –  “McRebel” in farrowing –  Gilt acclima@on •  Resident virus •  Vaccine •  No PRRS virus –  Vaccina@on of sow herd Sampling Strategy •  Serum for virus or an@body •  “Random” sample •  95% / 5% = 60 samples •  95% / 10% = 30 “ •  95% / 20% = 20 “ •  95% / 30% = 10 “ •  Risk-­‐based sampling increases sensi@vity •  Aborted sows, lower viability suckling pigs Elimina@on •  Herd closure for farrow to wean sites –  Load with gilt replacements –  Close for at least 200 days –  Expose with resident virus or vaccine –  Nega@ve semen –  McRebel –  Monitor progress in weaned pigs Elimina@on •  Herd closure first described by Torremorell et al (2002 / 2003): –  “A PRRSV-­‐nega-ve popula-on was established from posi-ve sources by managing the gilt pool and batching the pig flow. –  It appeared that PRRSV infec-on, indicated by lack of seroconversion in the offspring, eventually either disappeared or became inac-ve.” J Swine Health Prod. 10(4):153-­‐160. PRRSV Compendium. Eds Zimmerman et al, 2nd Edition, National Pork Board, Des Moines, Iowa, p: 157-160
Time To Nega@ve Pig (TTNP) study •  34 sow herds exposed with: –  17 with live virus inocula@on (LVI) –  17 with modified live virus vaccine (MLV) •  Herd selec@on criteria  
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Farrow to wean herd Dx evidence of PRRS virus presence Elimina@on plan including closure No new PRRS virus introduc@on during closure Owners cover costs of diagnos@cs, collec@ng and shipping samples Dates of herd closure and whole herd exposure less than 15 days apart Preliminary results (Linhares, Cano, Torremorell & Morrison, 2011) Live virus MLV No. farms enrolled 23 8 No. farms reached nega@ve pigs 7 5 Average (weeks) 26.4 26.7 SD (weeks) 7.4 11.3 16-­‐30 12-­‐41 Range (weeks) Preliminary Observa@ons •  PRRSv low prevalence is hard to detect. From the 32 farms with ongoing PRRSv monitoring: •  12 farms: 1 month of PCR -­‐ result followed by + results •  2 farms: 2 months of PCR -­‐ result followed by + results •  1 farm had 3 months of PCR -­‐ followed by + results •  Wide range of TTNP (12 – 41 weeks) Change in no. pigs weaned for 52 weeks aier closure in 15 herds Schaefer & Morrison; SHAP 2007
Filtering sow farms (with complete biosecurity package) •  Non-­‐filtered groups had PRRS infec@on in 28/65 replicates (43%) compared to 0/101 replicates in filtered groups (Dee et al. 2011). •  85% reduc@on in annual rate of outbreaks aier filtra@on when compared to 5 years prior to filtra@on (Leman Conference 2011 -­‐ Reicks, Spronk, Ruen). •  Currently, approximately 200,000 sows filtered (Leman Conference 2011 – Malakowski) Choice •  High density –  High biosecurity including wind barriers, and possibly filter sow farm •  Low / moderate density –  Regional program to decrease risk S WI S WI (2011) (2011) P Bahnson P Bahnson PRRSV regional elimina@on •  Interna@onal: – Chile – declared PRRSV nega@ve in 2009 •  United States – Regional level: •  Started in Rice Cy, MN (2002-­‐2008) •  N212 MN (2004 – present) N212 MN Regional PRRS Elimina@on Program Dave Wright, Montse Torremorell, Bob Morrison Swine Health Center, Morris Vet Clinic, Nate Winkelman, Swine Vet Center, Neil DeBuse, Fairmont Vet Clinic & others N212MN Project •  N212MN funding •  IACUC: –  0711A21864 –  ’04 – ’06 -­‐ none –  ’07 – ’09 -­‐ USDA –  ‘10 – ’11 – PRRS CAP & UMN SDEC •  Rice •  Disclosure: –  RBM -­‐ 2 sow farms in Stevens Cy –  MPB –  BI PRRS Ini@a@ve –  AASV Stevens County Stevens County 2004 2004 ▲ Sows
■
Nursery
●
Finisher
Boar Stud
Show Pigs
Stevens County 293 pigs / mile2 28 sows / mile2 2011
2004
First Expansion Seven County Region Second Expansion N212MN Project: P.I. – Montse Torremorell Coordinator – Dr. Dave Wright Has sows Growing pigs, no sows nega@ve unknown posi@ve Morris vets Al Carlson Nate Winkelman Swine Vet Center Has sows Growing pigs, no sows nega@ve unknown posi@ve Known sites in the region • 
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73 sites with sows 34 sites with nursery pigs only 384 sites with finishing pigs 491 sites total •  6 buying sta@ons •  6 boar studs S WI S WI (2011) (2011) P Bahnson P Bahnson PRRS CAP website Sow herds in the region (& nurseries & finishers) Sow herd size
Farrow to wean
<=100
101-600
601-1500
1501-3000
1
1
13
12
Farrow to feeder
Farrow to finish
>3000
11
1
23
11
Sow herd size
Unknown
<=100
101-600
601-1500
1501-3000
17
5
8
1
2
1
1
1
4
10
8
Positive
Positive stable
>3000
Negative provisional
Negative
7
8
Current Issues & Workgroups: •  5 working groups •  Challenge of farrow to finish sites •  Failure of some closure programs Five working groups: 1.  Standard Of Prac@ce for sow herd management & sampling 2.  Minimum sampling guidelines for low risk sow herds and growing pig sites 3.  Risk based sampling 4.  Incorpora@ng oral fluids into sampling-­‐tes@ng guidelines 5.  Managing the risk of disclosure Standard Of Prac@ce for sow herd management & sampling •  Jim Lowe; assisted by Laura Ba@sta, Paul Yeske, Neil DeBuse, Bob Morrison –  What are guidelines for sampling and managing farrow to wean sow herds? Herd PRRS Status1 I (posiDve unstable) II (posiDve stable) III (provisional negaDve) IV (negaDve) Status Descrip@on 3: TransiDoning to 4: NegaDve -­‐ no ELISA 1A: AcDve InfecDon: 1B: Approaching 2A: Short Term Stable 2B: Long Term Stable NegaDve -­‐ nega@ve posi@ve and shedding & abor@ons stability: shedding -­‐ no shedding -­‐ no shedding gilt replacements previously infected and/or > 10% of pigs but less than 10% of detected for >= 8 detected for >= 6 mon remain seronegaive for sows have been infected at birth pigs infected at birth. weeks >= 2 mon removed Tes@ng to Prove Status2 All PCR nega@ve tail 60 PCR nega@ve swabs from 60 pigs serum samples (pool >= 30 gilts are PCR and (1 pigs per liter); 5) in four separate 6 months of nega@ve ELISA nega@ve at least pool 5 in four samplings from pigs at weaned pig tes@ng as Defaut State with out 2 months post separate samplings weaning. Ongoing determined on a case diagno@cs introduc@on and by case basis. at least 1 week apart monitoring every 4 remain nega@ve Ongoing sampling weeks of weaned pigs every other week. remain nega@ve Earliest to ini@ate tes@ng to confirm status aier herd closure n/a >= 22 weeks post Min of 182 days post infec@on infec@on and 4 6 months aier 1st neg (inocula@on) and consecu@ve nega@ve weaned pig tes@ng. pigs born dead <12% tests of >= 60 of TB 9 months 60 head PCR and ELISA nega@ve 30 days aier last previously posi@ve animal has lei the farm. Gilt Introduc@ons No No Prebreeding vaccines Prefarrowing vaccines No No Yes Yes Sow Management Yes – Prev. Yes Infected Yes Yes Yes Yes Change needles between sows and gilts Yes Yes Yes No No No No Manure feedback prefarrow Manure Feedback prebreeding Tissue or serum feedback Yes – Naïve Yes – Naïve Yes Yes Yes yes Yes No on nega@ves; yes on posi@ves No No No No Yes No Yes Yes Yes (nega@ve only) Yes No No No No Yes Farrowing House Management Prac@ces Allow Low Intensity washing Allow part weaning of rooms Change needles and blades between liters Tubs at farrowing Processing carts No No No No No Yes No No No Yes Yes Yes Yes Yes Yes No No No Yes No Yes Yes Yes Yes Piglet Movements Movements at less than 24 hours of age only for liter size3 No Yes Yes Fall back liter (1 nurse sow per 26 crates)4 No No No Pee Wee Liters5 Holding pigs at weaning for quality Replacing fallbacks in donor liter (>24h of age)
3,4
No on nega@ves; yes on posi@ves Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No No Yes Yes Yes No No No No No Yes No No No No No No No Minimum sampling-­‐tes@ng guidelines for low risk sow herds and growing pig sites •  Derald Holtkamp; assisted by Leigh Rosengren, Dale Polson, Paul Yeske, Bob Morrison –  What are recommended sampling guidelines for every site, every circumstance? •  Farrow to finish vs farrow to wean vs growing pig sites –  Number & frequency Risk based sampling •  Bob Morrison; assisted by Derald Holtkamp, Eric Bush, Enrique Mondaca, Leigh Rosengren, Dane Goede –  How can we used es@ma@on of risk of infec@on to help us op@mize herd-­‐level sampling? Density of +’ve 1/d2
of unknown 1/d2 of –’ve 1/d2
20 15 5
Status of source is unknown 15 Herd size of site Month since last test Site +’ve w/in 18 months
15
15
15
100
Incorpora@ng oral fluids into sampling guidelines •  Dale Polson; assisted by Jeff Zimmerman, Jean Paul Cano & Luc Dufresne –  How many ropes / airspace? •  Presumed posi@ve vs nega@ve groups –  Sugges@on for how much we can pool samples. Managing confiden@ality & the risk of disclosure •  Lisa Becton; assisted by Jim McKean, Bob Morrison & others –  What are current best prac@ces for managing confiden@ality? Managing Disclosure •  Knowing the neighbor’s PRRS status is a privilege. •  Pressure the neighbor and drive it underground. •  “Thank you for telling me. I’m sorry this is happening to you. Do you mind telling me your plans? Is there anything I can do to help?” •  Proposals on PRRS virus regional elimina@on ac@vi@es must: –  Describe how the team will synergize with and strengthen ongoing regional elimina@on ac@vi@es, –  Coordina@on with one or more similar interna@onal elimina@on efforts is encouraged. Outline •  Review of herd-­‐level PRRSv control and elimina@on •  Regional elimina@on efforts in the US •  Current challenges & opportuni@es Regional, Voluntary, Producer-­‐led, Coordinated Disease Control & Elimina@on Methods Herd enrollment process
1.  Initial interview (herd profiling and enrollment form)
2.  Fulfillment of herd selection criteria (YES/NO)
Farrow to wean herd
Dx evidence of PRRS virus presence
Elimination plan including closure
No new PRRS virus introduction during closure
Owners willing to cover costs of baseline diagnostics, collecting and shipping
samples
  Dates of herd closure and whole herd exposure are less than 15 days apart
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3.  Sign client consent form
PRRS ATP to pigs at 5-­‐10 days old aier herd closure 14.1%
8.1%
2.5%
2.95
%
Spronk et al; Leman Swine Conference 2009