Dr. Daniel Linhares - PRRSv Control & Elimination Strategies For Swine

IOWA STATE UNIVERSITYVeterinary Diagnostic and Production Animal Medicine

PRRSv control & elimination strategies

Daniel Linhares, DVM, MBA, PhDAssistant Professor & Director of Graduate

Education, Veterinary Diagnostic and Production Animal

MedicineIowa State University College of Veterinary Medicine

January 28th, 2016.Des Moines, Iowa


Outline• Immunization strategies for PRRSv

control• Looking at 174 impact on growing

pigs• PRRS metrics… tracking progress


PRRSv Agenda• Improving prevention of PRRSv

infection• Reaching stability faster, with less

impact

• And… how to measure (success)?


IMMUNIZATION STRATEGIESAchieving herd immunity


LVI

MLV

0 10 20 30 40 50

PRRSv Load-Close-Homogenize programs: 1-year timeline

Time (weeks)

Trea

tmen

t

TTSTTBP Silent PRRS (!)

TTSTTBPSilentPRRS

virus sheddingno signs

Production level was not good predictor of time-to-negative. Biosecurity and management practices should remain strict until Negative

Linhares, Cano, Torremorell, Morrison, Prev Vet Med, 2013


Median TTS and 95% CI:Prior_infect.: 26.00 (20.71, 30.57)No prior inf.: 32.57 (26.28, 38.00)

(Log rank p-value 0.0066)

Prior PRRSv-infection: yes vs noTi

me

to st

abilit

y pr

obab

ility

Linhares et al., 2013

Linhares, Cano, Torremorell, Morrison, Prev Vet Med, 2013


Economically worth it to preventively vaccinate herds to “build” PRRSv herd

immunity?

Lower production

impact if wild type PRRSv is introduced*

Continuous impact on PSY, growth performance**

It depends on frequency of PRRSv introduction

* Linhares et al., 2013**Johnson, 2013 (field data); Bøtner et al., 1997; Dewey et al., 1999 and 2004; Nielsen et al., 2002


Considering attenuated PRRSv impact: 1.5 PSY, $ 1.00 growth performance Break even = 1 year & 9 months

Linhares D, Johnson C, Morrison R. PLoS ONE, 2015.

Economic benefit of “preventive vaccination” for PRRSv: depends on frequency of breaks

0.25 0.5 1 2 31.21.31.41.51.61.71.81.9

22.1

Break-even of preventative vaccination based on impact of attenuated PRRSv on growing pig per-

formance, assuming impact on breeding herd of 1 PSY

Cost of attenuated PRRSv on growth per-formance (USD)

Freq

uenc

y of

PRR

Sv-in

trod

uctio

n (y

ears

)

0.1 0.3 1 1.5 1.7 21

1.2

1.4

1.6

1.8

Break-even of preventative vaccination practice based on the impact of attenuated PRRSv on PSY,

assuming no impact on growth performance

Reduction in Pigs weaned per sow per year (PSY)Fr

eque

ncy

of P

RRSv

-intr

oduc

tion

(yea

rs)


COMPARING CONTROL & ELIMINATION PROTOCOLS

PRRS metrics


Best strategy?

SuccessTime to produce negative pig Time to baseline production Total loss attributed to PRRS

Practices to control PRRSv infectionGilt exposure

Time gilt exposed to sow farm

introduction

Sow exposure program

bio-management practices

Frequency of whole herd exposure

Herd closure-associated practices

Herd characteristics and PRRSv infection historyprior

immunitynearby swine

densityfrequency of virus

introductionbuilding layout

overall biosecurity level

parity segregation, batch farrowing

PRRSv status and PRRSv genetic line

Proposed model: Linhares & Holtkamp


Linhares, Levis, Wedel, Betlach, Morrison. Leman conf, 2015.


Goals#1 Understand WTF mortality

drivers

#2 Assess 174-PRRSv role on mortality and on profit (loss).


Materials and Methods• Developed a model* to combine

information from difference sources to explain a health-associated parameter (mortality):– Swine health information (SHMP)– Sow farm parameters–Management parameters– Closeout (growing pig performance)

data* Hierarchical mixed model using SAS University Edition Proc Glimmix


2,080 closeouts7,323,511 pigs41 sources

1,465 closeouts4,431,762 pigs

35 sources

Single source

Wean to finish462 closeouts2,362,511 pigs

33 sources


Summary of effect of parameters on Mortality

Variable Levels Significant?

Feed Mills N=12 YESSupervisor N=30 YESPct Utilization Continuous YESSow farm PRRSv status 1, 2v, 4 YESStart weight Continuous YESPRRS type (174, other, none) YES

Sow farm PEDv status 1, 2v, 4 TREND

Gilt type Bred vs 270lb TREND

Density Continuous NO

Average Parity # Continuous NO

Herd Parity # Continuous NO

Empty days before start Continuous NO


1-7-4 PRRS

“other” PRRSv

Stable sow farms




Actual vs predicted mortality (95% prediction ellipse)

Variables. PRRS virus (174, other, none); Weeks on PRRSv status (nested with source); Start quarter (time); Gilt type; Supervisor; Feed Mill; PEDv status; Pct utilization WTF

Actu

al M

orta

lity

Predicted Mortality

1-7-4 PRRSv flows:+4.8% mortality-$ 2.87 / head profit



Final comments• Biosecurity: room for improvement (science and

$)• Definition of “success” varies – so does selection

of control/elimination strategy (no silver bullet)• PRRSv is “smart”:

– Moving target to vaccines; transmits indirectly by many ways; vaccines don’t prevent infection/ shedding

– However, we do have ‘ready to go’ tools to significantly improve: time to stability, time to baseline productivity, interval between breaks, success rate of elimination projects (setting expectations is key)


Acknowledgements• Dr Alex Ramirez• Dr Bob Morrison• Dr Chris

Rademacher• Dr Clayton Johnson• Dr Derald

Holtkamp• Dr Ian Levis• Dr Jean Paul Cano

• Dr Katie Wedel• Dr Jeff Zimmerman• Dr Locke Karriker• Dr Montse

Torremorell• Dr Noel Williams• Dr Pat Halbur• Dr Reid Phillips


Daniel Linhares, DVM, MBA, PhDAssistant Professor & Director of Graduate EducationVDPAM - Veterinary Diagnostic and Production Animal MedicineISU CVM - Iowa State University College of Veterinary MedicineOffice: (515) 294-9358 | Mobile: (515) [email protected]://field-prrs.blogspot.com

THANK YOU VERY MUCH!

http://field-prrs.blogspot.com/

http://field-prrs.blogspot.com/


PRRSv control & elimination strategies

Daniel Linhares, DVM, MBA, PhDAssistant Professor & Director of Graduate

Education, Veterinary Diagnostic and Production Animal

MedicineIowa State University College of Veterinary Medicine

January 28th, 2016.Des Moines, Iowa



DEFINING SUCCESSPRRS metrics


Definition of “stable” or “negative”

• Monitoring breeding herd:– 4 * 30 rule on piglet blood (PCR 1:5)Assumptions:“PRRSv can not sustain infection in the breeding

herd for 3 months with prevalence below 10%”“Ability to detect PRRSv in piglet blood represents

status of PRRSv (shedding) in the breeding herd”

Are these assumptions correct?


For herds that achieved TTNP :80% LVIs and 86% MLVs reached AASV Category III

Failures:LVI: 2 new, 5 old; MLV: 2 new

OLD and NEW OLD only

Failure (reinfected)

Success (negative)

LVI 7 (20%) 28 (80%)

MLV 2 (14%) 12 (86%)

P = 0.2979


Success (negative)

LVI 5 (15%) 28 (85%)

MLV 0 (0 %) 12 (100%)

P = 0.1943

Linhares et al, 2013


LVI v

s MLV

Herds 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 ...LVI.1 T T ★ T T TLVI.2 T ★ T T TLVI.3 T T T T ★LVI.4 T T T T ★ T T T TLVI.5 T T ★ T T TLVI.6 T T T ★ T T TLVI.7 T T T T ★ T T T TLVI.8 T T T T ★ T T TLVI.9 T T T T T T TLVI.10 T T T T T T ★ T T TLVI.11 T T T T T T T TLVI.12 T T ★ T T TLVI.13 T T T T ★ T T TLVI.14 T T ★ T T TLVI.15 T T T T new virus foundLVI.16 T ★ T T TLVI.17 T T T T T TLVI.18 T T T T ★ T T TLVI.19 T T T new virus foundLVI.20 T T T T T ★LVI.21 T T T T ★ T T TLVI.22 T T ★ T T TLVI.23 T T T T T ★ T T TLVI.24 T T ★ T T TLVI.25 T T T T T T T T TLVI.26 T T T TLVI.27 ★ T T TLVI.28 T T T T TLVI.29 ★ T T TLVI.30 T T T T T TLVI.31 T T T TLVI.33 T T T T TLVI.34 T T ★ T T TLVI.35 T ★ T T TLVI.36 ★ T T TLVI.37 T T ★ T T TLVI.38 T T TLVI.39 T T T T T TLVI.40 T T T T ★ T T TLVI.41 T T T

MLV.1 T T T T T T ★ T T TMLV.2 T T T ★ T T T TMLV.3 T T T T T T ★ T T T TMLV.4 T T T T T T T T T TMLV.5 T T T T T T TMLV.6 T T T T T T T ★ T TMLV.7 T T T T ★ T T TMLV.8 T T T T ★ T T TMLV.9 T T TMLV.10 T T T T T TMLV.11 T T ★ T T TMLV.12 T T T T TMLV.13 T T T TMLV.14 T T T TMLV.15 T T TMLV.16 T T T T T TMLV.17 T T ★ T T TMLV.18 T T TMLV.19 T T T TMLV.20 T T T T T T


Herds that adopted LCE and completed PRRSv monitoring:

70% LVI and 75% MLV reached AASV category III

Failures:LVI: 3 new, 9 old; MLV: 3 new, 1 old

OLD and NEW virus OLD only

P = 0.2441


Success (negative)

LVI 12 (30%) 28 (70%)

MLV 4 (25%) 12 (75%)


Success (negative)

LVI 9 (24%) 28 (76%)

MLV 1 (8%) 12 (92%)

P = 0.1574


Log-transformed Mortality

6.5%

30%1.2%

Health & Medicine

Dr. Daniel Linhares - PRRSv Control & Elimination Strategies For Swine