PRRS – The Challenge Continues

Cameron Schmitt, DVM, MS

Iowa Pork Congress - 2013

My Background

• 2002 graduate of Iowa State University

• Completed DVM and MS (Veterinary Microbiology)

• Joined Pipestone Vet Clinic in 2002

• Started Pipestone Vet Clinic of Iowa 2008

• Married, 3 boys

Outline

• Biosecurity Review

– Transmission

– Filtration

• Immunological Review

– Vaccines

• Sow Farm Clean up

• Epidemiological Data

• Summary Comments

PRRS Biosecurity

• Transmission via:

– Animals

– Semen

– Fomites

– Air

Biosecurity - Animals

• Animals are the highest risk for PRRS transmission

– They propagate the agent

– Shed in all secretions/excretions

Biosecurity - Animals

• Animals – Sow Herds – Gilts

– It is critical to have isolation/quarantine space for breeding herds

– Testing – placement and 2 weeks post placement

• Oral Fluids or Serum

• Wean-to-Finish sites

– All In/All Out flow

– Continuous flow sites tend to circulate PRRS and other diseases once infected

Biosecurity - Semen

• Semen is still a risk today

– Critical to work with a reputable source and understand their testing protocols

– Do not use semen until test cleared for the batch/boars that collection day

Biosecurity - Fomites

• Standardized D&D

– D&D = Disinfection and Down time

– All inanimate objects entering a farm subject to D&D

– Spray all materials, equipment, etc with Synergize and dry

– 1 hour and Dry are the critical elements – must meet both criterion

Biosecurity - Trucks

• Transport is highly correlated with most disease movement

• Are your trucks clean, really clean?

– Inspected?

– Audited?

– The industry needs to re-evaluate current transport biosecurity

Biosecurity - Air

• A lot of new knowledge – we continue to learn

Aerosols

• Viral quantities found in air were significantly higher in 2011 than in previous years

– Hypothesized strains continue to become more virulent/more readily shed

• Vaccination with Modified Live Vaccines significantly reduces aerosol shedding

– Vaccination of sites surrounding sow farms is a good idea

Challenge Control Room

(West)

D&D West

Challenge Vaccine Room

(East)

D&D East

* It was used one cyclonic collector for each room

Project 1: Experimental design

• Controls

• 1,000 pigs

• PRRSv infected

• 1-18-2

• Sham inoculated

• 2x saline

• Treatments

• 1,000 pigs

• PRRSv infected

• 1-18-2

• Vaccinated

• 2x ATP

Results (Linhares et al., Vaccine, 2011)

Outcome Vaccine group Control group

# PRRSV positive air days*

17 days

31 days

Duration of aerosol shedding*

45 days

70 days

* = Differences significant at p < 0.05

Project 2

• Recently completed:

– Vaccinate first

– Challenge second

– Outcomes: shedding and performance

Challenge Control Room

(West)

D&D West

Challenge Vaccine Room

(East)

D&D East

* It was used one cyclonic collector for each room

Experimental design

• Controls

• 1,000 pigs

• Sham inoculated

• 1x saline

• Challenged

• 1-18-2

• Treatments

• 1,000 pigs

• Vaccinated

• 1x MLV

• Challenged

• 1-18-2

Preliminary data: Air Sampling

Days From Inoculation

-27 -26 -25 -24 -23 -22 -21 -20 -19 -18 -17 -16 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

Treatment

Group

6/1

2/2

012

6/1

3/2

012

6/1

4/2

012

6/1

5/2

012

6/1

6/2

012

6/1

7/2

012

6/1

8/2

012

6/1

9/2

012

6/2

0/2

012

6/2

1/2

012

6/2

3/2

012

6/2

4/2

012

6/2

5/2

012

6/2

6/2

012

6/2

7/2

012

6/2

8/2

012

6/2

9/2

012

6/3

0/2

012

7/1

/2012

7/3

/2012

7/4

/2012

7/5

/2012

7/6

/2012

7/7

/2012

7/8

/2012

7/9

/2012

7/1

0/2

012

7/1

1/2

012

7/1

2/2

012

7/1

3/2

012

7/1

4/2

012

7/1

5/2

012

7/1

6/2

012

7/1

7/2

012

7/1

8/2

012

7/1

9/2

012

7/2

0/2

012

7/2

1/2

012

7/2

2/2

012

7/2

3/2

012

7/2

4/2

012

7/2

5/2

012

7/2

6/2

012

7/2

7/2

012

7/2

8/2

012

7/2

9/2

012

7/3

0/2

012

7/3

1/2

012

8/1

/2012

8/2

/2012

8/3

/2012

8/4

/2012

8/5

/2012

8/6

/2012

8/7

/2012

8/8

/2012

8/9

/2012

8/1

0/2

012

8/1

1/2

012

8/1

2/2

012

8/1

3/2

012

8/1

4/2

012

North -

NoVax 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 0 1 1 1 1 2 1 1 1 1 0 0 1 1 1 1 1 1 1 0 1 1 0 0 1 0 1 1 0 1 0 1 1

South -

Vax 0 1 1 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 2 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Days From Innoculation

35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56

Treatment

Group

8/1

5/2

01

2

8/1

6/2

01

2

8/1

7/2

01

2

8/1

8/2

01

2

8/1

9/2

01

2

8/2

0/2

01

2

8/2

1/2

01

2

8/2

2/2

01

2

8/2

3/2

01

2

8/2

4/2

01

2

8/2

5/2

01

2

8/2

6/2

01

2

8/2

7/2

01

2

8/2

8/2

01

2

8/2

9/2

01

2

8/3

0/2

01

2

8/3

1/2

01

2

9/1

/20

12

9/2

/20

12

9/3

/20

12

9/4

/20

12

9/5

/20

12

North - NoVax 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

South - Vax 0 1 1 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Filtered Farms

• Filter bypass continues to be a challenge

– Backdrafting through fans

– Filter Box design/seal

– Cracks, leaks, drains, etc.

Filter Farm Data

• Our data would indicate there is a significant reduction in the frequency of PRRS infections on filtered farms, but it isn’t perfect

• When comparing pre and post filtration, we are observing a 61% reduction in new viral introductions

The impact of air filtration is significant, but not perfect

-40 -30 -20 -10 0 10 20 30 40

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

Time pre and post air filtration (months)

Bre

ed

ing

he

rds

Pre-filtration

Postfiltration

New PRRSV infection

How often are farms challenged?

------ PRRS

Recipient Populations: Perimeter Testing

5 filtered farms selected for sampling • Recipient farms (PRRSV-negative)

– n = 4 – sampled 30 m outside of building – collector placed into direction of prevailing wind

• Source farm (PRRSV-positive) – n =1 – sampled at exhaust fan – 1 mile SE of neighboring recipient farm

Daily air sampling: March 1-31, 30 minutes per day

Outcomes – Frequency: # PCR-positive air days – Dose: Quantity of viable virus (TCID50/mL) – Diversity: ORF 5 sequencing of selected samples

Farm 4

Farm 3

Results Frequency

Farm number PRRSV positive air days

1 (recipient) 64%

2 (recipient) 41%

3 (source) 75%

4 (recipient) 65%

5 (recipient) Historical

0% 3-11%

Farm1

Farm2

Farm 3

Farm 4

Historical

Dose

L

og

con

cen

trat

ion

vir

us

Farm

Farm 1a

Farm 2a

Farm 3a

Farm 4a

Historical b

ANOVA

Diversity

0

1

2

3

4

5

6

1 2 3 4

1-18-2 (new) 1-26-2 (new) 2-5-2 (MLV)

1-18-2 (old) 1-18-2 (new) 1-26-2 (new) (n=2)

1-3-2 (source) (n=2) 1-26-2 (source)

1-3-2 (source), 1-8-4 1-4-2 (ATP) 1-26-2 (source)

Farm number

# s

equ

ence

s

Recipient

Recipient Recipient

Source

Conclusions

• Under the conditions of this study: – 1. Viral loads in aerosols from source populations infected with

new variants were significantly higher than historical levels.

– 2. PRRSV aerosol challenge of recipient populations was a frequent event.

– 3. Viral loads in recipient aerosol samples collected at the perimeter level were significantly higher than historical levels.

– 4. Extensive viral diversity was observed in air samples collected around the perimeter of recipient populations.

Slurry

• Pigs shed PRRS in feces for 7 days • Virus survives in slurry for 14 days at 40 degrees and 5

days at 50-60 degrees • Virus survival in solids is less than 14 days in standard

pit environments • Virus is aerosolized during agitation if population is

shedding virus • Virus can be found at least at 30 meters from

applicators during application • Pumping equipment can be fomites for transmission of

virus

Slurry application risk: Proof of concept

PRRS Immunology

• Vaccines – New vaccine in the market

– Modified Live Products • PRRS MLV – Boehringer Ingelheim

• PRRS ATP – Boehringer Ingelheim

• Fostera PRRS – Pfizer

– Killed Products • MJ PRRS

• Sirrah

• Autogenous

PRRS Vaccines

• Ongoing research on efficacy

• Have been proven scientifically to:

– Reduce lung lesions

– Reduce duration of viremia

– Reduce shedding of virus via aerosols

– Improve certain production parameters

Load%close%homogenize0to0eliminate0PRRSv0from0acutely0infected0breeding0herds.0

0

Part01:0>me0to0neg0pig0produc>on0(TTNP)0Part02:0produc>on0analysis0(TTBP/total0loss)0Part03:0nega>ve0herd0(factors,0gilt0mgmt)0

Linhares D, DVM, MBA; Cano JP, DVM, PhD; Torremorell M, DVM, PhD; Morrison R, DVM, MBA, PhD.

10

Treatment:(LVI(vs(MLV(TTNP0probability0

Prior(PRRSvBinfec9on:(yes(vs(no(

80

Vaccinated0herds0had0significantly0less0total0loss0

LVI(herds(reached(nega9ve(sooner(

MLV(herds(had(less(total(loss(

PRRSv(monitoring(must(be(done(over(9me(

Median(9meBtoBnega9ve(was((~(210(days(

Herds(with(prior(PRRSv(infec9on(reached(nega9ve(sooner,(recovered(produc9on(faster(and(had(less(total(loss(

Farms(with(up(to(3(monthly(PCRBnega9ve(tests(with(produc9on(levels(“in(control”(might(s9ll(have(PRRSv(

circula9ng(at(low(prevalence(levels(

G(e(n(e(r(a(l((((((S(u(m(m(a(r(y(

Data Provided from Steve Tousignant, Bob Morrison Funding from National Pork Board

Data Provided from Steve Tousignant, Bob Morrison Funding from National Pork Board

Summary Comments

• As an industry, we need to continue to come together to prevent the spread of PRRS

• We need to utilize proven scientific knowledge, not just what might work/seems to work

• We need to continue to research disease movement, immunology, genetics, etc.

• We (as an industry) have cut many corners to decrease cost that are causing problems – Down time – Sanitation – Etc…

Acknowledgements

• Daniel Linhares

• Steve Tousignant

• Dr. Bob Morrison

• Dr. Scott Dee

• Pipestone Research Committee

– Dr. Scott Dee, Dr. Joel Nerem, Dr. Barry Kerkaert, Dr. Luke Minion, Dan Hanson