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

ChallengeControlRoom

(West)

D&DWest

Challenge VaccineRoom

(East)

D&DEast

* 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

ChallengeControlRoom

(West)

D&DWest

Challenge VaccineRoom

(East)

D&DEast

* 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

Log

con

cen

trat

ion

viru

s

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), 1-8-41-4-2 (ATP)1-26-2 (source)

Farm number

# se

qu

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 MorrisonFunding from National Pork Board

Data Provided from Steve Tousignant, Bob MorrisonFunding 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