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Talking Animal Health - PRRS: The Challenge Continues - Dr. Cameron Schmitt, Pipestone Vet Clinic, from the 2013 Iowa Pork Congress, January 23-24, Des Moines, IA, USA. More presentations at http://www.swinecast.com/2013-iowa-pork-congress
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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