Update on Porcine Reproductive & Respiratory Syndrome (PRRS) stability studies and flash updates on PRRS detection and biosecurity studies - Dr. Daniel Linhares, Iowa State University, Swine Health and Productivity, from the 2016 North American PRRS Symposium, December 3‐4, 2016, Chicago, Illinois, USA. More presentations at http://www.swinecast.com/2016-north-american-prrs-symposium

1. Update on PRRS stability studies…
and quick updates on PRRS detection and
biosecurity
Daniel Linhares
Veterinary Diagnostic and Production Animal Medicine [VDPAM]
Iowa State University

2. Agenda:
Update on PRRS stability
| SHMP 1-7-4 project
| Next steps to decrease stability?
Oral fluids-based slaughter surveillance [preliminary]
Oral fluids from suckling pigs [for breeding herd monitoring]
Detecting outbreaks a few weeks earlier…
What’s new on measuring “anti-PRRS biosecurity”?
What’s on the pipeline?
Controlling PRRS
Detecting PRRS
Preventing PRRS
More PRRS…

3. Couple field studies on PRRS stability…
2009-2013 study
• Acutely infected breeding herds
• Load + close + expose program
• Agreement to test (30 litters/month)
• Key demographic info:
• 50% infected with 1-4-4 PRRSv
• 50% prior PRRS history (3 years)
• 61 farms, 16 systems
2014-2016 study
• Infected breeding herds
• Not required to close or to expose
• Agreement to test (30 litters/month)
• Key demographic info:
• All infected with “1-7-4” virus
• 107 farms, 5 systems
PRRS control
Linhares, Cano, Torremorell, Morrison. Prev Vet Med, 2013 Betlach, Linhares, Morrison. in prep.

4. Early TTS is possible
PRRS control

5. 44
weeksTTS50
38
weeks
TTBP50
Success rate to reach Stable
Main outcomes, 2013 and 2016 studies (TTS @ last testing)
Early ones: 24-28 weeks
2013 2016
18
weeks
2016
25
weeks
2013
80%
49/61
2013
62%
67/107
2016
PRRS control

6. Median TTS (95th confidence interval):
2013 study 38.3 (35 – 42) weeks
2016 study 44 .0 (41 – 52) weeks
2013 cohort achieved TTS sooner than 2016 herds
1/3 of 2016 herds did not reach TTS by 52 weeks
TTSProbabilityPRRS control

7. All herds: closure was associated with faster TTSPRRS control

8. TTS at Birth
Hunter & Morrison, 2016
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
7 12 17 22 27 32 37
PercentPositivePools
Weeks Post Detection
Percent PCR Positive Pools By Weeks Post Detection For All Farms
TTS @ Birth
Median time: 21.2 weeks
Range: 8 to 32 weeks
 PRRSv RNA RT-PCR from blood,
tail blood swabs, or placental
umbilical cord serum (PUCS)
 Litters < 24 hrs old
 No cross-fostering
PRRS control

9. Project to reach Stable:
• 60 to 80% success rate
• 24 to 60 weeks to reach the 4th negative test
TTS and Probability to reach Stable were better in the 2009-2013
cohort (61 herds) compared to the 2014-2016 cohort (107 herds):
• Herd closure? Whole-herd exposure? PRRSv itself?
TTS at farrowing:
• 20 weeks (best= 8wks) answer in farrowing room?
PRRS control
Summary data from 168 sow farms
attempting to achieve stability

10. What else to (consistently) reduce TTS?
Biosecurity
(to reduce
re-breaks)
Boost (herd)
immunity
Reduce
within-herd
transmission
PRRS control

11. PRRS detection
Oral fluids-based slaughter
surveillance
Marcelo Almeida, Jeff Zimmerman,
Daniel Linhares
At the farm
PRRS RNA
Positive (PCR)
PRRS RNA
Negative (PCR)
Oral fluids 79 (25%) 240 (75%)
Serum 6 (2%) 310 (98%)
Oral Fluids
PRRS RNA
Positive (PCR)
PRRS RNA
Negative (PCR)
Farm 79 (25%) 240 (75%)
Abattoir 33 (34%) 63 (66%)

12. VDL Serum OF Farm OF Abattoir
Lab1 295/316 (93.35) 319/319 (100.0) 96/96 (100.0)
Lab2 291/315 (92.38) 320/320 (100.0) 96/96 (100.0)
Lab3 299/316 (94.62) 319/319 (100.0) 96/96 (100.0)
PRRS ELISA by sample: 93% serum, 100% oral fluids were positive
VDL Serum OF Farm OF Abattoir
Lab1 32/32 (100.0) 32/32 (100.0) 32/32 (100.0)
Lab2 32/32 (100.0) 32/32 (100.0) 32/32 (100.0)
Lab3 32/32 (100.0) 32/32 (100.0) 32/32 (100.0)
PRRS ELISA by group: 100% of groups were positive
PRRS detection

13. VDL Serum OF Farm OF Abattoir
Lab1 5/32 (15.63) 22/32 (68.75) 17/32 (53.13)
Lab2 8/32 (25.00) 21/32 (65.63) 12/32 (37.50)
Lab3 5/32 (15.63) 24/32 (75.00) 11/32 (34.37)
VDL Serum OF Farm OF Abattoir
Lab1 6/316 (1.90) 79/319 (24.76) 33/96 (34.38)
Lab2 10/315 (3.17) 67/320 (20.94) 26/96 (27.08)
Lab3 6/316 (1.90) 80/319 (25.08) 21/96 (21.88)
PRRS PCR by sample: ~2% serum, ~24% Farm OF, ~28% Abattoir OF
PRRS PCR by group: ~ 18% serum, ~65% Farm OF, ~40% Abattoir OF
PRRS detection
Serum: 97.5 – 99.1% agreement between VDLs
Oral Fluids: 82.3 – 88.5% agreement between VDLs

14. Farm PRRS PCR OF
Farm PRRS PCR serum
↑ PRRSv @ farm =
↑ PRRSv @ abattoir
PRRS detection

15. Take home messages [preliminary]
• OF easily collected at abattoir
• PRRSv antibodies + SVA/PRRSv RNA can be detected on oral fluids
collected at abattoir
• PRRSv RNA detection: higher in OF compared to serum
• Variation in agreement between labs (SVA and PRRSv PCRs)
• Need to further explore farm-abattoir agreement: farm prevalence,
number of ropes, pig behavior, summer vs winter conditions

16. Example chart to detect outbreaks using # aborts/week:
Note spikes in abortions & changes in SHMP status over time
VDPAM
weeks
PRRS detection

17. Increased Not increased
Yes 10 (100%) 0 (0%)
No 7 (0.5%) 1,381 (99.5%)
Number of abortsPRRS
Outbreak
Increased Not increased
Yes 10 (100%) 0 (0%)
No 5 (0.4%) 1,353 (99.6%)
Pct preweaning mortality
PRRS
Outbreak
Increased Not increased
Yes 5 (100%) 0 (0%)
No 5 (0.4%) 1,363 (99.6%)
Pct preweaning mortality
PED
Outbreak
Notes:
Abortion wave was also
detected in one PED
outbreak (1 week before
changing status to PED 1)
Time to detect PRRS =
“zero”: PWM used to
define outbreak?
PRRS detection

18. Analytic Hierarchy Process to measure biosecurity
Level 1
1. Pig movements
2. Pickup/Deliveries
3. People movement
4. Pork/food product entry
5. Manure removal
6. Domestic animals, feral swine,
other wild animals and insects
7. Air and water
Level 2
a. Semen delivery
b. Replacement pigs
c. Cull pigs from premises
d. Weaning
Level 3
a. Semen itself
b. Semen packaging
c. Vehicle and driver
A) Structure biosecurity risk by categories of events (Holtkamp)
B) Relative importance of each category
C) Relative importance of sub-categories
0.449
0.028
0.189
0.052
0.125
0.069
0.089
1.00
0.23
0.57
0.12
0.08
1.00
0.77
0.08
0.15
1.00
Frequency of events * risk of events = Score
Gustavo Silva, Derald Holtkamp, Daniel Linhares
PRRS prevention

19. Analytic Hierarchy Process to measure biosecurity
A) Structure biosecurity risk by categories of events (Holtkamp)
B) Relative importance of each category
C) Relative importance of sub-categories
Gustavo Silva, Derald Holtkamp, Daniel Linhares
PRRS prevention
Pilot data, 30 farms:
Score was positively
correlated (0.65) with
frequency of outbreaks.
Number of PRRS outbreaks, last 5 years
Finalscore

20. Description of biosecurity aspects of herds with low or high PRRS
incidence and comparison within and between production systems
Linhares, Holtkamp, Morrison, Arruda, Silva & Vilalta
density
# key
events
selected
practices
Infra-
structure
 Differences,
commonalities?
 Trends?
 Scores associated with
frequency outbreaks?
PRRS prevention

21. Thank you:
Daniel Linhares DVM MBA PhD
VDPAM, Iowa State University
Linhares@iastate.edu
http://field-prrs.blogspot.com/
Abattoir study:
Dr Dion
Dr Donovan
Dr Murray
Dr Wiseman
Dr Sundberg

22. Evaluation of methods for oral fluid
collection on due-to-wean piglets
Marcelo Almeida and Daniel Linhares
Source: Yeske-Livermore, L (2014) Source: Graham, J (2013)
PRRS detection

23. Factors associated with obtaining
oral fluids from suckling pigs:
(Marcelo Almeida)
 Piglet age: 3 wks old pigs more active than younger pigs
 Time of the day: the earlier it was the rope exposure, the higher it
was the success rate (Best ~ 6 AM; Poor ≥ 8 AM)
 Substrate: peanut butter slightly improved success rate (extra work)
 Rope height from floor: better when rope is close to floor
 Family sampling: superior (>80%) than litter sampling (~40%)
 Prior training: improved the litter sampling success rate (+20%).
PRRS detection

24. Litter Sampling
Family Sampling
Dr Marcelo Almeida
PRRS detection

25. 10%
90%
CTRL-FAMILY/CTRL-LITTER
20%
80%
CTRL-LITTER/CTRL-LITTER
15.07 ±
11.08 mL
14.42 ±
13.17 mL
2.35 ± 1.87
mL
3.44 ± 2.68
mL
4.13 ± 2.98
mL
3.63 ± 1.58
mL
SuccessCriterion=0.5mL=91.66%Success
100%
PEANUT-FAMILY/PEANUT-FAMILY
100%
CTRL-FAMILY/CTRL-FAMILY
10%
90%
PEANUT-FAMILY/PEANUT-LITTER
10%
90%
PEANUT-LITTER/PEANUT-LITTER
30%
70%
NO TRAINING/PEANUT-LITTER
40%
60%
NO TRAINING/CONTROL-LITTER
4.70 ± 4.11
mL
4.87 ± 2.23
mL

26. Thank you:
Daniel Linhares DVM MBA PhD
VDPAM, Iowa State University
Linhares@iastate.edu
http://field-prrs.blogspot.com/
Abattoir study:
Dr Dion
Dr Donovan
Dr Murray
Dr Wiseman
Dr Sundberg