Download A PEDV re

A PEDV ­re-break
Matthew Ackerman, ­DVM
Swine Veterinary Services, Greensburg, ­Indiana
Introduction
On May 5, 2013 a 6000 sow farm in Indiana broke with
PEDV.1 The entire farm (including internal multiplication gilts in the onsite nursery and finisher) were given
Oral Live Virus Exposure – OLVE (feedback). This farm
lost 3.6 weeks’ worth of pigs over an 8 week period.2 Follow-up fecal testing (30 litters per week for 4 consecutive
weeks of negative results3) was successfully completed in
September 2013 (Table 1­ ).
During the OLVE, gilts were about the only animals that
responded clinically. Sows appeared to be immune to the
challenge. We were not very concerned about this since
we assumed the sows would have systemic immunity. We
theorized that the gilts in the breeding barn may or may
not have been exposed to PEDV in the nursery or finisher over the July to October 2013 time frame, though
gilts prior to July most likely would have been exposed to
­PEDV.
All during this time, gilts were retained on site (internal
multiplication) and were potentially exposed to virus in
the nursery and finisher. Once the 4 weeks in a row of
negative fecal were completed, oral fluids were collected
from the nursery and finisher showing that those locations had also gone PEDV negative (October ­2013).
For example, if a gilt was 1 month old in May 2013, she
would have been 11 months old in March 2014. So if she
was bred at 8 months of age, she was still almost 1 month
from farrowing at the time of the recurrence. Therefore
all of the animals older than that should have been exposed – ­protected.
The next 6 months of production went well (102% of
previous wean pig output) with minimal signs of scours,
of any kind, throughout the u­ nit.
Over the next 2 weeks in the farrowing house, PEDV
only seemed to hit Parity 1 and Parity 2 litters at about
70% and 50% pre-weaning mortality respectively. In
the subsequent weeks, PEDV spread into litters of all
­parities.
The ­recurrence
In mid-March 2014, scours were observed in the onsite
nursery and finisher. In the subsequent week, PEDV was
diagnosed of the same strain (99.9% homology) to the
May 2013 strain. Once the virus moved into the farrowing house, then the entire farm was re-given Oral Live
Virus Exposure (March 26, ­2014).
A comparison of the previous 2013 outbreak (3.6 weeks of
pigs lost or 1.73 pigs per sow per year) vs the loss over the
13 weeks until recovery is illustrated (4 weeks of pigs lost
or 1.92 pigs per sow per year) (Figure 1 and Figure ­2).
Those losses by parity of the Re-Break are shown in Figure ­3.
Table 1: Diagnostic monitoring results of original 2013 PEDV ­breaks
Outbreak week
Outbreak days
Production week
Calendar date
6000 sow
3600 sow
1
7
19
May 5 to May 11
Pos – F & Int
Pos – intestines
2
14
20
May 12 to May 18
Pos – intestines
Pos – intestines
8
56
26
Jun 23 to Jun 29
Pos – intestines
10
70
28
Jul 7 to Jul 13
Pos – fecal
14
98
32
Aug 4 to Aug 10
Pos – fecal
15
105
33
Aug 11 to Aug 17
16
112
34
Aug 18 to Aug 24
17
119
35
Aug 25 to Aug 31
18
126
36
Sep 1 to Sept 7
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Neg – fecal
Neg - swabs
Neg – swabs
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Figure 1 & Figure 2: Percent of 52 week prior - average pigs weaned per w
­ eek
May 2013 - 6000 Sow
119%
32%
Week 1
Week 2
Week 3
Week 4
Week 5
Week 6
Week 7
Week 8
Week 9
Week 10
Week 11
Week 12
Week 13
Week 8
Week 7
Week 6
0%
Week 5
Week 4 0%
Week 3 0%
Week 2
Week 1
0%
0%
50%
68%
79%
85%
60%
53%
52%
81%
57%
83%
103%
100%
21%
50%
May 2014 - 6000 Sow
150%
82%
64%
77%
100%
102%
150%
May 2013 - 6000 Sow
March 2014 - 6000 Sow
Figure 3: 2nd round - pre-weaning mortality by parity - 9 ­weeks
70%
60%
62%
50%
40%
37%
30%
24%
20%
20%
22%
17%
20%
21%
10%
5%
0%
Parity 1
422
Parity 2
Parity 3
Parity 4
Parity 5
Parity 6
Parity 7
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Parity 8
Parity 9 Parity 10
As time went on, the losses by Parity became more consistent, meaning that PEDV was affecting all parities closer
to the same in weeks 11 and ­12.
I am pleased to report, that of the 20 herds we had break
with PEDV in 2013-2014, this is the only herd that rebroke, thus f­ ar…
My objectives in sharing this information, i­ s:
1. To make people aware that PEDV can r­ e-break.
2. There are research opportunities for lactogenic immunity especially as it pertains to the g­ ilt.
3. Because of these chronic and recurring situations, we
have even more need for vaccine o­ ptions.
References
Summary
My key points from this ­information:
1. This is just one herd. Our other herds have not rebroke. (n of ­1)
2. PEDV can recur after 6 month of clinical ­absence.
3. We don’t know if this is recrudescence or a
­re-exposure
4. While I had hoped that gilts feedback would be immune and able to protect their subsequent offspring
in the face of a challenge, I am less sure of that today.
(Implications on gilt acclimation ­strategies.)
5. Despite this crew’s experience and “expertise” on
how to handle PEDV - PEDV went chronic in
this herd in spite of excellent people, facilities and
­sanitation.
1. Stevenson GW, Hoang H, Schwartz KJ, Burrough ER, Sun D,
Madson D, Cooper VL, Pillatzki A, Gauger P, Schmitt BJ, Koster LG,
Killian ML, Yoon KJ. August 2013. Emergence of Porcine epidemic
diarrhea virus in the United States: clinical signs, lesions, and viral
genomic sequences. J Vet Diagn Invest 25: 649–654. ­http://vdi.
sagepub.com/content/25/5/649.
2. Ackerman MA. October 2013. Acute cases of Porcine Epidemic
Diarrhea Virus in a sow farm and nursery. Pig333.com ­https://www.
pig333.com/clinical-case-of-the-world/acute-cases-of-porcineepidemic-diarrhea-virus-in-a-sow-farm-and-nurse_7587/.
3. Morrison B and Goede D. March 2014 Epidemiology and economic
impact of PED. AASV Proceedings 605–611 ­https://www.aasv.org/
library/swineinfo/Content/AASV/2014/605_Morrison.pdf.
4. Ackerman MA, Morrison B and Goede D. June 2014. PEDV Case
Report – Exposure after initial outbreak and potential re-infection. Swine
Health Monitoring Project. June 27, 2014. ­http://www.cvm.umn.edu/
sdec/prod/groups/cvm/@pub/@cvm/@sdec/documents/content/
cvm_content_483532.pdf.
American Association of Swine Veterinarians
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2015 AASV Annual Meeting: Beyond Our Oath: Integrity, Intensity, Professionalism
424
American Association of Swine Veterinarians