This document discusses the ongoing challenges of influenza on hog farms and the strategies being used to address it. Influenza is caused by a rapidly changing RNA virus that can infect multiple species. The farm is focusing on protecting breeding herds through monitoring, vaccination, and evaluating new vaccine technologies. Growing pigs are currently not vaccinated due to challenges like maternal antibody interference. Autogenous vaccines are being targeted to the most prevalent isolates found through sow herd monitoring. Questions around the best timing and ROI of growing pig vaccination remain open issues.

1. STILL STRUGGLING WITH
INFLUENZA….BUT HERE IS HOW I’M
APPROACHING IT.
JEREMY S PITTMAN, DVM, MS, DABVP
SMITHFIELD HOG PRODUCTION – NORTH REGION
WAVERLY, VIRGINIA

2. BACKGROUND
• Influenza is a persistent pain – “Big 4” and cost
• “Shifts and Drifts” : RNA virus  ever changing
• H1N1s, H1N2s, H3N2s, H?N?s,
• α, β, γ, δ1, δ2, cluster IVA, IVB
• Pandemics and Human Seasonals
• “It’s Seasonal” – NO, it’s a full time disease
• “Flu” – This is not your Grandpa’s Flu
• Zoonotic and interspecies (poultry and water fowl)
• Vaccine “options”

3. SUPPORTING THOUGHTS AND RESEARCH
• Gilts as a source (Diaz, Leman 2012; AASV 2014; Chamba, Leman 2017)
• Maternal Antibody interference, variation, infxn prevalence and transmission
dynamics (Allerson, Vaccine 2013)
• Sow Vaccination strategies (Allerson, Vaccine 2013; Chamba, AASV 2016; Chamba,
Leman 2017)
• Multiple isolates within breed and wean-to-finish (Diaz, AASV 2014; Leman 2014)
• Wean pig stability and reservoir? (Diaz, Leman 2012; Allerson 2013; Chamba, AASV
2017)
• Original Antigenic sin (Fazekas de St, J Exp Med,1966)

4. CURRENT STRATEGY
• Monitor multiplication and gilt development
• Protect the breeding herds (flu break abortion and downstream
impact)
• Stabilize the sow farms (elimination?) (Thompson, Leman 2016)
• Produce a robust wean pig (Flu, PRRS, PCV2, Myco, Age/Weight)
• Actively monitor breeding herds
• Utilize and evaluate autogenous killed vaccines (pending New
Technologies)

5. DIAGNOSTICS
Type Populations Advantage Disadvantage
Oral Fluids1 Growing pigs, gilts,
group housed sows
Increased population
sampling
Moderate Sequence, Poor VI
Snout Wipe2 Suckling pigs Easy, Increased
population sampling
Moderate Sequence, Poor VI
Nasal Swabs Suckling pigs, Clinical
cases
Successful Sequence, VI Targeted animals, “hard to
do”
Tissues Clinical cases Confirmation of lesions,
successful VI
Requires pig, “after the fact”,
random
1Detmer, AASV, 2010; 2Dobesh AASV 2012, 3Garrido, Leman 2017

6. MULTIPLICATION MONITORING
• 4+ years
• Sow Farms: Snout Wipes, Suckling piglets, 10 litters, every 2 weeks
• Nursery/Gilt Finishers: Oral Fluids, 2 ropes per barn, monthly
• Very few instances of flu to date:
• Pandemic H1N1; human seasonal H3N2
• “Self limiting”

7. COMMERCIAL BREEDING HERD MONITOR
• Started July 2016
• Monthly sampling: Snout wipes, 10 litters (coughing if present)
• If PCR positive
• ct <35  Attempt Sequence
• ct <30:  Sequence and Attempt Virus Isolation
• Re-Sampling with targeted Nasal Swabs for VI

8. May-17
Grower # 17-18 17-19 17-20 17-21 17-22 17-23 17-24 17-25 17-26 17-27 17-28 17-29 17-30 17-31 17-32 17-33 17-34 17-35
2003 X X X
2568 X X UKN
6105 X X X
6231 H1N2 H1H3N1N2 X X
6276 X X X
91111 X X X
91251 X N1N2 X
91261 X X X
91311 H1N2 X
91321 X X X X
91331 X X X
91341 X X X
91351 X X X
91361 H1N1N2 X X
91371 X N2 X
91391 X X X X
91401 X X X
91511 X X X
91521 X X X
94403 X X X
94405 X X H1N1
94418 X X X
94429 X X X
94431 X X X
94435 X X X
94437 X X X
94441 X X X
94443 X X X
94451 X X X
98023 X X X
98059 X X X
98063 X X X
99379 X X X
99625 X X X
99627 H1N1 X X
99648 X X
17-AugJun-17 17-Jul

9. VACCINATION STRATEGY
• Seasonal whole herd – twice per year (Spring-Mar and Fall-Sept)
• Additional if needed on individual herds
• Pre-Farrow (2-3 wks)
• Gilt Farms
• Unstable Herds – positive wean pigs, clinical post weaning
• Double mass vaccination if significantly new isolates (original
antigenic sin)

10. AUTOGENOUS VACCINE STRATEGY
• Target most prevalent and consistent isolates across system (Flows,
Geography)
• Prioritize candidates from sow farm monitoring
• Compare current vaccine isolates with current field isolates; both
monitoring isolates and clinical growing pig cases (cross HIs if warranted)
• Evaluate sow herd response to new isolates/formulations (homologous
HIs)
• Utilize commercial vaccine if and where sequence evaluation supports

11. GROWING PIG VACCINATION
• Currently not vaccinating growing pigs
• Challenge of when to vaccinate:
• Maternal interference
• “Start vaccinating when maternal antibodies wane at 10 wks of age”
• Decay varies by H-type
• Variation of Mabs in wean population
• Circulation of influenza in population during nursery phase or unstable
sow farm
• ROI on vaccinating growing pigs has not been there

12. SUMMARY
• Flu continues to be a significant pathogen – “Big 4”
• Many layered challenges with controlling the disease
• Focus is on breeding herds at this time
• Do not have the tools currently to effectively and consistently
control flu
• Continue to support and evaluate new technologies

13. QUESTIONS?

14. Auto Vax Auto Vax

16. Modeled Percent SIV Ab Negative Through Nursery
0.0%
10.0%
20.0%
30.0%
40.0%
Wean 2wk 4wk 6wk 8wk
Week Placed
PercentNegative
0.0%
20.0%
40.0%
60.0%
80.0%
100.0%
CummulativePercent
Negative
H1 Wkly % H3 Wkly % H1 Cumul % H3 Cumul %

17. Wean Pig Homologus HI titers from sows vaccinated with Heterologous
isolates
30.87
47.14 52.26
101.96
15.18
216.91
325.89
242.51
303.79
113.14
0.00
50.00
100.00
150.00
200.00
250.00
300.00
350.00
A (C1X) B (C2X) C (W1X) D (W2X) O (CNT)
Treatment Group
GeomeanTiter
HI A (WEST) HI B (CENT)
Tx Group 5 weeks Pre-Farrow 2 weeks Pre-Farrow
A ---- EAST
B EAST EAST
C ---- WEST
D WEST WEST
O ---- ----