Swine influenza:
Current state, future impact and
what producers can do to reduce
their risk
Montse Torremorell, DVM, PhD
...
Introduction
• Influenza is a common cause of
respiratory disease in pigs
• Worldwide distributed
• Multiple subtypes and ...
UMN VDL 2008-2013
1000
900
800
700
600
500
400
300
200
100
0

Others
Untypable
H3 / N?
H3 / N2
H1 / N?
H1 / N2
H1 / N1
Influenza can be costly
• Economic impact
– $3.23 difference from baseline in loss per
head placed (Dykhuis Haden et al., ...
Current state
• 1. Gilts and weaned pigs can be a source of
influenza virus
Sub-population

N

Positive

Prevalence

Gilts...
How important are weaned pigs?
Sow farms

n=52

44% +

Sampling
Events

n=252

26% +

n=2,520

15% +

Pools
(pools of 3 sw...
Sampling event
Farm

1

2

3

1

H1

H1

4

Sampling event
5

H1

6

Farm

1

2

3

4

5

H1

H1

H1

6

H1

27

2

28

3
...
Farm
ID

1
9
11
13
19
25
30
35
36
37
38
40
44
47
50
51
52

Count of HA gene
sequences
compared

Subtype

Lowest % identity...
Current state
• 1. Weaned pigs are a source of
influenza virus
• 2. Infections in growing pigs are highly
prevalent
Current state
• 2. Infections in growing pigs are highly
prevalent
32 farms tested monthly
for 2 years (Jun 2009-Dec 2011)...
Epidemiology
Grow-finish surveillance

Corzo et al., 2012
Farm Identification Number

Genetic diversity in grow-finish sites

H1N1

pH1N1

Corzo et al., 2012

H1N2

H1N2v

H3N2

H3...
Current state
• 1. Weaned pigs are a source of
influenza virus
• 2. Infections in growing pigs are highly
prevalent
• 3. I...
Detection of influenza virus in an
all-in/all-out wean-to-finish facility
Percentage positive

Oral fluid and nasal swab r...
Positives

Re infected

99 (75%)

29 (29%)

Positives

Re infected

124 (98%)

102 (82%)
Current state
• 1. Weaned pigs are a source of
influenza virus
• 2. Infections in growing pigs are highly
prevalent
• 3. I...
Sick people can infect pigs
• Multiple reports on human flu strains
infecting pigs
– H1N1 pandemic virus
– H3N2s

• People...
What can producers do?
• 1. Vaccination of influenza
– Improvement of clinical signs but does not
always minimize transmis...
Suckling Piglet Monitoring
At 14
days
of age

100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

Sow vaccination
performed on Fe...
What can producers do?
• 2.Take a “PRRS-like” approach:
– Understand where the viruses come from:
• What’s the source of v...
What can producers do?
• 3. Implement seasonal vaccination of
farm personnel
What works needs to be done?
• 1. Better vaccines and know how to
vaccinate
• 2. Deeper understanding of influenza
transmi...
Conclusions
• Influenza is a very important problem in
pigs
• Control of influenza can be very
frustrating
• Prevention of...
Questions?
torr0033@umn.edu
•
•
•
•
•
•
•
•
•

Seminar Title: PEDV, PRRS and Influenza: Understanding the current state,
future impact and what produc...
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Dr. Montserrat Torremorell - Influenza: Understanding the Current State, Future Impact and What Producers Can Do To Reduce Their Risk

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Influenza: Understanding the Current State, Future Impact and What Producers Can Do To Reduce Their Risk - Dr. Montserrat Torremorell, Allen D. Leman Chair in Swine Health and Productivity Associate Professor, University of Minnesota, from the 2014 Minnesota Pork Congress, January 14-15, Minneapolis, MN, USA.

More presentations at http://www.swinecast.com/2014-minnesota-pork-congress

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  • Two epidemic waves
  • Dr. Montserrat Torremorell - Influenza: Understanding the Current State, Future Impact and What Producers Can Do To Reduce Their Risk

    1. 1. Swine influenza: Current state, future impact and what producers can do to reduce their risk Montse Torremorell, DVM, PhD Leman Chair, University of Minnesota
    2. 2. Introduction • Influenza is a common cause of respiratory disease in pigs • Worldwide distributed • Multiple subtypes and strains within a subtype which difficult the control • Influenza is shared among pigs, poultry and people
    3. 3. UMN VDL 2008-2013 1000 900 800 700 600 500 400 300 200 100 0 Others Untypable H3 / N? H3 / N2 H1 / N? H1 / N2 H1 / N1
    4. 4. Influenza can be costly • Economic impact – $3.23 difference from baseline in loss per head placed (Dykhuis Haden et al., 2012) – $10.41 difference from baseline in loss per head placed due to SIV/PRRSV combination (Dykhuis Haden et al., 2012) – $10.31 ($0.89 ADG, $2.73 FC, $2.94 THI, $3.75 Vet Med) (Donovan 2005)
    5. 5. Current state • 1. Gilts and weaned pigs can be a source of influenza virus Sub-population N Positive Prevalence Gilts < 1 m on-site 625 73 11.7 Gilts > 1 m on-site 1767 37 2.1 Piglets 1796 94 5.2 Total 4188 204 4.9
    6. 6. How important are weaned pigs? Sow farms n=52 44% + Sampling Events n=252 26% + n=2,520 15% + Pools (pools of 3 swabs) Allerson et al., 2013
    7. 7. Sampling event Farm 1 2 3 1 H1 H1 4 Sampling event 5 H1 6 Farm 1 2 3 4 5 H1 H1 H1 6 H1 27 2 28 3 29 4 30 5 H3 H1 H1 31 6 32 7 33 8 34 H1 35 H3 H3 H3 H3 H3 H3 36 H3 H3 H3/H1 H3 H3 H3 37 H1 H1 H1 H1 H1 H1 38 H1 H1 H3 H3 H1 H1 H1 H3 H3 H3 9 H3 H3 H3 10 11 H1 H1 H1 12 13 H1 H1 H3 39 14 40 15 41 16 H3 H3 42 17 43 18 44 H1 45 H3 19 H1 H1 H1 20 46 21 47 22 48 23 49 24 50 H1 H1 51 H1 H1 52 H1 H1 25 26 H1 H1 H1
    8. 8. Farm ID 1 9 11 13 19 25 30 35 36 37 38 40 44 47 50 51 52 Count of HA gene sequences compared Subtype Lowest % identity between all sequences 3 3 2 2 3 2 2 6 6 6 2 2 4 2 2 2 3 H1 H3 H1 H1 H1 H1 H1 H3 H3 H1 H1 H3 H1 H3 H1 H1 H1 99.8 99.7 99.8 99.4 99.5 99.8 99.9 98.8 98.8 99.4 99.9 100 99.8 99.8 99.7 99.9 99.8 • HA gene sequences similar across (+) sampling events within farm • 3 sow herds tested (+) for 6 consecutive sampling events over durations of 156, 165, and 165 days • Different viruses across farms
    9. 9. Current state • 1. Weaned pigs are a source of influenza virus • 2. Infections in growing pigs are highly prevalent
    10. 10. Current state • 2. Infections in growing pigs are highly prevalent 32 farms tested monthly for 2 years (Jun 2009-Dec 2011) 16,170 nasal swabs 746 (4.6%) tested positive Corzo et al., 2012
    11. 11. Epidemiology Grow-finish surveillance Corzo et al., 2012
    12. 12. Farm Identification Number Genetic diversity in grow-finish sites H1N1 pH1N1 Corzo et al., 2012 H1N2 H1N2v H3N2 H3N2v Untypable Mixed Infection
    13. 13. Current state • 1. Weaned pigs are a source of influenza virus • 2. Infections in growing pigs are highly prevalent • 3. Infections in groups of pigs can be prolonged
    14. 14. Detection of influenza virus in an all-in/all-out wean-to-finish facility Percentage positive Oral fluid and nasal swab results 100 80 60 Nasal swabs 40 Oral fluids 20 0 0 9 16 26 35 47 58 69 79 96 Day of study Weaned pigs are an important source for virus movement Prolonged detection of infection in growing pig populations
    15. 15. Positives Re infected 99 (75%) 29 (29%) Positives Re infected 124 (98%) 102 (82%)
    16. 16. Current state • 1. Weaned pigs are a source of influenza virus • 2. Infections in growing pigs are highly prevalent • 3. Infections in groups of pigs can be prolonged • 4. People can be a source of new viruses into pigs
    17. 17. Sick people can infect pigs • Multiple reports on human flu strains infecting pigs – H1N1 pandemic virus – H3N2s • People contribute to the influenza genetic diversity found in pigs • Not all strains transmitted equally
    18. 18. What can producers do? • 1. Vaccination of influenza – Improvement of clinical signs but does not always minimize transmission – Sow vaccination • Pre-farrowing vaccination • Whole herd mass vaccination – Interference with maternal immunity
    19. 19. Suckling Piglet Monitoring At 14 days of age 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Sow vaccination performed on Feb11 and Mar 11-14 21-Feb 22-Mar 6-Apr 25-Apr 10-May 25-May 14 days At 21 days of age 10-Mar 14 days 14 days 14 days 14 days 14 days 14 days Negative 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Suspect Positive CT value: 37.99 1 pig 21-Feb 10-Mar 22-Mar 6-Apr 25-Apr 10-May 25-May 21 days 21 days 21 days 21 days 21 days 21 days 21 days Negative Suspect Positive
    20. 20. What can producers do? • 2.Take a “PRRS-like” approach: – Understand where the viruses come from: • What’s the source of virus? • Weaned or replacement animals or people or air? – Start at the top – Assess whether/how different practices/strategies work: • • • • Vaccination – how should we vaccinate populations? Herd closure Early weaning Others?
    21. 21. What can producers do? • 3. Implement seasonal vaccination of farm personnel
    22. 22. What works needs to be done? • 1. Better vaccines and know how to vaccinate • 2. Deeper understanding of influenza transmission and epidemiology • 3. Assess biosecurity programs to minimize introduction of new viruses and mitigate existing ones
    23. 23. Conclusions • Influenza is a very important problem in pigs • Control of influenza can be very frustrating • Prevention of new infections should be a priority
    24. 24. Questions? torr0033@umn.edu
    25. 25. • • • • • • • • • Seminar Title: PEDV, PRRS and Influenza: Understanding the current state, future impact and what producers can do to reduce their risk. Presenters: Dr. Lisa Becton, National Pork Board [PEDV] – Dr. Montserrat Torremorell, U of MN [Influenza] – Dr. Dave Wright, Veterinarian [PRRS] Seminar Format: Each presenter will have up to 15 minutes to discuss the most up-to-date information about their area of focus. Topics of discussion should include, but are not limited to, 1. What is the current state of the health challenge in MN / nationally? 2. What new developments have been made to control the health challenge? 3. What can producers do to reduce their risk of exposure on their farms? 4. What work still needs to be done?

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