Impacts of Influenza virus in Danish swine herds
30-01-2018 CPH Pig seminar
DVM, Ph.d student Pia Ryt-Hansen
17/04/2008 Presentation name 2 DTU Vet, Technical University of Denmark
Background:
• Influenza A virus (IAV) is enzootic in swine herds globally
• Important co-factor in the Porcine Respiratory Disease Complex
• Leads to clinical signs of respiratory disease
• Increases the incidence of secondary diseases
• Recent studies:
– Persistence of IAV within the herd
– Questionable effect of maternal IAV antibodies from vaccinated sow
• Zoonotic potential
Denmark:
• 90 % of all sows from 150 herds had IAV antibodies
• 45 % of all diagnostics respiratory samples are IAV positive
– More subtypes in the same herd
– Herds test IAV positive continuously
– More attention to IAV as a major pathogen
– Vaccine sales have increased 350 % since 2010
17/04/2008 Presentation name 3 DTU Vet, Technical University of Denmark
Aim:
H1N1 H1N1pdm H3N2
H1N2
?
17/04/2008 Presentation name 4 DTU Vet, Technical University of Denmark
Aim:
17/04/2008 Presentation name 5 DTU Vet, Technical University of Denmark
Aim:
17/04/2008 Presentation name 6 DTU Vet, Technical University of Denmark
Aim:
17/04/2008 Presentation name 7 DTU Vet, Technical University of Denmark
Study design
2 weeks before farrowing
Week 1 Week 3 Week 5 Week 10-12
Sows: Blood sample Nasal swab
Offspring: Nasal swab Blood sample + Nasal swab
Nasal swab Blood sample + Nasal swab
17/04/2008 Presentation name 8 DTU Vet, Technical University of Denmark
Herds
Exclusion criteria:
• No SIV vaccination for minimum 1 year
• Cannot start up vaccination during the study
Inclusion criteria:
• Minimum 300 sows
• Production from 0-12 weeks of age
• Weekly production
• History of respiratory disease or laboratory confirmation of SIV
17/04/2008 Presentation name 9 DTU Vet, Technical University of Denmark
Herds
Herd 1: H1N2
• Non SPF
Herd 2: H1pdmN1pdm
• Blue SPF
Herd 3: H1N1av/H1N2
• Blue SPF + AP2 + Type 1
Herd 4: H1N2
• Blue SPF
1
2 3 4
17/04/2008 Presentation name 10 DTU Vet, Technical University of Denmark
Discussion: Endemically infected herds: Herd 1, 2 and 4
– Early infection - 3 days old piglets
– Infection in all sections
– Sow as a source of viral shedding in the farrowing unit
– Low level of persistent IAV shedders
– Infected piglets from IAV antibody positive sows – questionable effect of maternal antibodies:
• 98 % of all pigs becomes infected before week 8
– Vaccine efficacy?
» Future studies
17/04/2008 Presentation name 11 DTU Vet, Technical University of Denmark
Discussion: Acute outbreak with a new subtype in Herd 3
– Changed dynamics
– Infection limited to the farrowing unit – week one
– Large diversity of the HA gene within the same HA subtype
• Viral escape
• No protection of the piglets
– Vaccine efficacy?
» Future studies
– Internal biosecurity
• Limit movement of pigs
• All in all out
• No weaned piglets in the farrowing unit
• Sectioning of age groups
• No back-flow of pigs or personnel
• Vaccination of personal
• Quarantine
17/04/2008 Presentation name 12 DTU Vet, Technical University of Denmark
Acknowledgements: • DTU vet:
– Lars Erik Larsen
– Jesper Schak Krog
– Hue Thi Tranh Tran
– Nina Dam Grønnegaard
– Tine Skotte Hammer
• IDT Biologika:
– Inge Larsen
– Anja Kibsgaard
– Jens Dam
– Silke Wacheck
• SEGES Svineproduktion:
– Charlotte Sonne Kristensen
– Lotte Skade
– Kirsten Pihl
– Jane Rasmussen
• Besætninger:
– Ejere og medarbejdere (anonyme)
• Dyrlæger:
– Anders Elvstrøm
– Sten Larsen
– Gerben Hoornenborg
17/04/2008 Presentation name 13 DTU Vet, Technical University of Denmark
Questions?