Seneca-Associated Diseases, Clinical Presentation And Epidemiological Distribution - Dr. Daniel Linhares, from the 2015 Allen D. Leman Swine Conference, September 19-22, 2015, St. Paul, Minnesota, USA. More presentations at http://www.swinecast.com/2015-leman-swine-conference-material

1. Seneca-Associated Diseases:
Clinical Presentation and
Epidemiological Distribution
Daniel Linhares1, Chris Rademacher1,
Fabio Vannucci2, David Barcellos3
1Iowa State University, 2University of Minnesota,
3Universidade Federal do Rio Grande do Sul

2. Acknowledgements
• US team – Drs Rademacher, Yoon, (JQ)
Jianqiang, Zimmerman, Gauger, Derscheid,
Pineyro, Schwartz, Bates, Canon, Canning,
Karriker, Holtkamp, Baum, Madson, Arruda,
Maine, Halbur
• Brazil team – Drs Barcellos, Paladino, Guedes,
Rosa, Assayag, Heck, Zanella, dos Santos, Reis
• Funding:

3. Brazilian outbreak
and
Vesicles
Foot
Neonatal losses

4. Definition of ETNL
E
Epidemic
Sudden
onset, up to
70%
T
Transient
Self-limiting
(7-10 days)
NL
Neonatal
Losses
<3 and <7
days old
Vannucci et al., 2015

5. Timeline
"shift" from ETNL to IVD
Timeline of onset of Epidemic Transient Neonatal Losses (ETNL) and
Idiopathic Vesicular Disease (IVD) in Brazil
Linhares, Barcellos, Vannucci 2015 (in prep)
 We estimate that 70-80% of Brazilian
swine industry has experienced ETNL
or IVD
 We are not aware of re-breaks
 Mortality on ETLN cases took 4-10
days to return to baseline
 Pigs affected with DVI healed lesions
in 10-15 days

6. US outbreak
~same clinical pictures…

7. Seneca & US…
• Circulating since 1988 (USDA data)
• Summer 2015: increase in number of reports
– IA, MN, IL, SD, MO
– Exhibit pig cases (8 fairs)
– Finishing sites (~15 cases)
– Sow farms (~40 cases)
• Retrospective sampling (UMN, ISU, NC):
– Low prevalence of Seneca RNA detection by
PCR

8. Vesicular disease: snouts and/or foot, variable lesion prevalence: sows vs nursery vs finishers

9. Most cases:
Minor/mild,
“few days”
snout lesions.

10. VD lesions: transient, healing ~ 1-2 weeks, shedding, +2-3 weeks*
*Rademacher et al., 2015

11. Epidemic transient neonatal mortality
4-10 days (duration)
neonatal
5-6h

12. Epidemic transient neonatal mortality
VD in sows: varies, low prevalence? Minor? Subclinical?

13. Epidemic transient neonatal mortality
Most piglets had stomachs full of milk, lethargic
~50% cases: piglet diarrhea (mesocolonic edema)
~70% cases: reported VD in sows
Linhares & Teixeira, 2015 in prep
No apparent reproductive impact on sows

14. Sampling…
• Finishing pigs
– Clinical signs (lameness, VD lesions)
– (#1) Swab lesions, (#2) Oral fluids, also nasal
rectal, and/or tonsil swabs, serum (transient
viremia)
• Sow farms
– Clinical signs (sudden increase in neonatal
mortality, VD-like lesions)
– (#1) Swab lesions, (#2) piglet nasal/rectal
swabs

15. Summary
• Vesicular disease
– High morbidity (> 50%)
– ~Zero mortality
– Healing/recovery ~ 2 weeks
– Still shedding additional 2-3 weeks
– Key: communication with health officials/power plant
• Epidemic Transient Neonatal Losses
– High morbidity within litters (>70% farrowing)
– High mortality (up to 70% young litters: 1-4 days age)
• Litters with 0-1 days old: high mortality.
• Litters 5+ days old: not clinically affected
– Back to baseline mortality: 4-10 days
– Do piglets w/o clinical signs carry virus? yes

16. Thoughts
• SVV
– Consistency on association with VD
– ETNL?: most cases with VD, also SVV by PCR
– If SVV is causing, which SVV? Alone or with
something else? If something else, infectious?
• Assuming infectious agent (SVV, or SVV+?)
– Highly transmissible
– Highly immunogenic
– Quick establishment of protective, long lasting
immunity
– If Seneca, has it changed? How to define new vs old
(markers)?

17. Thoughts on transmission
(assuming Seneca  Disease)
• Extremely high transmission rate
– Quick onset, quick natural “whole herd”
exposure??
• Highly immunogenic, long lasting immunity
– After 7 days: infection is gone
– No rebreaks after ~10 months (BR experience)
• Easily transmitted indirectly (air? mosquitoes?
other animals, truck, feed ingredients, vaccines?)
– BR experience: clustered time & space

18. Moving forward…
• Sow farm and growing pig longitudinal shedding studies
• Infection models: understand dynamics of infection,
seroconversion and immunity
• Koch’s postulates (assess Seneca’s role on both clinical
syndromes)
• Dx tools & Epidemiological studies (molecular
comparisons, looking for virus & antibodies in the swine
industry, finding triggers of vesicular disease/neonatal
mortality syndromes)

19. Daniel Linhares, DVM, MBA, PhD
Assistant Professor, Dept of Vet Diagn & Production Animal Medicine
Director of Graduate Education
Iowa State University College of Veterinary Medicine
Office: (515) 294-9358
Mobile: (515) 357-1044
Linhares@IAstate.edu
http://field-prrs.blogspot.com/
Google:
(ISU) James McKean Swine Disease Conference
Thursday, November 5 - Friday, November 6, 2015. Ames, IA.
Thank you very much!