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

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:

Brazilian outbreak

and

Vesicles

Foot

Neonatal losses

Definition of ETNL

E

Epidemic

Suddenonset, up to

70%

T

Transient

Self-limiting (7-10 days)

NL

Neonatal Losses

<3 and <7 days old

Vannucci et al., 2015

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

US outbreak

~same clinical pictures…

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

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

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

VD lesions: transient, healing ~ 1-2 weeks, shedding, +2-3 weeks*

*Rademacher et al., 2015

Epidemic transient neonatal mortality

4-10 days (duration)

neonatal

5-6h

Epidemic transient neonatal mortality

VD in sows: varies, low prevalence? Minor? Subclinical?

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

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

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

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)?

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

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)

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!