Dr. Daniel Linhares - Seneca-Associated Diseases, Clinical Presentation And Epidemiological...

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  • 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


  • Brazilian outbreak




    Neonatal losses

  • Definition of ETNL



    Suddenonset, up to




    Self-limiting (7-10 days)


    Neonatal Losses

  • 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


  • 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)



  • 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


    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

    Kochs postulates (assess Senecas role on both clinical


    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, PhDAssistant 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



    Google:(ISU) James McKean Swine Disease Conference

    Thursday, November 5 - Friday, November 6, 2015. Ames, IA.

    Thank you very much!