Mycoplasmal pneumonia in swine
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Mycoplasmal pneumonia in Swine. Immunologic Considerations. Mycoplasmal pneumonia. Chronic infection of ciliated epithelium Increased cost Interventions, fixed cost Reduce revenue Reduced growth rate (# sold) Cull/substandard pigs (price penalty) Mortality. The “customer”.

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Mycoplasmal pneumonia in swine

Mycoplasmal pneumonia in Swine

Immunologic Considerations


Mycoplasmal pneumonia
Mycoplasmal pneumonia

  • Chronic infection of ciliated epithelium

  • Increased cost

    • Interventions, fixed cost

  • Reduce revenue

    • Reduced growth rate (# sold)

    • Cull/substandard pigs (price penalty)

    • Mortality



What is success
What is “success”?

  • Final customer…the pig

    • Welfare & well being

  • Producer

    • Biology  financial


Maes et al
Maes, et al

  • Typical economic impact

  •  ADG,  Cull

  •  Mortality

  • FE

Vaccine, 1999


Study designs
Study designs

  • Random, blinded evaluations

    • block by source, sex, weight, etc

  • Four weeks from vaccination to challenge

  • Four week monitoring period


Immunity
Immunity

  • Passive Immunity

    • Protects from challenge

    • May interact with active immunization

  • Active Immunity

    • Level/duration of protection

  • Thacker,et al 2000; BIVI 2000


Cellular immunity
Cellular Immunity

  • Dr. E Thacker

    • Various levels of cellular immune response

    • Sensitized via vaccination

    • All vaccines protected lungs

Swine Health & Production


Cmi relationship
CMI Relationship

  • CMI = Cell mediated immunity

  • Peripheral lymphocytes

  • Association with growth rate?

    • Higher CMI level at challenge

    • Higher ADG


Clinical study
Clinical study

  • Higher CMI responses associated with

    • Higher Average Daily Gain

    • Reduced Lung lesions

  • Replication of results

Roof, AASV 2001


Combination control
Combination control

  • Application of vaccines & therapeutics

  • “Complimentary” strategies?

  • Sources of active immunity

    • Immunization

    • Field organism exposure


Natural exposure
Natural exposure

  • Slow onset in continuous production systems

    • Low level introduction/late spread

  • Aerosol spread & dose

  • Alone or complicated disease


Linkage
Linkage

  • Several methods to develop immunity

  • Prior to vaccines…

    • Strategic medications one week per month

  • Study case


Prophylaxis metaphylaxis
Prophylaxis & Metaphylaxis

  • Established clinical disease

  • “Peri” outbreak

    • Little or no overt clinical disease

    • Exposure has occurred

    • “Incubation” period


Metaphylaxis
Metaphylaxis

  • Metaphylaxis: e.g. Strategic-Dosing

  • natural exposure allows infection and incubation immediately prior to short-termmedicationto shut down the incubation process prior to expression of disease and associated negative biologic and economic consequences

  • Exposure may aid development of protective long-termactive immunity against endemic diseases


Metaphylaxis1
Metaphylaxis

  • Limited duration of therapeutic medication:

  • Advantages

    • limits cost

    • organism/antibiotic exposure time

    • development of resistance


Potential for metaphylactic strategic dosing
Potential for Metaphylactic Strategic-Dosing

  • Inability to exclude infection

    • Disease outbreaks later in production

      • SEW/18-week wall, etc

      • Lawsonia/PPE

  • Vaccines not available or only partially effective

    • APP

    • Streptococcus

    • Compliance failure


Potential
Potential

  • Change in epidemiology

    • Timing of vaccination prior to exposure

    • Newly diagnosed disease

  • Multiple disease challenges require broad spectrum intervention tool


Case study
Case study

  • Commercial 3-site production system in Midwest

  • Consistent history of decreased performance 8-12 weeks post-placement in finisher (18-22 weeks of age)

    • ADG

    • F/G

    • ADFI

  • Inconsistent diagnostic findings


  • Design
    Design

    • 2 animals per pen were serially bled every two weeks

    • Serology was initially performed on placement and closeout samples to screen for M. hyo, PRRS, SIV, TGE, Salmonella and Lawsonia activity

    • Additional serology was performed on bi-weekly samples for pathogens shown to be active in finishing based on screening serology

    Swine Health & Production, 2000


    Therapeutic options
    Therapeutic options

    • Treatment 1: Denagard +Aureomycin pulsed 5 times (2, 4, 7, 10, and 13 weeks post-placement) and Aureomycin 100g/t given weeks 3, 5, 6, 8, 9, 11, and 12 [“Continuous”]

    • Treatment 2: Denagard(35 g/t) + Aureomycin(10 mg/lb BW) pulsed 5 times (2, 4, 7, 10, and 13 weeks post-placement) [“Pulse”]

    • Treatment 3: Non-medicated Controls


    Outcomes
    Outcomes

    • Consistently observed performance  did not occur during any 2-week interval

    • Perhaps because 2/3 of the animals in the barn/airspace were on systemic antibiotics which  infection pressure

    • However both med strategies significantly improved overall survivability and performance



    Immunology
    Immunology

    • Both strategic and continuous medication strategies significantly improved ADFI, ADG, F/G and survivability while being cost-effective

    • There were no significant performance differences between strategic and continuous medication strategies

    • Strategic medication permitted natural Mycoplasma exposure and immune response (seroconversion) as w/ NMC’s while improving/protecting growth performance


    Implications
    Implications

    • Therapeutic use of medications or biologics

    • Goals of model

      • Growth

      • Lungs

        • Defined vs. natural exposure

      • Immunity


    End consumers
    End consumers

    • The pig

      • Reduced clinical disease

      • Maintenance of therapeutic application & use

      • Welfare

    • Consumer

      • Reduced medication use

        • Residue, resistance

      • More efficient resource use


    Summary thoughts
    Summary thoughts

    • Immunologic advantages in Mycoplasma control

      • Single point application

      • Defined investment

      • Limited residue/resistance

    • Limitations

      • Incomplete control...


    Combined approaches
    Combined approaches

    • May enhance control of Mycoplasmal disease

      • Improved total respiratory health

      • “Enhance” active immunity

      • Limit biologic consequences of exposure


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