Mycoplasmal pneumonia in Swine

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Mycoplasmal pneumonia in Swine

• Immunologic Considerations

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Mycoplasmal pneumonia

• Chronic infection of ciliated epithelium
• Increased cost
• Interventions, fixed cost
• Reduce revenue
• Reduced growth rate ( sold)
• Cull/substandard pigs (price penalty)
• Mortality

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The customer
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What is success?

• Final customerthe pig
• Welfare well being
• Producer
• Biology ? financial

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Maes, et al

• Typical economic impact
• ? ADG, ? Cull
• ? Mortality
• FE

Vaccine, 1999
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Study designs

• Random, blinded evaluations
• block by source, sex, weight, etc
• Four weeks from vaccination to challenge
• Four week monitoring period

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Immunity

• Passive Immunity
• Protects from challenge
• May interact with active immunization
• Active Immunity
• Level/duration of protection

Thacker,et al 2000 BIVI 2000
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Cellular Immunity

• Dr. E Thacker
• Various levels of cellular immune response
• Sensitized via vaccination
• All vaccines protected lungs

Swine Health Production
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CMI Relationship

• CMI Cell mediated immunity
• Peripheral lymphocytes
• Association with growth rate?
• Higher CMI level at challenge
• Higher ADG

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Clinical study

• Higher CMI responses associated with
• Higher Average Daily Gain
• Reduced Lung lesions
• Replication of results

Roof, AASV 2001
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Combination control

• Application of vaccines therapeutics
• Complimentary strategies?
• Sources of active immunity
• Immunization
• Field organism exposure

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Natural exposure

• Slow onset in continuous production systems
• Low level introduction/late spread
• Aerosol spread dose
• Alone or complicated disease

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Linkage

• Several methods to develop immunity
• Prior to vaccines
• Strategic medications one week per month
• Study case

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Prophylaxis Metaphylaxis

• Established clinical disease
• Peri outbreak
• Little or no overt clinical disease
• Exposure has occurred
• Incubation period

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Metaphylaxis

• Metaphylaxis e.g. Strategic-Dosing
• natural exposure allows infection and incubation
  immediately prior to short-term medication to
  shut down the incubation process prior to
  expression of disease and associated negative
  biologic and economic consequences
• Exposure may aid development of protective
  long-term active immunity against endemic
  diseases

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Metaphylaxis

• Limited duration of therapeutic medication
• Advantages
• limits cost
• organism/antibiotic exposure time
• development of resistance

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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

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Potential

• Change in epidemiology
• Timing of vaccination prior to exposure
• Newly diagnosed disease
• Multiple disease challenges require broad
  spectrum intervention tool

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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

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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
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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

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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

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Impact on Mycoplasma
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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/ NMCs while improving/protecting growth
  performance

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Implications

• Therapeutic use of medications or biologics
• Goals of model
• Growth
• Lungs
• Defined vs. natural exposure
• Immunity

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End consumers

• The pig
• Reduced clinical disease
• Maintenance of therapeutic application use
• Welfare
• Consumer
• Reduced medication use
• Residue, resistance
• More efficient resource use

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Summary thoughts

• Immunologic advantages in Mycoplasma control
• Single point application
• Defined investment
• Limited residue/resistance
• Limitations
• Incomplete control...

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Combined approaches

• May enhance control of Mycoplasmal disease
• Improved total respiratory health
• Enhance active immunity
• Limit biologic consequences of exposure