ABCD

Mycoplasmal pneumonia in Swine

Immunologic Considerations

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ABCDMycoplasmal 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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ABCDThe “customer”

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ABCDWhat is “success”?

• Final customer…the pig• Welfare & well being

• Producer• Biology financial

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ABCDMaes, et al

• Typical economic impact

ADG, Cull

Mortality

• FE

Vaccine, 1999

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ABCDStudy designs

• Random, blinded evaluations• block by source, sex, weight, etc

• Four weeks from vaccination to challenge

• Four week monitoring period

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ABCDImmunity

• 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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ABCDCellular Immunity

• Dr. E Thacker• Various levels of cellular immune

response

• Sensitized via vaccination

• All vaccines protected lungs

Swine Health & Production

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ABCDCMI Relationship

• CMI = Cell mediated immunity

• Peripheral lymphocytes

• Association with growth rate?• Higher CMI level at challenge• Higher ADG

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ABCDClinical study

• Higher CMI responses associated with• Higher Average Daily Gain

• Reduced Lung lesions

• Replication of results

Roof, AASV 2001

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ABCDCombination control

• Application of vaccines & therapeutics

• “Complimentary” strategies?

• Sources of active immunity• Immunization• Field organism exposure

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ABCDNatural exposure

• Slow onset in continuous production systems• Low level introduction/late spread

• Aerosol spread & dose

• Alone or complicated disease

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ABCDLinkage

• Several methods to develop immunity

• Prior to vaccines…• Strategic medications one week per

month

• Study case

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ABCDProphylaxis & Metaphylaxis• Established clinical disease

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

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ABCDMetaphylaxis

• 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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ABCDMetaphylaxis

• Limited duration of therapeutic medication:

• Advantages• limits cost• organism/antibiotic exposure time• development of resistance

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ABCD

• 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 for Metaphylactic Strategic-Dosing

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ABCDPotential

• Change in epidemiology• Timing of vaccination prior to exposure• Newly diagnosed disease

• Multiple disease challenges require broad spectrum intervention tool

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ABCDCase 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)

ADGF/GADFI

• Inconsistent diagnostic findings

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ABCDDesign

• 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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ABCDTherapeutic 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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ABCDOutcomes

• 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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ABCDImpact on Mycoplasma

MYCOPLASMA serology

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0 2 4 6 8 10 12 14 16

Week

Tw

ee

n 2

0 O

D

Continuous Med Mhyo

Pulse Med Mhyo

Control Mhyo

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ABCDImmunology

• 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

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ABCDImplications

• Therapeutic use of medications or biologics

• Goals of model• Growth• Lungs

• Defined vs. natural exposure• Immunity

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ABCDEnd 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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ABCDSummary thoughts

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

• Limitations• Incomplete control...

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ABCDCombined approaches

• May enhance control of Mycoplasmal disease

• Improved total respiratory health

• “Enhance” active immunity

• Limit biologic consequences of exposure