1. Mycoplasmal pneumonia in Swine
Immunologic Considerations

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

3. The “customer”

4. What is “success”? Final customer…the pig Welfare & well being
Producer
Biology  financial

5. Maes, et al Typical economic impact  ADG,  Cull  Mortality FE
Vaccine, 1999

6. Study designs Random, blinded evaluations
block by source, sex, weight, etc
Four weeks from vaccination to challenge
Four week monitoring period

7. Immunity Passive Immunity Protects from challenge
May interact with active immunization
Active Immunity
Level/duration of protection
Thacker,et al 2000; BIVI 2000

8. Swine Health & Production
Cellular Immunity
Dr. E Thacker
Various levels of cellular immune response
Sensitized via vaccination
All vaccines protected lungs
Swine Health & Production

9. CMI Relationship CMI = Cell mediated immunity Peripheral lymphocytes
Association with growth rate?
Higher CMI level at challenge
Higher ADG

10. Clinical study Higher CMI responses associated with
Higher Average Daily Gain
Reduced Lung lesions
Replication of results
Roof, AASV 2001

11. Combination control Application of vaccines & therapeutics
“Complimentary” strategies?
Sources of active immunity
Immunization
Field organism exposure

12. Natural exposure Slow onset in continuous production systems
Low level introduction/late spread
Aerosol spread & dose
Alone or complicated disease

13. Linkage Several methods to develop immunity Prior to vaccines…
Strategic medications one week per month
Study case

14. Prophylaxis & Metaphylaxis
Established clinical disease
“Peri” outbreak
Little or no overt clinical disease
Exposure has occurred
“Incubation” period

15. 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

16. Metaphylaxis Limited duration of therapeutic medication: Advantages
limits cost
organism/antibiotic exposure time
development of resistance

17. 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

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

19. 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

20. Swine Health & Production, 2000
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

21. 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

22. 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

23. Impact on Mycoplasma

24. 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

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

26. End consumers The pig Reduced clinical disease
Maintenance of therapeutic application & use
Welfare
Consumer
Reduced medication use
Residue, resistance
More efficient resource use

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

28. Combined approaches May enhance control of Mycoplasmal disease
Improved total respiratory health
“Enhance” active immunity
Limit biologic consequences of exposure