Mycoplasmal pneumonia in Swine

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. 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-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

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. 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