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”

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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 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

Impact on Mycoplasma

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

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

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