Management & Control
The goal of any PRRS program is to maximize immunity and minimize transmission, all while optimizing profits. PRRS management requires a systematic whole-herd approach that includes:
- Evaluating options for building immunity in your breeding herd and/or growing pigs
- Developing and implementing protocols to minimize transmission
- Applying the strictest possible biosecurity protocols to reduce introduction and/or circulation of the virus within the herd or site
Building ImmunityWhen building immunity for PRRS, it’s important to develop a plan that protects the whole herd – including both the breeding herd (sows, replacement gilts) and growing pigs – seeking to attain and maintain uniform population immunity. You have several immunity tools available:
Killed Virus Vaccine
- Vaccine virus is inactivated
- There is currently no science-based evidence that a killed PRRS vaccine demonstrates effective protection1
- Primary use in the industry is as a booster, following modified-live virus (MLV) vaccination, but there is no evidence supporting the effectiveness of this protocol
- Autogenous vaccines are developed for a particular farm, utilizing virus samples from a specific operation
- These vaccines do not have to demonstrate effectiveness; they only have to demonstrate safety
1 Roof M. Compilation of experimental investigations of PRRS vaccine technologies using modified live vaccines, inactivated vaccines and immunomodulation. Allen D. Leman Swine Conference, St. Paul, Minn. 2008;30–40.
Live Virus Innoculation (LVI)
- Use of farm-specific live virulent PRRS virus to establish uniform population exposure and subsequent immunity
- Primarily used in load-close-expose protocols to establish breeding-herd stability following a PRRS break
- Can create clinical disease, as well as perpetuate/promote ongoing circulation and genetic mutation of the PRRS virus
- The industry trend is to move away from LVI protocols
Modified-Live Virus (MLV) Vaccine
Additional information about developing an immunity management plan – in combination with biosecurity – can be found in the “Construct Solution Options” section of the SOURCE model.
- Vaccine virus is altered to induce an immune response without causing clinical disease
- Well-documented evidence shows effective protection against multiple strains of PRRS virus to protect breeding herds and growing pigs
- Used in protocols targeted at attaining and maintaining uniform population immunity with population-based protocols. Examples include:
- Mass vaccination protocols (quarterly or seasonally) to reach breeding-herd stability
- Vaccination of growing pigs at weaning
A complete and effective swine production operation biosecurity plan to manage PRRS and other swine diseases requires actions in all aspects of swine production. For a better understanding of biosecurity risks within your operation, complete the “Understanding Risks” assessment, and work with your herd veterinarian to reduce these risks.
Basic biosecurity principles for mitigating PRRS include:
- Sanitation/Hygiene – Cleaning and disinfection
- Exclusion – Keep whatever is transmitting the virus (e.g., surface, pest, pig) out
- Separation – Dedicate things to only one purpose (e.g., dedicated trailers)
Day-to-day management will have the greatest impact on biosecurity implementation and success. Focus on critical control points as non-negotiable and verify the process with all team members for implementation and practicality.
Additional information about biosecurity and reducing the risk of virus introduction can be found in the “Reduce Risks” section of the SOURCE model.