PRRS season is almost upon us. Across the United States, the months of October, November, and December see the largest increases in cases. We don’t know exactly why, but there is speculation that it may have something to do with weather conditions changing in the fall, allowing the virus to remain in an aerosol form. Humidity, cloudiness, slow-moving winds, and cool temperatures are all associated with an uptick in PRRS infections.

Harvest may also have something to do with the increase in PRRS cases. During this time of year, there is so much activity in the field that leads to a lot of dust in the air, and the virus may attach to these dust particles. However, we haven’t really studied this as a potential risk factor.

Pumping pits containing slurry from infected populations and applying it on our fields may also be related to the spread of the PRRS virus.

Managing the increase
In any case, there are three things we can do to keep the number of PRRS cases at a minimum during the fall.

1. Maintain a high level of biosecurity. Dr. Joel Nerem and our biosecurity group have implemented a rigorous plan across the system. This plan includes washing vehicles, showering into our farms, and following strict supply entry protocols—all things we know that, if practiced diligently, will reduce PRRS infection rates.
2. Vaccinate grow-finish pigs. Work done by Pipestone Applied Research tells us we can reduce spread of PRRS from farm to farm by vaccinating grow-finish pigs (especially those near sow farms) with a modified live PRRS vaccine. Besides reducing viral shedding by these pigs, recent research tells us that vaccinated pigs grow faster and do better than unvaccinated pigs, so vaccination is good for the neighborhood and good for the individual farm.
3. Filter sow barns. Pipestone Management has been filtering sow barns for about five years. More than 50% of our barns are filtered—the most in the entire industry. To reduce the risk of airborne transfer of the PRRS virus, Pipestone Management has also partnered with The 3M Company on a filter that improves airflow, catches more virus, and is more durable. We’ve begun installing these filters when the lifespan of our current filters runs out. These filters cost less than the previous filters, so air filtration is becoming more cost-effective.

Talk with your herd veterinarian, review your biosecurity protocols, discuss vaccination, and, if you filter, discuss the 3M option. If you do not filter, the idea of filtration is something you should seriously consider as we enter this season of higher PRRS infection.