PRRS Corner: PRRS Incidence Study Update

The 2013-2014 PRRS epidemic season continues to be surprisingly different. Using previous four years as a baseline for expected number of breaks, we have observed significantly fewer cumulative new breaks thru December (p = 0.0002). When we look at this on a quarterly basis, we have seen fewer breaks from July to September (p = 0.0139) and from October to December (0.0049). It is interesting because the differences between the years appears to have started back in the summer months. Click here to view the most recent graphs.

Several reasons have been proposed to explain this:Random chance - Better awareness of PRRS epidemic seasons leading to better bio-security preparations

  • Difficulty identifying PRRS infections in herds co-infected with PED
  • Reduced PRRS diagnostics during PED outbreaks
  • Shorter duration of PRRS positive pig production during PED breaks
  • Extremely cold weather conditions across much of the mid-west
  • Next virulent strain of PRRS has not yet arrived