PRRS Declines Overall But Increases in Certain Regions

The Swine Health Information Center reports the number of PRRS cases continued to decline across the U.S. overall during August but increased in some regions.
As part of its September enewsletter the Swine Health Information Center has released its domestic and global swine disease surveillance reports.

SHIC Associate Director Dr. Megan Niederwerder says domestically we did see a reduction in the percent of PRRS positive cases detected overall in August compared to July, which is good news however there continues to be regional increases in Nebraska, Missouri and Indiana.

Clip-Dr. Megan Niederwerder-Swine Health Information Center:

There's been an increase in the detection of lineage 1C 124 across the U.S. and many of the highest pork producing states are continuing to monitor that lineage 1C that's been detected and are working with the producer and veterinarian advisory group to understand the clinical relevance and importance of that specific lineage strain.

I think it goes back to the importance, particularly for those states that continue to see regional increases, to understand what's circulating, what's potentially the best vaccine option for the strain that is circulating in your herd, what's the divergence of the strain in your herd compared to either herds in your state or throughout the U.S. or throughout the world and really keeping an eye on the genetic divergence of PRRS virus that is circulating in your herd.

Dr. Niederwerder says different lineages have different characteristics with regards to pathogenesis so perhaps they would have either increased or decreased clinical signs, severity of symptoms in certain age groups, they’d be more stable in the environment or have different transmission rates.She notes PRRS is a virus with one of the highest mutation rates.