Farmscape for June 20, 2022

The Swine Health Information Center is advising additional monitoring and stepped-up biosecurity in those states that experienced an increase in Porcine Reproductive and Respiratory Syndrome.
The Swine Health Information Center's Domestic Swine Disease Monitoring Report for June indicates the overall detection of PRRS declined in May and was within expectations, with the exception of Nebraska, Illinois, Indiana and Missouri which saw regional increases.
SHIC Associate Director Dr. Megan Niederwerder says the introduction of new PRRS lineages, specifically the 1-C variant into Nebraska and Missouri, may be what is contributing to this increase at the regional level.

Clip-Dr. Megan Niederwerder-Swine Health Information Center:
When we see these regional increases and they are associated back to a new introduction of a PRRS lineage that perhaps the herds have not seen before so they are naive to these new PRRS lineages we can see, without that underlying immunity that's directed towards some of these new lineages, the pigs may replicate the virus to higher levels, they may have more production effects from PRRS virus even if they had an underlying immunity to a previous PRRS virus.
With any new lineage we see that the pigs are often times more susceptible to those high virus levels as well as disease associated with the virus.
Of course, when there's increased disease as well as increased virus replication there's an increased risk of regional spread.
We have seen that in those specific states, again associated with that new lineage 1-C variant.

Dr. Niederwerder says the expectation is that PRRS will continue to decline but, in those states that have seen regional increases, continued monitoring of herds for any increase in PRRS associated clinical signs and continued diagnostics will be necessary to be sure of which strain is circulating.
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Bruce Cochrane.

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