The Swine Health Information Center (SHIC) has announced that the PRRS-2 Lineage 1C.5 Clonally Expanded Clade has become the dominant Porcine Reproductive and Respiratory Syndrome (PRRS) lineage circulating in the United States. Since its emergence in 2020, this lineage has now spread to eight states, with a significant increase in cases reported in early 2024.
Rising Cases and Spread Across States
Dr. Megan Niederwerder, Executive Director of SHIC, reports that between July 2023 and December 2024, there were 945 documented cases of PRRS viruses with sequences matching this clade. “The high genetic similarity among these viruses indicates a significant increase in distribution of the L1C.5 virus clade,” she explained.
The initial index case was identified in the summer of 2023 on a grow-finish farm in Iowa. Since then, the virus has rapidly spread beyond Iowa to other states, including Minnesota, Illinois, Missouri, Indiana, Nebraska, South Dakota, and Wisconsin. This geographic expansion highlights the virus’s ability to transmit efficiently across the swine population.
What Producers Should Know
Dr. Niederwerder emphasizes the importance of considering this emerging lineage when developing PRRS management strategies. Key considerations include:
- Herd Management: Evaluate herd closure and depopulation protocols.
- Vaccination: Update vaccination plans to address circulating strains.
- Surveillance: Enhance testing and monitoring to track the presence of PRRS strains in herds and understand regional risks for introduction and spread.
Accessing More Information
Further details on this emerging PRRS lineage are available in SHIC’s January eNewsletter, accessible at swinehealth.org.
Stay tuned to Swine Web for more updates on this critical swine health issue.
