SHIC Offers Resources on PRRS 1-4-4 lineage 1c Outbreaks

Porcine reproductive and respiratory syndrome virus (PRRSV) 1-4-4 lineage 1c outbreaks in upper Midwest swine barns began in late 2020. To share information on this virulent strain impacting pork producers regionally, the Swine Health Information Center (SHIC), with co-sponsor American Association of Swine Veterinarians, offered a webinar on PRRSV 1-4-4 on February 4, 2021. SHIC also developed an episode of SHIC Talk, its podcast, posted on February 15, 2021, to share information on the PRRSv strain exhibiting dramatic clinical signs in all stages of production. In addition, completed SHIC projects focus on biosecurity that could help to prevent farm outbreaks.

Expert presenters on the webinar provided context from the practitioner, diagnostician, and monitoring perspectives to an audience of 323 people from 37 countries. While PRRSV 1-4-4 is not a new strain, experience with lineage 1c variant has shown it results in higher farrow to finish mortality, abortions, mummies, and slower growth in finishing pigs compared to other PRRSV strains. Drs. Paul Yeske, Swine Vet Center of St. Peter, Minnesota, and Daniel Linhares of Iowa State University, were presenters on the webinar and guests on the SHIC Talk Podcast.

Dr. Linhares shared information on his recently completed study addressing the industry’s need for the ability to better predict risk of a PRRS outbreak as well as to evaluate the level of biosecurity on their farms. The objective of this SHIC-funded study conducted at Iowa State University was to measure and benchmark the relationship between key biosecurity aspects and PRRS outbreaks in breeding herds, while validating a short biosecurity screening survey (44 questions). The analysis offers a flexible, shortened approach to screen breeding herd’s PRRS biosecurity vulnerability. Plus, this study highlights the value of using data to build upon the understanding of biosecurity risk in an operation.

Dr. Yeske also cautioned producers to be aware of efficacy and consistency with existing biosecurity practices, encouraging regular review to be sure what is supposed to be done is actually being done.

Like other transboundary or emerging diseases, PRRS could find its way onto the farm during marketing load out. SHIC has funded a study conducted by personnel from Iowa State University to try to objectively assess the issue of viral transfer during load out. The study evaluated if implementing a staged loading procedure for market pigs is effective at preventing transfer of swine pathogen contaminated particles from livestock trailers to the barn using fluorescent powder (Glo Germ) as a marking agent to be able to see traffic patterns. The study compared a conventional method of loading and a staged loading procedure. Four out of the five measuring points in the center alleyway of the barn had a level of contamination that measured significantly lower (p<0.05) for the staged loading protocol compared to the conventional loading protocol.

As the world deals with the COVID-19 pandemic, SHIC continues to focus efforts on prevention, preparedness, and response to novel and emerging swine disease for the benefit of US swine health. As a conduit of information and research, SHIC encourages sharing of its publications and research. Forward, reprint, and quote SHIC material freely. SHIC is funded by America’s pork producers to fulfill its mission to protect and enhance the health of the US swine herd. For more information, visit or contact Dr. Sundberg at [email protected].