As PRRSV strains continue to affect pork production in the US and around the world, SHIC and AASV held a webinar on February 21, 2023, to provide the latest information on challenges caused by emerging strains of this virus. Webinar presenters addressed the PRRSV L1C variant of RFLP 1-4-4 and PRRSV L1C 1-2-4 affecting the US swine population, and Rosalia, a PRRSV-1 strain with increased virulence affecting swine production in Spain. SHIC’s mission includes sharing global disease risk and perspectives like these surrounding PRRSV in the effort to safeguard US swine herd health.
The webinar featured presenters Dr. Enric Mateu, Autonomous University of Barcelona (Spain), Drs. Daniel Linhares and Giovani Trevisan, Iowa State University, Dr. Paul Yeske, Swine Vet Center (St. Peter, Minnesota), and Dr. Clayton Johnson, Carthage (Illinois) Veterinary Service. Over 300 individuals registered for the webinar with 167 participants watching live from 18 countries and 20 US states. Attendees learned about Rosalia’s significant impact on swine production in Spain, how veterinary diagnostic laboratory data reveals PRRSV movement and predicts spread, as well as on-farm experience with prevention and controls measures for PRRSV L1C variant in the US.
Dr. Mateu said 18 million pigs in Spain were impacted by Rosalia. For perspective, there are 34 million pigs total in Spain and 146 million in the EU. The primary area impacted spans 31,000 square miles in the northeast quadrant of the country. In the area of greatest prevalence, 1,000 sow farms, averaging 1,400 sows each, are present. Further, 490 farms with nursery operations exist in that area of viral circulation and 8,000 farms where pigs are finished. On sow farms, the PRRS vaccination rate is 70%, less than 20% of nursery farms are vaccinated, and less than 5% of finishing farms.
Spanish pork producers affected by Rosalia experienced abortion storms in sow herds, sow mortality, stillbirths, high mortality in suckling piglets and weaners, fewer health issues in finishing pigs, but decreased feed conversion rates. Dr. Mateu said these realities resulted in a high economic impact. On average, the most affected farms lost 15% to 20% of their annual income.
The presentation included statistics on Rosalia consequences as it has affected production in waves. Dr. Mateu said Spain is probably in a phase with decreasing impacts though the industry remains vigilant in its efforts to combat Rosalia’s impact. Vaccination, McRebelTM (management changes to reduce exposure to bacteria to eliminate losses from PRRS), changing farrowing schedules, and depopulation have all been implemented with varying results.
Drs. Daniel Linhares and Giovani Trevisan shared information about PRRSV monitoring on the Swine Disease Reporting System, a SHIC-funded collaborative project among 5 veterinary diagnostic laboratories. SDRS shares information on the activity of endemic and emerging pathogens affecting the US swine population, assisting veterinarians and producers in making informed decisions on disease prevention, detection, and management.
Using data collected from the five veterinary diagnostic labs participating in SDRS, Drs. Linhares and Trevisan shared information on PRRSV evolution and genetic variability across states. Data included information on PRRSV L1C RFLP 1-2-4. From 2009 to 2021, per SDRS, there were 421 detections of this strain then in 2022, there were 264 classifications. Their data shows PRRSV L1C variant is still an eminent animal health and production threat and is moving east, threatening 1.5 million or more sows in 2023. They reminded webinar participants of the importance of biocontainment and biosecurity in eastern states to prevent introduction of that strain into pig populations at risk in that region.
SDRS monthly reports can be accessed on the SHIC website.
Minnesota-based practitioner, Dr. Paul Yeske, shared information on what to consider during a PRRS outbreak and herd closure, also addressing depopulation/repopulation strategies. When moving through the early days of a PRRS break, Dr. Yeske said abortions and farrowing sows with retained pigs are the most common cause of sow mortality. Assisting sows in this process, just as assisting with farrowing, is essential.
His advice also included increasing breeding targets as much as possible, breeding back sows that aborted, and identifying open sows as soon as possible. To save pigs, Dr. Yeske recommended moving piglets as needed and treating them more aggressively.
Regarding herd stabilization, Dr. Yeske walked through three scenarios: allow herd to remain positive, eliminate the field strain, and depopulation/repopulation. He shared processes, recommendations, and results as well as timelines. The overview addressed McRebel-like procedures and Dr. Yeske’s cautions regarding its implementation, diagnostic monitoring, and an early weaning strategy. Depopulation/repopulation as a tool to address PRRS breaks serves as a viable strategy in the US production model, per Dr. Yeske, due to multi-site production.
When talking about biosecurity, Dr. Yeske emphasized the need for bio-containment, or how to keep the virus on the site, as equally essential to bio-exclusion, keeping the virus out. He said bio-containment is the forgotten part of biosecurity, a process addressing showering out of barns and handling mortalities as well as disposal of boots and coveralls among other practices.
Dr. Clayton Johnson shared experience with PRRSV breaks on three sow farms, each varying in intensity along with remarks on what’s working to combat PRRS. Biosecurity, understanding PRRSV strain lineage, and PRRS vaccination all have been effective tools for PRRS management. However, herd closure, prevention of latent PRRS clinical resurgence, regional PRRS management programs, and grow/finish biosecurity are all opportunities that need attention. Dr. Johnson said questions surrounding the origin of PRRSV strains lead to confusion as does knowing where the emerging strain will display virulence, and how isolate specific PRRS management strategies should be.
A discussion on tools needed for PRRSV break management was part of Dr. Johnson’s presentation as well as identification of research needs. He suggested the industry may need a working group with a focus on the latest novel PRRS strain. Another research need is barn-level examination on piglet vaccination, piglet antibiotic administration at weaning, pre-farrow vaccination of sows, and the impact of McRebel.
Complete presentations, as well as attendee questions for speakers, are all included in the full webinar, available on the AASV website.
SHIC/AASV sponsored webinars bring together subject matter experts to discuss current issues facing US pork producers and practitioners. Previous webinars are posted online for convenient access at https://aasv.org/members/only/video/webinars/.
Do you have a recommendation for a topic to be addressed in this format? SHIC and AASV would like your input! Reach out to SHIC Executive Director Dr. Paul Sundberg at psundberg@swinehealth.org or AASV Director of Public Health and Communications Dr. Abbey Canon at canon@aasv.org with your webinar recommendations.
SHIC, launched by the National Pork Board in 2015 solely with Pork Checkoff funding, 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 http://www.swinehealth.org or contact Dr. Paul Sundberg at psundberg@swinehealth.org.