The Swine Health Information Center (SHIC) is reporting increased activity for Porcine Reproductive and Respiratory Syndrome (PRRS) and Porcine Epidemic Diarrhea (PED) during November, while Influenza A activity declined to its lowest level in nearly a decade.
The findings were released as part of SHIC’s December domestic and global swine disease monitoring reports, which track diagnostic trends across the U.S. pork industry.
PRRS and PED Trending Higher
According to SHIC Associate Director Dr. Lisa Becton, PRRS case positivity rose to 48.5% in the wean-to-finish category, marking the highest level recorded since 2018.
PED case positivity also increased:
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Sow herds: up 6.5%
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Wean-to-finish pigs: 17.4%, above expected seasonal levels
Dr. Becton noted that increases in PRRS and PED are common during winter months but said current levels suggest heightened virus circulation in some regions.
Factors contributing to increased PRRS activity may include instability in sow farms, allowing virus leakage into wean-to-finish populations, along with both new infections and recirculation of endemic strains reported over the past 30 days.
For PED, seasonal factors such as fall manure pumping and environmental conditions may be contributing to higher detection rates.
Influenza A Activity Declines
In contrast, Influenza A case positivity in sow herds declined to its lowest level since 2015.
Dr. Becton said the exact cause is unclear but may reflect more proactive intervention strategies on sow farms, including vaccination programs and enhanced biosecurity practices that reduce viral transmission. Overall influenza activity may also simply be lower across the industry at this time.
Ongoing Monitoring Remains Critical
SHIC continues to emphasize the importance of surveillance, biosecurity, and timely diagnostics as disease pressures shift seasonally.
The full domestic and global swine disease monitoring reports are available at swinehealth.org.
