In its latest domestic surveillance update, the Swine Health Information Center (SHIC) reports increased porcine reproductive and respiratory syndrome (PRRS) activity, regional spikes in porcine epidemic diarrhea (PED), and declining cases of Mycoplasma hyopneumoniae.
As part of its May 8 newsletter, SHIC released its monthly domestic and global swine disease monitoring reports. “This month’s domestic report highlights a spike in PRRS virus case positivity, regional increases in PED detections, and reduced incidence of Mycoplasma hyopneumoniae,” says Dr. Lisa Becton, SHIC Associate Director.
Becton notes that April 2025 saw the highest PRRS case positivity for any April since 2018, especially in the wean-to-finish age group. “It was a significant amount of viral activity,” she says. Variant L1C.5.32 had the highest level of detection for any PRRS variant in 2025, and when combined with other ORF5 variants recovered from veterinary diagnostic labs, represented 42 percent of all ORF5s found that month.
PED cases also rose regionally, particularly in sow herds across Minnesota. April also brought seasonal increases in case positivity for influenza A virus. However, Becton says there is some good news on the respiratory disease front. “For Mycoplasma hyopneumoniae monitoring, the first quarter of 2025 showed the lowest historical positive cases confirmed through tissue diagnosis,” she said.
This month’s domestic report also includes a bonus page introducing the new PRRS virus nomenclature system and its implementation in SHIC’s disease monitoring dashboards and BLAST tool.
“The bonus page provides insight into PRRS evolution and the distribution of specific strains over time, space, and age groups,” Becton explains. “This enhances the ability to track outbreaks, identify emerging variants, and understand genetic relationships between viral sequences.”Tools such as lineage distribution by month and detailed lineage breakdowns allow veterinarians and producers to make more informed decisions. “The goal of this information is to help producers and their vets understand the viral changes and implement different management strategies to reduce the impact of the PRRS virus,” said Becton.
On the global front, SHIC reports a surge in foot and mouth disease (FMD) cases across Europe and Asia. “We’ve seen increased incursions in Hungary and Slovakia,” said Becton. “South Korea has had 16 FMD outbreaks since mid-March, which shows continued movement of the virus.” A new serotype, SAT1, has been identified in the Near East and is spreading across several countries.
Meanwhile, African Swine Fever (ASF) continues to rise in Moldova and Romania, with 2025 cases already outpacing 2024 levels. The United Kingdom maintains heightened border surveillance in response to ASF and FMD risks, resulting in increased seizures of illegal meat products.
Becton stresses the implications of these global disease developments for North America. “It’s important for producers to be aware of both ASF and FMD, because these help highlight potential risk points—like illegal meats or contaminated clothing and footwear,” she said. “As people travel overseas, they may come into contact with areas where these infections are active, so heightened bio-security at home is essential.”
She says many bio-security practices already in place to manage domestic diseases can also protect against foreign animal disease incursions. “It’s vital to maintain vigilance and awareness so we can prevent these diseases from entering the U.S. and affecting our sow herds.”
The Swine Disease Reporting System (SDRS) and Global Swine Disease Reporting System updates are available through SHIC’s May newsletter. Becton also encourages pork producers and veterinarians to access additional resources at swinehealth.org. “There’s a recent foot and mouth disease webinar we co-sponsored with the American Association of Swine Veterinarians, and the recording is available on our site,” she added.
With both domestic and global pressures mounting, SHIC continues to provide tools, surveillance, and guidance to help the swine sector respond with knowledge and resilience. •
— By Harry Siemens
