Recent reports of the emergence and spread of foot-and-mouth disease virus (FMDV) SAT1 serotype are highlighting a concerning shift in the global landscape of this virus. The Swine Health Information Center-funded Global Swine Disease Monitoring Reports, led by Dr. Sol Perez at the University of Minnesota, have highlighted the newly affected countries in monthly publications.
“For FMDV, immunity is serotype-specific, meaning infection or vaccination against a given serotype does not confer protection against a different serotype,” Perez says in a SHIC article.
A Rapid Geographic Shift
Historically, SAT1 was maintained within endemic locations in East and Southern Africa. However, in 2025, SAT1 demonstrated a “concerning expansion” beyond its traditional geographic range, with confirmed detections of two cocirculating subtypes across Western Asia and North Africa. The increasing circulation of SAT1 poses a growing risk to previously unaffected regions, including southeast Europe and potentially beyond. As this serotype expands its geographic range, it creates additional pathways for introduction into new regions and countries, increasing the overall likelihood of transboundary spread, Perez notes.
The Immunity Gap
The primary concern for animal health officials is that FMDV immunity is serotype-specific. Current vaccination programs in many affected regions target serotypes O, A and Asia-1. Because these vaccines provide no cross-protection against SAT1, livestock populations remain effectively susceptible, research shows. This “ecological space” has allowed SAT1 to spread rapidly through populations that were previously considered protected.
Drivers of FMD Transmission
SAT1’s expansion is likely due to several factors, Perez says.
- Livestock Movement: Informal cross-border movement of small ruminants, which may carry subclinical infections, is a primary driver.
- Environmental Pressures: Drought and land-use changes have increased contact between wildlife reservoirs and domestic herds.
- Vaccine Limitations: A lack of SAT1-specific vaccine stockpiles and gaps in surveillance have hindered rapid response efforts.
FMD Implications for the United States
Although the U.S. remains free of FMD, the expansion of SAT1 into new regions of the world increases the complexity of global risk, Perez says. The emergence of two cocirculating subtypes (topotypes SAT1/I and SAT1/III) creates more pathways for the virus to enter the U.S. via international travel, contaminated animal products, or fomites.
“These global developments underscore the need to strengthen early detection and surveillance systems, maintain stringent biosecurity measures across livestock value chains, and ensure that vaccine preparedness strategies are sufficiently flexible to incorporate emerging serotypes such as SAT1,” Perez says.
For the U.S. pork industry, this serves as a critical reminder to maintain stringent biosecurity measures and support global monitoring efforts to prevent a domestic outbreak.
