Nothing to be mad about … 20 years after BSE in Washington
By Dr. Amber Itle, Washington State Veterinarian
Washington State Department of Agriculture
Bovine spongiform encephalopathy (BSE) is a progressive neurological disease of cattle caused by prions, which are infectious agents made up of protein material. The prion proteins affect the brain structure of infected animals, resulting in neurologic signs including behavioral changes, coordination problems, weight loss, and death. There are two types of BSE — classical and atypical. Neither form is contagious.
Christmas Eve 2003, Washington state had the country’s first detection of classical bovine spongiform encephalitis (BSE) in a cow imported from Canada. That was also the last detection of classical BSE in the United States likely due to USDA APHIS implementing a three-tiered strategy to mitigate the disease including 1) removal of specified risk materials – or the parts of an animal that would contain BSE should an animal have the disease – from all animals presented for slaughter; 2) imposing universal changes in cattle feeding practices that ban potentially BSE infectious tissues known as “specified risk materials” (SRM) from all animal feeds, pet foods, and fertilizers; and 3) implementation of the ongoing BSE surveillance program that allows USDA to detect the disease if it exists at very low levels in the U.S. cattle population.
Since 2003, there have been six sporadic and rare detections of atypical BSE detected in the United States due to a spontaneous change in the prion proteins in older adult cattle. The most recent case was detected in May 2023 in a 5-year-old mixed breed beef cow that was down on arrival at a slaughter facility in South Carolina. Unfortunately, the carcass had been processed prior to results resulting in 13,000 pounds of beef that had to be disposed of. The EID tag in the infected animal was key in being able to trace out to three direct progeny (a heifer and two steers). The trace also was able to determine that the cow was purchased at a bred heifer sale between 2015-16 at a Tennessee livestock market and came on a truck with 20 animals that could be traced to five locations. This is a true testament to the importance of animal disease traceability and the use of electronic individual identification for rapid response.
At about the same time, the World Organization for Animal Health (WOAH) adopted changes to the BSE chapter, removing atypical BSE from reporting, and investigation sampling/surveillance plan requirements. That means that atypical BSE will not impact trade negotiations, will make surveillance requirements less burdensome, and will allow more opportunities to focus on those extremely rare classical cases. Because feed bans have been in place long enough to bypass the lifespan of animals that may have been exposed to the practice, surveillance efforts are being updated to reflect risk. As a result, USDA APHIS updated its BSE response plan in June 2023.
For more information and historical information on BSE, please visit the USDA APHIS website.
