Thanks to decisive, science-based preventative measures, bovine spongiform encephalopathy (BSE) has become exceedingly rare in the United States. Continued vigilance and compliance with feed regulations remain important though, according to a new FDA video that outlines the history of BSE and the results of rules designed to prevent its spread.

BSE emerged in the late 1980s and early 1990s, primarily in the United Kingdom. Scientists soon linked the deadly wasting disease to cattle’s consumption of feeds containing animal byproducts that carried the misfolded proteins, known as prions, which cause the condition.

Scientists also linked the human form of the disease, variant Creutzfeldt-Jakob disease (vCJD) to consumption of beef contaminated with the BSE prions. Cases of vCJD peaked in the year 2000, when 28 people contracted the fatal disease. In the United States, only four cases of vCJD have been confirmed, and all of those people likely contracted the disease while living or traveling overseas.

In the early 1990s, the USDA issued import restrictions on beef from the United Kingdom and other countries with BSA and initiated a domestic surveillance program. Also, the FDA and USDA worked with beef processors to remove specific risk materials (SRMs), primarily nervous-system tissue, from beef carcasses. In 1997, based on scientific evidence, the FDA issued its original BSE-related feed restrictions, removing mammalian proteins from cattle feeds. In 2008, the agency issued its enhanced feed regulations banning high-risk cattle tissues from all animal feeds.

Between 2004 and 2008, the U.S. surveillance program resulted in testing of 750,000 cattle. In 2008 the surveillance program was scaled back to test around 40,000 cattle per year.

The first case of BSE found in the United States was in 2003, in a cow that had been imported from Canada. Since then, there was one confirmed case in Texas in 2005, one in Alabama in 2006 and one in California in 2012. Each of those domestic cases was determined to be a rare, atypical form of BSE that occurs naturally. In May, 2015, the World Organization for Animal Health (OIE) recognized atypical BSE as naturally occurring and determined that cases should not affect a country’s risk status.

The OIE currently rates the United States as having “negligible risk” for BSE.

Globally, according to the video, BSE peaked in 1992 when over 35,000 cases were identified. By 2012, the global incidence was reduced to 13 cases.

The FDA video credits efforts to remove BSE risk materials from feeds for the dramatic reduction in cases. The agency stresses though, that the industry remain vigilant and compliant with regulations and feed-manufacturing practices intended to prevent BSE.

View the video from FDA.