In the mid-1990s, thousands of cattle in the United Kingdom (UK) were affected by an outbreak of a fatal neurological disease, bovine spongiform encephalopathy (BSE), commonly referred to as “mad cow disease.” Concern grew when it was discovered that some people who had eaten meat from infected cows had gotten a version of the disease called new variant Creutzfeldt-Jakob disease (nvCJD).
BSE, which is invariably fatal, is caused by a malformed protein that is not neutralized by high heat or other measures commonly used to kill bacteria, viruses, or other organisms. As a result of the UK outbreak, imports of British beef were banned from the United States and other countries.