Transmissible Spongiform Encephalopathies, an IFT Scientific Status Summary

Transmissible spongiform encephalopathies (TSEs) encompass a group of diseases affecting several mammalian species—mink, cats, sheep, goats, cattle, deer, and elk (Figure 1)—including humans. These diseases are transmissible because they are capable of being transferred from one animal to another, spongiform because they cause the appearance of sponge-like holes in the brain of those affected, and encephalopathic because they are neurodegenerative diseases of the brain. TSEs continue to pose a concern with respect to animal and human health. This was recently underscored by discovery of bovine spongiform encephalopathy (BSE)–positive cattle in Canada and the United States and the apparent spread of variant CreutzfeldtJakob Disease (vCJD) in humans through blood transfusions. The TSE threat to humans can be attributed to the fact that there are direct and indirect routes of exposure. As a result, the U.S. government, including the U.S. Dept. of Agriculture, the Food and Drug Administration, and the Environmental Protection Agency, is being called on to develop the regulatory framework necessary to protect the public, the animals, and the environment. From an economic perspective, TSEs have brought about trade disruption and additional processing requirements resulting in hardship for cattle producers, meat processors, feed manufacturers, and renderers. The impacts include changes in slaughtering and deboning techniques, implementation of special handling procedures for specified risk materials (SRMs), additional labeling requirements, and significant disposal and waste-handling challenges for the industry. From a government perspective, TSEs have created a need for increased regulation and monitoring of meat processing and rendering facilities, with resultant effects on the food and feed industries (for example, ingredients derived from edible rendering, including fats, oils, and emulsifiers). Summarizing the scientific, regulatory, and trade landscape of TSEs has proven to be quite a challenge because of the constantly evolving information pertaining to these diseases. This Scientific Status Summary attempts to capture major findings and trends, and we encourage the reader to check for updates, as new research may alter our current understanding.