Transmissible Spongiform Encephalopathies (TSEs) are a group of progressive neurodegenerative diseases caused by abnormal proteins called prions. These prions induce misfolding of normal proteins in the brain, leading to brain damage and the characteristic sponge-like appearance. TSEs affect both animals and humans, with notable examples including Bovine Spongiform Encephalopathy (mad cow disease) in cattle and Creutzfeldt-Jakob Disease in humans. TSEs are typically transmitted through contaminated tissues, such as during the consumption of infected meat or through medical procedures involving infected materials. Symptoms often include cognitive decline, motor dysfunction, and behavioral changes, with no known cure. The diseases are fatal, highlighting the importance of monitoring and controlling potential sources of prion infection.