Prion diseases are a group of rare, progressive neurodegenerative disorders caused by misfolded proteins known as prions. These abnormal proteins induce other normal proteins in the brain to also misfold, leading to brain damage and severe neurological symptoms. Common examples include Creutzfeldt-Jakob disease and mad cow disease. These diseases are unique because they are not caused by bacteria or viruses, making them resistant to standard treatments. Prion diseases can be transmitted through contaminated food, medical procedures, or inherited genetic mutations. Symptoms often include memory loss, personality changes, and difficulties with movement, ultimately leading to severe disability and death.