Which microscopic organism is responsible for causing Creutzfeldt-Jakob disease?

Creutzfeldt-Jakob disease (CJD) is caused by prions, which are misfolded proteins that lead to neurodegenerative diseases. Unlike other pathogens, prions do not have nucleic acids (DNA or RNA) and are responsible for a number of progressive and often fatal conditions in both humans and animals. The mechanism by which prions cause disease involves the conversion of normal cellular proteins into abnormal prion forms, leading to brain damage and the characteristic symptoms associated with CJD.

Because prions lack the biological structure typical of bacteria, viruses, or fungi, they represent a distinct category of infectious agent. Bacteria are single-celled organisms that can reproduce independently, viruses require host cells for replication, and fungi are a diverse group of organisms including yeasts and molds. Each of these has different structures and replication methods that do not apply to prions. Understanding the unique nature of prions helps clarify their role in diseases like Creutzfeldt-Jakob disease.