Although prion diseases are extremely rare in humans, emergency personnel should be familiar with these diseases as they are a potential public health risk. Until recently, it was thought that the smallest particle capable of transmitting disease was a virus. However, it has been demonstrated that, in certain cases, a protein alone is capable of transmitting disease. Protein particles, referred to as prions , have been identified as the causative agent of a group of diseases called transmittable spongiform encephalopathies .
Normal neurons produce a protein that is very similar in structure to the prion.
This protein is a part of the nerve cell membrane and is exposed to the body's extracellular fluid. However, when exposed to a prion, this membrane protein changes shape and the individual protein molecules interact to form large, insoluble complexes that are released into the extracellular fluid. These complexes are referred to as amyloid plaques. The presence of an amyloid plaque , or the absence of the normal membrane protein, interferes with neural function. It appears that prions are most frequently transmitted in food products.