Final answer:
Humans contract variant Creutzfeldt-Jakob Disease by consuming infected animal products, particularly meat from cows with mad cow disease. Prions lead to fatal neurodegenerative diseases by misfolding proteins in the brain, which resists traditional sterilization methods and is usually transmitted through consumption of contaminated tissue rather than casual contact.
Step-by-step explanation:
Prions are abnormal, pathogenic agents that are responsible for causing variant Creutzfeldt-Jakob Disease (vCJD). Humans primarily contract this disease by consuming infected animal products, specifically meat from cows with bovine spongiform encephalopathy (BSE), also known as mad cow disease. Prions can misfold properly folded proteins in their host, leading to rapid degeneration of brain tissue and creating sponge-like holes in the brain.
Contrary to other infectious agents like viruses or bacteria, prions resist the usual means of sterilization due to their robustness against heat, chemicals, and radiation. Variant CJD is a fatal neurodegenerative disease, with symptoms including the loss of motor control, behavioral changes, and eventually death. Kuru, another prion disease, was spread among humans through ritualistic cannibalism, emphasizing the diverse transmission methods of prion diseases.
Transmission of prions from human to human has documented cases involving exposure to contaminated tissue during medical procedures, such as organ transplants or blood transfusions. However, there is no evidence for casual human-to-human transmission.