Creutzfeldt-Jakob disease (CJD) is a rapidly progressive human prion disease. Once someone contracts the neurodegenerative disorder, death usually occurs within one year of illness onset. The disease almost always has a fatal outcome for those who get the infection.
According to the CDC, the disease appears with seemingly no pattern in 85% of patients, making it difficult to know the cause. Others with the disease may contract it because of inherited mutations of the prion protein gene.
Variant Creutzfeldt-Jakob disease (vCJD) outbreaks have been scientifically associated with the same agent that causes bovine spongiform encephalopathy (BSE), also known as mad cow disease. Consumption of BSE-contaminated food could lead to vCJD.
Note that classic CJD is not the same as vCJD, so classic CJD is not related to BSE. CJD and vCJD have different genetic profiles of the prion protein