<unk>  is an infectious disease believed to be due to a misfolded protein, known as a prion. Cattle are believed to have been infected from being fed meat and bone meal (MBM) that contained the remains of other cattle who spontaneously developed the disease or scrapie-infected sheep products. The outbreak increased throughout the United Kingdom due to the practice of feeding meat-and-bone meal to young calves of dairy cows.<unk>  prions are misfolded forms of the particular brain protein called prion protein. When this protein is misfolded, the normal alpha-helical structure is converted into a beta sheet. The prion induces normally-folded proteins to take on the misfolded phenotype in an exponential cascade. These sheets form small chains which aggregate and cause cell death. Massive cell death forms lesions in the brain which lead to degeneration of physical and mental abilities and ultimately death. The prion is not destroyed even if the beef or material containing it is cooked or heat-treated under normal conditions and pressures. Transmission can occur when healthy animals come in contact with tainted tissues from others with the disease, generally when their food source contains tainted meat. The British Government enquiry took the view that the cause was not scrapie, as had originally been postulated, but was some event in the 1970s that could not be identified. Spread to humans Spread to humans is believed to result in variant Creutzfeldt–Jakob disease (vCJD). The agent can be transmitted to humans by eating food contaminated with it. Though any tissue may be involved, the highest risk to humans is believed to be from eating food contaminated with the brain, spinal cord, or digestive tract.
Bovine spongiform encephalopathy
Variant Creutzfeldt–Jakob disease
Creutzfeldt–Jakob disease
Powassan encephalitis
Saint Louis encephalitis
Eastern equine encephalitis
Japanese encephalitis
Viliuisk encephalomyelitis