Mad cow disease is an illness that attacks the brain and spinal cord in adult cattle. Humans who become infected, usually by eating tissue from diseased cattle, will die of a similar brain disease that may develop over many years. The scientific name for mad cow disease in cattle is called bovine spongiform encephalopathy (meaning sick brain) or BSE, meaning a sickness of the cow's brain. Mental and physical abilities deteriorate and myriad tiny holes appear in the cortex causing it to appear like a sponge (hence 'spongiform') when brain tissue obtained at autopsy is examined under a microscope. If humans eat diseased tissue from cattle, they may develop the human form of mad cow disease known as variant Creutzfeldt-Jakob disease (vCJD) or new variant Creutzfeldt-Jakob disease (nvCJD)