Creutzfeldt-Jakob disease (CJD) is one of a group of rare diseases called 'transmissible spongiform encephalopathies (TSEs).' These diseases affect people and some kinds of animals. They attack the central nervous system and invade the brain, causing damage and eventual death.
Creutzfeldt-Jakob disease is very rare. Only about 1 case per million people occurs each year worldwide.
They are related, but not the same. Both are TSEs. But only people get Creutzfeldt-Jakob disease, and only cattle get mad cow disease (bovine spongiform encephalopathy, or BSE). Cattle are thought to get mad cow disease when they are fed contaminated beef by-products or bone meal.
It is possible for people to get a form of Creutzfeldt-Jakob disease (variant CJD, or vCJD) by eating beef from cattle with mad cow disease. The likelihood is very small, but not zero.Almost all of the people who have been infected this way ate beef while living in England during the 1980s and 1990s.
CJD is caused by a protein called a prion. (It is not caused by germs like bacteria and viruses.) Prions may cause other proteins in the brain to change shape, killing brain cells and making areas of the brain look spongy under a microscope. Most of the time, we don't know how or why this happens.
There is some evidence that vCJD may be transmitted by blood transfusion. The general public does not need to do anything special to protect against CJD. All other forms of CJD are NOT known to be spread from person to person through the air, through blood, or through sexual contact.
Health care workers and others who may be exposed to the blood or other body fluids of a CJD patient should take standard precautions.
Symptoms may occur months or even years after exposure. Early symptoms include loss of memory, clumsiness, slurred speech, and visual problems or hallucinations. As the illness gets worse, so do mental problems. A person may also have muscle twitches, weakness of the hands, feet, and limbs, and eventually coma.
Doctors sometimes test for sporadic CJD by testing electrical activity in the brain and examining spinal fluid. Familial CJD may be diagnosed with a blood test for the abnormal gene.
Diagnosis can be confirmed only through brain biopsy or autopsy (an examination of the brain after death). Autopsies are important in helping researchers track CJD.
One way CJD can be prevented is by stopping the spread of mad cow disease. Since 1990, the U.S. Department of Agriculture (USDA) has been testing American cattle and beef for BSE.
Import restrictions. In 1989, the USDA strictly limited the importation of cattle, sheep, and goats, and certain products from these animals, from countries where BSE was known to exist. These restrictions were later extended to include certain animals and products from all European countries.
A feed ban in place since 1997 forbids feeding U.S. livestock any cattle meat or bone meal that has been broken down by a process called 'rendering.' The Harvard Center for Risk Assessment concluded that this rule provides a major defense against BSE and CJD.
Last Updated: November 30, 2012