Several conditions fall under the term prion diseases. A prion is a type of protein that can trigger normal proteins in the brain to fold abnormally. Prion diseases can affect both humans and animals and are sometimes transmitted to humans by infected meat products. The most common form of prion disease that affects humans is Creutzfeldt-Jakob disease (CJD).
Prion diseases lead to brain damage when prion proteins cause abnormal clumping in the brain. This abnormal accumulation of protein in the brain can cause memory impairment, personality changes, and difficulties with movement. Experts still don't know a lot about prion diseases, but unfortunately, these disorders are generally fatal.
Prion diseases are rare. About 300 cases are reported each year in the U.S.
Types of prion diseases include:
CJD. This condition can be inherited, in which case it's called familial CJD. Sporadic CJD, on the other hand, develops suddenly without any known risk factors. Most cases of CJD are sporadic and tend to strike people around age 60. Symptoms of CJD quickly lead to severe disability and death. In most cases, death occurs within a year.
Variant CJD. This is an infectious type of the disease that is related to “mad cow disease.” Eating diseased meat may cause the disease in humans. The meat may cause normal human prion protein to develop abnormally. The disease is also thought to have been spread to people receiving cornea transplants from infected donors and from contaminated medical equipment. This type of the disease usually affects younger people.
Kuru. This disease has largely been seen in New Guinea. It's caused by eating human brain tissue contaminated with infectious prions. Because of increased awareness about the disease and how it is transmitted, kuru is now rare.
Symptoms of prion diseases include:
Rapidly developing dementia
Difficulty walking and changes in gait
Prion diseases can only be confirmed by taking a sample of brain tissue during a biopsy or after death. Doctors, however, can do a number of tests to help diagnose prion diseases such as CJD, or to rule out other diseases with similar symptoms.
These tests include:
MRI scans of the brain
Samples of fluid from the spinal cord (spinal tap)
Electroencephalogram, which analyzes brain waves; this painless test requires placing electrodes on the scalp
Neurologic and visual examinations to evaluate for nerve damage and vision loss
Prion diseases can't be cured, but certain medications may help slow their progress. Medical management focuses on keeping people with these diseases as safe and comfortable as possible despite progressive and debilitating symptoms.
Properly sterilizing medical equipment may prevent the spread of the disease. If you have or may have CJD, you should not donate organs or tissue, including corneal tissue. Newer regulations that govern the handling and feeding of cows may help prevent the spread of prion diseases.
As prion diseases progress, people with these diseases generally need help taking care of themselves and their daily needs. In some cases they may be able to stay in their homes, but they eventually may need to move to a care facility.