What are prion diseases?
Prion diseases are very rare and are always fatal.
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 spread to humans by infected meat products. The most common form of prion disease that affects humans is Creutzfeldt-Jakob disease (CJD).
Types of prion diseases include:
- Creutzfeldt-Jakob Disease (CJD): A person can inherit this condition, 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. Acquired CJD is caused by exposure to infected tissue during a medical procedure, such as a cornea transplant.
- Gerstmann-Sträussler-Scheinker Disease (GSS): Extremely rare, but occurs at an earlier age, typically around age 40.
- Fatal Insomnia (FI): Rare hereditary disorder causing difficulty sleeping. There is also a sporadic form of the disease that is not inherited.
- 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. This type of the disease usually affects younger people.
- Kuru: This disease is 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 quickly lead to severe disability and death. In most cases, death occurs within a year.
What causes prion disease?
Prion diseases occur when normal prion protein, found on the surface of many cells, becomes abnormal and clump in the brain, causing brain damage. This abnormal accumulation of protein in the brain can cause memory impairment, personality changes, and difficulties with movement.
Who is at risk for prion diseases?
Risk factors for prion disease include:
- Family history of prion disease
- Eating meat infected by “mad cow disease”
- Infection from receiving contaminated corneas or from contaminated medical equipment
What are the symptoms of prion diseases?
Symptoms of prion diseases include:
- Rapidly developing dementia
- Difficulty walking and changes in gait
- Muscle stiffness
- Difficulty speaking
How are prion diseases diagnosed?
Prion diseases are confirmed by taking a sample of brain tissue during a biopsy or after death. Healthcare providers, however, can do a number of tests before to help diagnose prion diseases such as CJD, or to rule out other diseases with similar symptoms. Prion diseases should be considered in all people with rapidly progressive dementia.
The tests include:
- MRI (magnetic resonance imaging) scans of the brain
- Samples of fluid from the spinal cord (spinal tap, also called lumbar puncture)
- Electroencephalogram, which analyzes brain waves; this painless test requires placing electrodes on the scalp
- Blood tests
- Neurologic and visual exams to check for nerve damage and vision loss
How are prion diseases treated?
Prion diseases can’t be cured, but certain medicines 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.
Can prion diseases be prevented?
Properly cleaning and sterilizing medical equipment may prevent the spread of the disease. If you have or may have CJD, do 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.