Proteins are long chains of amino acids that have to fold together into a unique shape or conformation to gain function in the cells. The normal, harmless prion is usually designated PrP C (C stands for cellular) and the abnormal, infectious form (which causes the disease) is PrP Sc (Sc stands for prototypical prion disease–scrapie). It also tends to cause more rapid deterioration of a person’s abilities than Alzheimer’s disease or most other types of dementia.Ĭurrent scientific consensus maintains that abnormal forms of normal cellular proteins called prions cause CJD in people and TSE in animals. However, CJD causes unique changes in brain tissue which can be seen at autopsy. Some symptoms of CJD can be similar to symptoms of other progressive neurological disorders, such as Alzheimer’s and Huntington’s disease. Variant CJD begins primarily with psychiatric symptoms, affects younger individuals than other types of CJD, and has a longer than usual duration from onset of symptoms to death. Pneumonia and other infections often occur in these individuals and can lead to death. They eventually lose the ability to move and speak, and enter a coma. They often develop involuntary muscle jerks called myoclonus, and they may go blind. As the illness progresses, peoples’ mental impairment becomes severe. People with the disease, especially with FFI, also may experience insomnia, depression, or unusual sensations. Initially, individuals experience problems with muscle coordination, personality changes (including impaired memory, judgment, and thinking), and impaired vision. Top What are the symptoms of the disease?Īlthough sporadic TSE includes five distinct subtypes of sporadic CJD and sporadic fatal insomnia (sFI), overall they are characterized by rapidly progressive dementia.
To date no transmission of CWD to humans has been reported. Chronic wasting disease (CWD) affects elk and deer and is increasingly prevalent in certain areas in the United States. These include BSE, mink encephalopathy, feline encephalopathy, and scrapie, which affects sheep and goats. Other TSEs are found in specific kinds of animals. To date, about 260 cases of vCJD, mostly in the United Kingdom, have been reported related to consuming beef but none in which the disease was acquired in the U.S. FFI and GSS are extremely rare hereditary diseases, found in just a few families around the world. Kuru is considered an acquired prion disease. Kuru was identified in people of an isolated tribe who practiced ritual cannibalisms in Papua, New Guinea and has now almost disappeared. Other human TSEs include kuru, fatal familial insomnia (FFI), and Gerstmann-Straussler-Scheinker disease (GSS). CJD is the most common of the known human TSEs. Spongiform refers to the characteristic appearance of infected brains, which become filled with holes until they resemble sponges when examined under a microscope. A prion-derived from “protein” and “infectious”-causes CJD in people and TSEs in animals. A type of CJD called variant CJD (or vCJD) can be acquired by eating meat from cattle affected by a disease similar to CJD called bovine spongiform encephalopathy (BSE) or, commonly, “mad cow” disease.ĬJD belongs to a family of human and animal diseases known as the transmissible spongiform encephalopathies (TSEs) or prion diseases. Since CJD was first described in 1920, fewer than one percent of cases have been acquired CJD. There is no evidence that CJD is contagious through casual contact with someone who has CJD. In acquired CJD, the disease is transmitted by exposure to brain or nervous system tissue, usually through certain medical procedures.About 10 to 15 percent of cases of CJD in the United States are hereditary. In hereditary CJD, the person may have a family history of the disease and test positive for a genetic mutation associated with CJD.This is by far the most common type of CJD and accounts for at least 85 percent of cases. In sporadic CJD, the disease appears even though the person has no known risk factors for the disease.As the illness progresses, mental deterioration becomes pronounced and involuntary movements, blindness, weakness of extremities, and coma may occur. In the early stages of the disease, people may have failing memory, behavioral changes, lack of coordination, and visual disturbances. Typical onset of symptoms occurs at about age 60, and about 70 percent of individuals die within one year. CJD usually appears in later life and runs a rapid course. It affects about one person in every one million per year worldwide in the United States there are about 350 cases per year. How can people avoid spreading the disease?Ĭreutzfeldt-Jakob disease (CJD) is a rare, degenerative, fatal brain disorder.
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