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Creutzfeldt-Jakob Disease (CJD)
(Subacute Spongiform Encephalopathy; Creutzfeldt-Jakob's Disease)
Creutzfeldt-Jakob disease (CJD) is the most common human prion disease. It occurs worldwide and has several forms. CJD symptoms include dementia, myoclonus, and other CNS deficits; death usually occurs between 4 mo and 2 yr after infection, depending on the CJD form. Treatment is supportive.
CJD has several forms:
sCJD is the most common type, accounting for about 85% of cases. sCJD typically affects people > 40 yr (median, about 60 yr).
Familial CJD occurs in about 5 to 15% of cases. Inheritance is autosomal dominant, age at onset is usually earlier than that in sCJD, and disease duration is longer.
Acquired CJD probably accounts for < 1% of cases. It has occurred after the ingestion of beef contaminated by prions (in vCJD). Iatrogenically, CJD has been acquired via use of cadaveric corneal or dural transplants, stereotactic intracerebral electrodes, or growth hormone prepared from human pituitary glands.
vCJD is rare. Most cases have occurred in the United Kingdom (UK), which had 177 cases as of May 2015, compared with 52 cases in all other European and non-European countries. vCJD occurs after ingestion of beef from cattle with bovine spongiform encephalopathy (BSE), also called mad cow disease.
In vCJD, symptoms develop at a younger average age (< 30 yr) than in sCJD. In recent cases, the incubation period (time between ingestion of contaminated beef and development of symptoms) has been 12 to > 20 yr.
In the early 1980s, because of relaxed regulations for processing animal by-products, contaminated tissue, probably from sheep infected with scrapie or cattle infected with BSE, introduced the scrapie prion protein (PrP Sc ) into cattle feed. Hundreds of thousands of cattle developed BSE. Despite widespread exposure, relatively few people who ate meat from affected cattle developed vCJD.
Because the incubation period in BSE is long, a connection between BSE and contaminated feed was not recognized in the UK until BSE had become an epidemic. The BSE epidemic came under control after a massive slaughter of cattle and after changes in the rendering procedures, which drastically reduced contamination of meat by nervous system tissue. In the UK, the annual number of new cases of vCJD, which peaked in 2000, has steadily declined, with only 1 case in 2013.
Four cases of vCJD have been linked to blood transfusion; they occurred in people who received transfusions between 1996 and 1999. In the UK, about 1/2000 people may carry vCJD (based on examination of a large number of appendix tissue samples) but have no symptoms; these people may transmit the disease if they donate blood or have a surgical procedure. Whether there is a latent pool of people who have received contaminated blood transfusions and who are thus at risk of later development of vCJD is unclear. However, new blood donor referral criteria related to vCJD may further reduce the risk of vCJD transmission by blood transfusion, which is already very low outside of France and the UK.
Although no case of vCJD originating in North America has been reported, BSE has been reported in a few North American cattle (4 in the US and 19 in Canada).
About 70% of patients with CJD present with memory loss and confusion, which eventually develop in all patients; 15 to 20% present with incoordination and ataxia, which often develop early in the disease. Myoclonus provoked by noise or other sensory stimuli (startle myoclonus) often develops in the middle to late stages of disease. People with vCJD present with psychiatric symptoms (eg, anxiety, depression), rather than memory loss. Later symptoms are similar in both forms.
Although dementia, ataxia, and myoclonus are most characteristic, other neurologic abnormalities (eg, hallucinations, seizures, neuropathy, various movement disorders) can occur.
Ocular disturbances (eg, visual field defects, diplopia, dimness or blurring of vision, visual agnosia) are common in sCJD.
CJD should be considered in elderly patients with rapidly progressive dementia, especially if accompanied by myoclonus or ataxia. However, other disorders can mimic CJD and must be considered; they include
Rapidly progressive Alzheimer disease
Hashimoto encephalopathy (an autoimmune encephalopathy that is characterized by high thyroid antibody levels and that responds to corticosteroids)
Intravascular lymphoma (a rare lymphoma)
Encephalitis that affects the limbic system, brain stem, and cerebellum
Lewy body dementia
Intoxication with lithium or bismuth.
CJD is suspected in symptomatic younger patients when they have been exposed to prion-contaminated beef in the UK or other at-risk countries or who have a family history of CJD (familial CJD). Rarely, sCJD develops in young patients, but in such patients, other diseases must be excluded.
Diagnosis may be difficult.
The best noninvasive diagnostic test for CJD is
It can detect evolving patchy areas of hyperintensity (bright areas) in the cortical ribbon, which strongly suggest CJD.
Proteins 14-3-3, brain-specific enolase, and tau are commonly increased in CSF but are not specific for CJD. A relatively new CSF test, called real-time quaking-induced conversion (RT-QUIC), amplifies and detects minimal amounts of prion activity (conformational change of PrP C into PrP Sc ) in CSF; this test appears to be more accurate than previous CSF tests. A similar test can reliably detect evidence of vCJD by identifying prions in urine.
EEG is done. Results are positive in about 70% of patients with CJD; EEG shows characteristic periodic sharp waves, but this pattern typically occurs late in the disease and may be transient. Brain biopsy is usually unnecessary.
Because there is no effective treatment, prevention of transmissible CJD is essential.
Workers handling fluids and tissues from patients suspected of having CJD must wear gloves and avoid mucous membrane exposure. Contaminated skin can be disinfected by applying 4% Na hydroxide for 5 to 10 min, followed by extensive washing with water.
Steam autoclaving of materials at 132° C for 1 h or immersion in Na hydroxide 1 N (normal) or 10% Na hypochlorite solution for 1 h is recommended. Standard methods of sterilization (eg, exposure to formalin) are ineffective.
The US Department of Agriculture (USDA) currently carries out BSE surveillance for 2000 to 5000 cattle/mo. In 2004, a positive BSE case in the US caused testing to be expanded to an average of 1000 cattle/day, but testing was later reduced to 40,000/yr (0.1% of the cattle that are slaughtered).
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