About vCJD
Variant CJD was first described in 1996 in the United Kingdom. It has different
clinical and pathologic characteristics from classic CJD. Each disease also has a
particular genetic profile of the prion protein gene. (See table
below). The median age at death for vCJD patients is 28 years, compared with 68
years for patients with classic CJD. The median duration of illness for vCJD is 14
months, compared to 5 months for classic CJD.
Clinical and Pathologic
Characteristics
Distinguishing Classic CJD from variant CJD
| Characteristic |
Classic CJD |
Variant CJD |
| Median age at death |
68 years |
28 years |
| Median duration of illness |
4-5 months |
13-14 months |
| Clinical signs and symptoms |
Dementia; early neurologic signs |
Prominent psychiatric/behavioral symptoms; painful
dyesthesiasis; delayed neurologic signs |
| Periodic sharp waves on
electroencephalogram |
Often present |
Often absent |
| "Pulvinar sign" on MRI* |
Not reported |
Present in >75% of cases |
| Presence of "florid plaques" on
neuropathology |
Rare or absent |
Present in large numbers |
| Immunohitochemical analysis of brain
tissue |
Variable accumulation |
Marked accumulation of protease-resistance prion
protein |
| Presence of agent in lymphoid tissue |
Not readily detected |
Readily detected |
| Increased glycoform ratio on immunoblot
analysis of protease-resistance prion protein |
Not reported |
Marked accumulation of protease-resistance prion
protein |
| Source: Adapted from
Belay E., Schonberger L. Variant Creutzfeldt-Jakob Disease and Bovine
Spongiform Encephalopathy. Clin Lab Med 2002;22:849-62. |
*An abnormal signal in the posterior thalami on
T2- and diffusion-weighted images and fluid-attenuated inversion recovery
sequences on brain magnetic resonance imaging (MRI); in the appropriate
clinical context, this signal is highly specific for vCJD. |
Evidence for Relationship with BSE (Mad Cow Disease)
 |
 |
|
Percent distribution of non-iatrogenic UK vCJD
and US CJD deaths, by age group, 1995-2003. Larger Picture
(Courtesy
Ermias Belay) |
|
Since 1996, evidence has been increasing for a causal relationship between
ongoing outbreaks in Europe of a disease in cattle, called bovine spongiform
encephalopathy (BSE, or 'mad cow' disease), and vCJD. There is now strong
scientific evidence that the agent responsible for the outbreak of prion disease in
cows, BSE, is the same agent responsible for the outbreak of vCJD in humans. Both
disorders are invariably fatal brain diseases with unusually long incubation
periods measured in years, and are caused by an unconventional transmissible agent.
However, this evidence also suggests that the risk is low for having vCJD, even
after consumption of contaminated product. In 1996, because of the emergence of
vCJD in the United Kingdom, CDC enhanced its surveillance for CJD in the United
States.
 For more information about BSE and its occurrence in the United States and Canada, also see Bovine Spongiform
Encephalopathy
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