Variant Creutzfeldt-Jakob Disease (vCJD)
- What is variant Creutzfeldt-Jakob disease (vCJD)? What is the history of vCJD? What causes vCJD?
- How does vCJD differ from classic CJD? What are vCJD symptoms and signs?
- Is variant CJD monitored in the U.S.?
- How many cases of vCJD have been reported in the U.S.?
- What is being done to prevent the spread of mad cow disease?
Variant CJD (vCJD) is a rare, degenerative, fatal brain disorder in humans. Although experience with this new disease is limited, evidence to date indicates that there has never been a case of vCJD transmitted through direct contact of one person with another. However, a case of probable transmission of vCJD through transfusion of blood components from an asymptomatic donor who subsequently developed the disease has been reported.
Since variant CJD was first reported in 1996, a total of 229 patients with this disease from 12 countries have been identified. As of June 2, 2014, variant CJD cases have been reported from the following countries: 177 from the United Kingdom, 27 from France, 5 from Spain, 4 from Ireland, 4 from the United States, 3 in the Netherlands, 2 in Portugal, 2 in Italy, 2 in Canada and one each from Japan, Saudi Arabia, and Taiwan. Two of the four U.S. cases, two of the four cases from Ireland, one of the two cases from Canada, and the single case from Japan were likely exposed to the BSE agent while residing in the United Kingdom.
There has never been a case of vCJD that did not have a history of exposure within a country where the cattle disease, BSE, was occurring.
It is believed that the persons who have developed vCJD became infected through their consumption of cattle products contaminated with the agent of BSE or in three cases, each reported from the United Kingdom, through receipt of blood from an asymptomatic, infected donor. There is no known treatment of vCJD and it is invariably fatal.
vCJD Differs from Classic CJD
This variant form of CJD should not be confused with the classic form of CJD that is endemic throughout the world, including the United States. There are several important differences between these two forms of the disease. The median age at death of patients with classic CJD in the United States, for example, is 68 years, and very few cases occur in persons under 30 years of age. In contrast, the median age at death of patients with vCJD in the United Kingdom is 28 years.
vCJD can be confirmed only through examination of brain tissue obtained by biopsy or at autopsy, but a "probable case" of vCJD can be diagnosed on the basis of clinical criteria developed in the United Kingdom.
The incubation period for vCJD is unknown because it is a new disease. However, it is likely that ultimately this incubation period will be measured in terms of many years or decades. In other words, whenever a person develops vCJD from consuming a BSE-contaminated product, he or she likely would have consumed that product many years or a decade or more earlier.
In contrast to classic CJD, vCJD in the United Kingdom predominantly affects younger people, has atypical clinical features, with prominent psychiatric or sensory symptoms at the time of clinical presentation and delayed onset of neurologic abnormalities, including ataxia within weeks or months, dementia and myoclonus late in the illness, a duration of illness of at least 6 months, and a diffusely abnormal non-diagnostic electroencephalogram.
The BSE epidemic in the United Kingdom reached its peak incidence in January 1993 at almost 1,000 new cases per week. The outbreak may have resulted from the feeding of scrapie-containing sheep meat-and-bone meal to cattle. There is strong evidence and general agreement that the outbreak was amplified by feeding rendered bovine meat-and-bone meal to young calves.
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