VARIANT CJD (vCJD)
Variant CJD (vCJD) is the human form of bovine spongiform encephalopathy (BSE) sometimes called "Mad Cow" Disease.
Variant CJD, first recognised in 1996 following the 1st death in the UK in 1994, relates to the consumption of BSE contaminated products.
vCJD is the only form of CJD where there is evidence that transmission can occur through exposure to blood and blood products.
Variant CJD is clinically quite different to classical CJD.
BSE has NOT been found in Australian livestock and to date there have been no reported cases of vCJD in Australia.
What is variant CJD and how does it differ from other forms of CJD?
Variant Creutzfeldt-Jakob disease (vCJD) is the most recently recognised of the human prion diseases or transmissible spongiform encepalopathies (TSE’s). This new disease is often mistakenly referred to as “Mad Cow" Disease, inadvertently emphasising the animal origin of vCJD. Variant CJD is probably related to the consumption of bovine spongiform encephalopathy (BSE)-contaminated meat products following the epidemic of BSE in United Kingdom cattle during the 1980 and 1990s.
The first deaths from vCJD occurred in England in 1995. Public recognition came following reporting of the first 10 identified cases in 1996. Variant CJD has not been seen in Australia, and is clinically quite different to classical Creutzfeldt-Jakob disease (cCJD). Even the term classical CJD includes a range of different forms of CJD, based on how the disease has been acquired. Sporadic CJD (sCJD) is the naturally occurring form of the disease and accounts for up to 90% of all cases of CJD. There are also familial forms (genetically inherited TSE’s), and medically acquired disease (including recipients of human pituitary extract hormone and dura mater grafts following neurosurgery). Kuru, another human TSE, has not been seen outside of the Eastern Highlands of Papua New Guinea.
Variant CJD is distinguished from other human TSE, particularly from sCJD, by;
- a predominantly psychiatric presentation,
- a younger age onset (on average 29 years of age),
- a longer duration of illness (average duration 14 months),
- investigation results, and
- distinctive pathological changes to the brain
Recent changes to blood donor guidelines within Australia, New Zealand, Canada and the USA have been in response to the differing characteristics of vCJD and uncertainty regarding potential routes of transmission and infectivity.
Definitive diagnosis of all TSEs relies on examination of the brain at autopsy. The brains of patients with either sCJD or vCJD contain abnormal forms of prion protein. This abnormal form of the protein is linked directly to TSEs and constitutes an excellent marker for this group of diseases. The examination of the vCJD brain shows widespread deposits of abnormal prion protein, called florid plaques. This form of plaque is not seen in sCJD. Variant CJD can also be detected in lymphatic tissue (spleen, tonsils and lymph nodes), unlike sCJD.
The early symptoms of vCJD are generally psychiatric. These include depression, anxiety, apathy, withdrawal and delusions. Most vCJD patients are usually considered to be suffering from purely psychiatric disorders during the early phase of the illness. The symptoms are persistent and patients are usually prescribed psychiatric medications and seen by psychiatrists. Definite neurological symptoms do not generally develop until after approximately six months, with memory impairment, persistent sensory symptoms (such as tingling, burning or pain), ataxia (balance and walking disturbances), involuntary movements and visual disturbances all frequently seen. The illness progresses to include a dementia and a state of complete helplessness. Death on average occurs after 14 months (with a range of eight to thirty-eight months) from disease onset and at an average age of 29 years (ages of those dying from vCJD have ranged from 14 to 74 years of age).
We wish to thank the department of Health and Ageing for the provision of this article.
How Australia will respond to the first case of variant CJD - Read article here
© Copyright CJD Support Group Pty Ltd 2005-2009