Bovine spongiform encephalopathy in cattle and variant Creutzfeldt Jakob Disease in humans are almost certainly two versions of the same disease.
Both conditions are linked to an abnormal version of a prion protein in the central nervous system. Doctors suspect that variant CJD is triggered by the ingestion of rogue prions from BSE infected meat.
So how do the rogue proteins cause disease? It seems they build up within the infected nerve cell, having changed shape and become resistant to normal cellular breakdown. Eventually the cell lining pops like a soap bubble, releasing rogue prions to cause further infection.
A small hole remains where the nerve cell used to be. Eventually, with a multiplication of this process, the brain develops the spongy appearance characteristic of both BSE and CJD.
We know from the old version of CJD that it can take up to 30 years for symptoms to develop. If the new variant was to show the same characteristics, then it may be 10 years or more before the full extent of infection becomes clear.
However, once symptoms begin, the progression of the disease is quite rapid. Complete dementia occurs within six months. The disorder can be fatal within seven months, with some people surviving for up to two years after diagnosis.
There is no easy test to confirm CJD. An EEG [a reading of electrical activity of the brain] will show characteristic changes, but the diagnosis will have already been strongly suspected based on the patient's history and the doctors physical examination.
Unfortunately, there is no known cure for what is a most unpleasant condition. Behaviour can become aggressive, requiring sedation and anti-psychotic medication.
There is a need to provide a safe environment, control agitated behaviour and to meet basic care needs, all of which may require hospitalisation or at least intensive support at home.
The symptoms of CJD follow the destruction of nerve cells in the brain and spinal cord and include:
personality change;
hallucinations;
muscle twitching and muscle stiffness;
changes in gait;
lack of co-ordination with stumbling and falls;
speech problems, including hard to understand speech and mumbling, and
dementia leading to profound confusion, disorientation and memory loss.
There is ongoing research into variant CJD, particularly to try and develop a non-invasive diagnostic test to pick up the disease before it causes symptoms.
Researchers are assessing the possibility of using a biopsy from the tonsils to achieve this, but the reality is we are still a long way from fully understanding or developing a cure for this fatal neurological condition.