KEY POINTS:
What is Creutzfeldt-Jakob disease (CJD)?
CJD is a fatal brain disease first reported by two German doctors (Creutzfeldt and Jakob) in 1920.
What causes CJD?
The disease is caused by prions - abnormal forms of protein which are extremely hardy and unable to be killed by normal sterilisation processes - attacking the central nervous system and invading the brain, causing dementia.
Areas in the brain attacked by the prions die and take on a holey, sponge-like appearance, or spongiform encephalopathy, when viewed under a microscope.
What are the symptoms?
In its early stages symptoms include minor lapses of memory, mood changes and loss of interest.
As the disease develops the infected person becomes increasingly clumsy and begins slurring their speech.
As CJD progresses, the person loses more control of their movements until eventually they have no ability to move or speak.
At this point they are no longer aware of their surroundings or disabilities and need full nursing care.
Most people infected by CJD will be dead within six months of the first symptoms, usually dying of pneumonia.
There is no test for CJD and can only be confirmed by biopsy on death. The disease can lie dormant in the brain for many years.
What's the difference between CJD and "mad cow disease"?
Bovine spongiform encephalopathy (BSE) is a form of prion disease affecting cattle. It was discovered the UK in 1986.
In 1996 a new form of CJD, called variant CJD (vCJD), had been discovered and evidence pointed to it linked to BSE affecting cattle.
It is probable that victims caught vCJD by eating the infected beef products.
Britain had banned cattle brain tissue and spinal cords from use in human food products in 1989, but an official government study concluded those with vCJD had been exposed to the infected food before that date.
How do you catch CJD?
There are four forms of CJD - vCJD, sporadic, familial and iotrogenic.
As discussed, vCJD is probably contracted from eating infected beef tissue.
Sporadic CJD (also called classical CJD) results in the rapid onset of dementia, mainly in those over the age of 50, and the cause is unknown.
Familial CJD is an inherited form of the disease-affecting people at an earlier age than the classic form, with a longer period of dementia.
Iatrogenic CJD is contracted after contact with tissue from an affected person, including corneal transplants, grafts or using growth hormones.
The disease may also be contracted from neurosurgical instruments previously in contact with infected tissue.
But aren't surgical instruments sterilised?
Yes, but the hardy prion proteins stick to metal and can survive up to 10 routine sterilisations.
In 2004, the Victorian State Government in Australia spent A$3 million on new sterilisation equipment for seven public hospitals following a CJD contamination scare.
After instruments used during brain surgery on a man who later died of CJD were used for a further 20 months, Royal Melbourne Hospital threw out 15,000 surgical instruments and had 300,000 other surgical tools re-sterilised under tougher conditions.
How many people die of CJD?
One in one million people die every year from the sporadic form of CJD, which equates to three or four people in New Zealand.
