Creutzfeldt–Jakob disease

Rare brain disease that causes progressive physical and mental deterioration, leading to death usually within a year of onset. It claims one person in every million and is universally fatal. The most common variant, vCJD has been linked with bovine spongiform encephalopathy (BSE), and there have also been occurrences in people treated with pituitary hormones derived from cows for growth or fertility problems.

CJD is one of a group of human and animal diseases known as transmissible spongiform encephalopathies (TSEs) since they are characterized by the appearance of spongy changes in brain tissue. It is believed that all the encephalopathies, including BSE in cattle and scrapie in sheep, are in effect the same disease. Research published by British pathologists in 1997 proved that vCJD is caused by the same agent that causes BSE, indicating that the disease had jumped species, from cattle to humans, during the 1990s BSE epidemic in the UK.

The American Red Cross announced in May 2001 that it would ban blood donations from anyone who had lived in the UK between 1980 and 1996 for three months, or in continental Europe for six months. The restriction, due to go into effect in September 2001, is an attempt to stop the spread of both vCJD and BSE through blood transfusions. The ban also extends to anyone who has had a blood transfusion in the UK. The organization said the ban would reduce the chance of blood reserves being infected by the diseases by more than 85%. It conceded that about 8% of its 6.5 million blood donors would no longer be able to give blood.

Like BSE, CJD is caused by the presence of an altered form of the brain prion protein PrP, that plays a role in sleep rhythms and in maintaining the brain cells called Purkinje cells. Once a small amount of the abnormal protein is present it begins to convert all the normal PrP. Similarities in the PrP of humans and bovines that are not found in other mammals were first discovered in 1996.

In 2001, Israeli scientists announced that they had devised a simple urine test to detect vCJD in live patients. The process was to undergo further reliability tests before being made widely available.

As well as vCJD, there are two other forms of the disease. Inherited CJD accounts for approximately 10–15% of cases. These congenital cases exhibit a mutation in the gene coding for PrPs. Sporadic CJD (sCJD) refers to those cases for which there is no known infectious source and no evidence of the disease being inherited. There are around 250 deaths from sCJD per year in the USA.

There is a second type of TSE affecting humans, kuru, which is found in Papua New Guinea.