Creutzfeldt-Jakob disease (CJD) is considered to be the human form of "mad cow" disease (bovine spongiform encephalopathy; the form in sheep is known as scrapie). It causes irreparable brain damage, impairs an individual's ability to think, see, speak and move, and eventually leads to death. Muscles go into spasm, becoming rigid and jerky. Balance is lost. The dementia that develops mimics Alzheimer's disease, a related disorder that is not classified as a spongiform disease. For many years it was regarded as a very rare disease of the elderly, almost always occurring after a long incubation period.
It is thought that the infective material may originate in meat products from infected cows and sheep (particularly brains and spinal cords) although there is is only circumstantial evidence of this. The overwhelming majority of CJD cases occur sporadically and with no clue as to how they are transmitted. There are fears with as yet no factual basis that CJD could spread via blood transfusion.
The incidence of CJD s about 1 person per million. Three groups have a higher incidence than that: those treated with contaminated growth hormone in the 1980's; those who have had brain surgery involving tissue patching with duramater from cadavers; and those who have CJD in the family.
In 1994, it was reported that at least two young British women have CJD and two middle-aged dairy farmers died of the disease within the previous 12 months. One UK doctor believes that consumption, even in small doses, is cumulative and predicts that at least one beef eater in 10 may develop CJD unless humans develop immunity.
Up to March 1996, ten cases of a new variant of Creutzfeldt-Jakob disease had been reported in the United Kingdom, linked to exposure to the agent of bovine spongiform encephalopathy in meat products. Cases of bovine spongiform encephalopathy have declined since 1993, and the epidemic of bovine spongiform encephalopathy is expected to disappear in the United Kingdom by the year 2001. By 1999, 46 people had died of the disease.