This Web site offers consumers information about Creutzfeldt-Jakob Disease in an attempt to debunk Mad Cow Disease myths about the occurrence of Mad Cow Disease in humans. Below are some of the most frequently asked questions and answers.

What is the new variant form of CJD that the experts in the United Kingdom believe might be related to the BSE outbreak in cattle?

In contrast to the classic form of CJD, the new variant or variant form (vCJD) in the United Kingdom and France affects younger persons (average age at onset: 26 years), and has different clinical features from CJD. People with vCJD begin with serious psychiatric problems or problems with their senses (ears, eyes or smell). This first set of symptoms is followed weeks or months later by poor muscle coordination, muscle spasms, and mental confusion. The illness lasts for at least 6 months, and on average people with vCJD die approximately 13 months after their symptoms begin. When patients’ brains are examined by autopsy, there are clear changes in brain tissue structure, including many “spongiform,” or open spongy-looking areas, abnormal clumps of prion protein called plaques, and other areas with less prominent accumulations of abnormal prion protein.

Exactly how does this newly recognized variant of CJD differ from classical CJD?

In 1996 the Spongiform Encephalopathy Advisory Committee (SEAC) of the UK announced the identification of 10 cases of variant CJD (vCJD, Lancet, 1996, 347: 921-25). Since then over 100 people have died of vCJD in the UK. The following features describe how vCJD cases differ from the sporadic or classical form of CJD (Lancet, 1996, 347: 921-25, Rev.Med.Virol. 2002;12: 143-50):

• The affected individuals were much younger than the classical CJD patient. Typically, CJD patients are over 63 years old. The average patient with vCJD is 26 years old; patients ranged from 12-74 years old.

• The course of vCJD averaged 13 months (range 6-40 months). Classical CJD cases average a 4 month duration.

• In the vCJD cases, electroencephalographic (EEG) electrical activity in the brain, while abnormal (slowed), was not typical of classical CJD, which often has periodic bursts of increased electrical activity.

• Although changes in brain tissue structure of patients with vCJD were recognizable as CJD, the pattern was different from classical CJD, with large aggregates of prion protein plaques often surrounded by vacuoles.

How did people get this new variant of CJD?

On March 20, 1996 a statement from the Spongiform Encephalopathy Advisory Committee (SEAC) of the United Kingdom indicated concern that before November 1989, when inclusion of certain cow and sheep by-products in human food was banned, the BSE agent may have been transmitted to people through contaminated food products. The SEAC said that food might account for the 10 vCJD cases described in 1996 (Lancet 1996; 347:921-5). The specific foods, if any that may be associated with the transmission of this agent from cattle to humans are unknown. However, the SEAC has indicated that milk and milk products are unlikely to pose any risk for human exposure to the BSE agent.

What is the evidence directly linking this newly recognized variant of CJD to BSE exposure?

There is strong epidemiologic and laboratory evidence suggesting that new variant CJD (vCJD) and BSE are caused by the same infectious agent. For instance, all cases of confirmed vCJD have occurred in people who have lived in geographic areas which have had BSE cases. The majority of cases of vCJD have occurred in the UK, which has had the largest number of cases of BSE in cattle. In addition, the time interval or “incubation period” between the most likely period for the initial exposure of the population to potentially BSE-contaminated food (1984-1986) and onset of initial vCJD cases (1994-1996), about 10 years, is similar to the known time intervals between exposure to the classical CJD agent and the development of CJD. An experimental study reported in June 1996, showed that three cynomolgus macaque monkeys that were injected with brain tissue from cattle with BSE later developed symptoms and changes in brain tissue that were strikingly similar to vCJD (Nature 1996;381:743-4). Another study published in 1996 showed that prion proteins obtained from 10 vCJD patients and BSE-infected animals had molecular characteristics that were similar to each other but distinct from prion proteins obtained from patients with classical CJD (Nature 1996;383:685-90). Furthermore, results of an ongoing experimental study involving injection of a panel of various strains of mice with the agent that causes BSE and vCJD suggested that these agents cause a similar disease in mice (Nature 1997;389:498-501). Histological analysis of mouse brains from this study showed no significant differences in the neuropathological changes observed in the BSE and vCJD-infected mice (Neuropathology and Applied Neurobiology 2003; 29:262-272). A study using transgenic mice (PNAS 1999; 96:15137-15242) also supports the hypothesis that the BSE agent from cattle causes vCJD.

How many cases of variant CJD have occurred?

Cases of variant CJD are very rare, and most have occurred in the United Kingdom. Information provided by the UK Creutzfeldt-Jakob Disease Surveillance Unit (February, 2004, www.cjd.ed.ac.uk/figures.htm) indicates that there have been 146 cases of definite and probable vCJD in the United Kingdom. These cases have all been diagnosed since 1995. France has reported six cases. The Republic of Ireland, Italy, Canada and the US have each reported one case. The cases in Ireland, Canada and the US each occurred in individuals who had spent several years in the UK.

Could anyone in Europe diagnosed with the newly recognized variant of CJD (vCJD) have acquired this from vaccines?

In the UK the majority of cases of vCJD were born before 1980, and it is very unlikely that they received vaccines contaminated with the BSE agent (Vaccine 2000; 19:409-410). Surveillance of vCJD in the UK has identified three “risk factors,” or characteristics common to most if not all of the people who had vCJD: i) residence in the UK; ii) a particular genetic susceptibility (met/met homozygosity at codon 129 of the PrP gene); and iii) age. Epidemiological evidence to date suggests that these cases of vCJD acquired the disease from eating beef products containing the BSE agent after 1980. To date (February 2004) there have been 156 reported cases of vCJD. Of these, 146 have occurred in the UK. Six cases of vCJD have been diagnosed in France, and one each in Canada, Ireland, Italy and the US. The cases in Canada, Ireland and the US each occurred in individuals who had spent several years in the UK.