Creutzfeldt-Jakob Disease (CJD)
Prepared by the Centre for Neurodegenerative Diseases,
University of Toronto
Is vCJD in Canada?
To date, there has been one case of variant CJD reported in Canada. Health
Canada has confirmed that this person lived and traveled extensively throughout the
United Kingdom during the height of the BSE (Mad Cow) epidemic and had eaten
beef in the U.K. during that period. There is no indication the individual contracted
the disease anywhere other than the United Kingdom.
To ensure that any cases of vCJD are detected immediately Health Canada has
set up a CJD Surveillance System, which began in 1998. The Canadian surveillance
unit screens approximately 90 samples that are suspected of having sCJD each
year. Of these between 30 and 35 cases are diagnosed as sporadic CJD. These
numbers are consistent with the one person per million worldwide occurrence of
sCJD per year.
What is CJD?
CJD is a rare and fatal brain disease in humans. The symptoms include
progressive loss of mental functioning and loss of coordination.
What causes CJD?
CJD is a member of a disease group known as transmissible spongiform
encephalopathies (TSE). TSEs are fatal diseases of the central nervous system
affecting both humans and animals. Scrapie in sheep, chronic wasting disease and
BSE (mad cow disease) are examples of TSEs in the animal population.
Although it is not known what causes these diseases, the presence of an
infectious agent known as the ‘prion’ (proteinaceous infectious particle) is believed to
be responsible for a conversion of normal host proteins in the central nervous
system. This conversion is the likely cause for a loss of brain cells resulting in the
‘spongy’ appearance of the brain tissue.
Are prion diseases in humans linked to ‘mad cow disease’ (BSE)?
There are actually several different forms of prion diseases affecting humans.
The different types are categorized according to how someone would acquire the
Sporadic CJD: The most c