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May 2003 InformationFrequently Asked Questions about Variant Creutzfeldt-Jakob Disease (Variant CJD)
What is Creutzfeldt-Jakob Disease (CJD)?Creutzfeldt-Jakob Disease (CJD) is one of a small group of fatal diseases caused by infectious agents called prions. These attack the brain, killing cells and creating gaps in tissue. The disease is always fatal. There are two types of CJD: classical and variant. What are prions (in relation to variant CJD)?The agent that causes variant CJD is believed to be an abnormal form of a protein, known as a prion. Prions are normal cellular proteins that are present in many organs and tissues, including the brain, spinal cord and eyes of healthy humans and animals. The abnormal form of prion causes surrounding proteins to change their shape. The abnormal protein collects in central nervous tissue and by an unknown mechanism causes the nerve cells to die. This results in the characteristic holes in the brain tissue that can be seen under the microscope. How do people get variant CJD?Scientific evidence has linked variant CJD to eating contaminated beef products from animals infected with bovine spongiform encephalopathy (BSE) or "mad-cow disease." Processed meat products made from cows infected with BSE carry a high risk for transmitting the disease. What are the symptoms of variant CJD?Variant CJD symptoms include early psychiatric symptoms such as anxiety, depression, withdrawal and behavioural changes. Persistent pain or odd sensations in the face or limbs often develop. The disease then progresses to motor difficulties, involuntary movements and mental deterioration, often ending in a persistent vegetative state. The patient may live on average for about one year after the onset of symptoms. How is variant CJD diagnosed?Once a suspected case of variant CJD is reported to the Public Health Agency of Canada's CJD Surveillance System, the Department coordinates testing and works with case physicians and international experts to confirm the diagnosis. The diagnosis of variant CJD is very difficult, but brain scans, using magnetic resonance imaging (MRI), and tonsil biopsy are two types of tests used to establish a probable diagnosis. However, the final confirmation of variant CJD can only be done by examining brain tissue, generally after the patient has died. What treatment is available for a person who has variant CJD?At present, there is no cure or treatment to slow the progression of the disease. Is there a test to screen for variant CJD?No screening test is available for persons who may have been exposed to "mad-cow disease," hence there is no known method of detecting variant CJD before symptoms appear. Can variant CJD be transmitted from person to person by blood?Scientists haven't yet determined if variant CJD can be transmitted by blood. To date, there has never been a documented case of variant CJD transmitted through blood transfusion. However, evidence from experimental work in animals suggests that transmission of variant CJD by blood is theoretically possible. There have been two reported cases of transfusion-associated vCJD infection in UK. As a precaution, since 1999, Health Canada has implemented policies to protect Canadians from the theoretical risk of transmission of variant CJD through blood. Because people living in or visiting high risk countries for BSE could have been exposed to meat or meat products from cattle infected with BSE, donor screening questionnaires restrict individuals from giving blood if they have:
As well, people who have been exposed to medical devices used on a person subsequently diagnosed with variant CJD will be advised not to donate blood, tissues or organs. Can variant CJD be transmitted by casual contact or other means?Scientists do not believe that variant CJD can be transmitted through casual contact, like touching or kissing, or even intimate (sexual) contact with a person with the disease. Because variant CJD is a relatively new disease, how it is transmitted is not well understood. If the disease is transmitted in the same way as classical CJD, it may theoretically be possible for it to spread following exposure to medical devices used on a person subsequently diagnosed with variant CJD and through transplants. The tissues that are most infectious include the brain, spinal cord, pituitary gland and some parts of the eye. In variant CJD, other tissues such as the tonsils and appendix have also been found to be infective, in contrast with classical CJD. Can variant CJD be transmitted from a mother to her unborn child or through breast milk to her baby?Variant CJD is a relatively new disease, and knowledge about it is limited. However, to date there is no evidence that transmission of variant CJD from a mother to her unborn child or through breast milk has occurred in people with variant CJD. How many cases of variant CJD are there in Canada every year?In August, 2002 the first confirmed case of variant CJD was diagnosed in Canada. However, all the evidence indicates that, in this case, the individual was infected in the UK. There have been no subsequent cases of variant CJD in Canada. With respect to variant CJD what is the Government of Canada doing to protect the health of Canadians?The Public Health Agency of Canada works closely with other federal agencies and experts on CJD around the world to protect the health of Canadians. For example, when a suspected case is reported, the coordinator of the Public Health Agency of Canada's CJD Surveillance System works closely with the medical officers of health, case physician and hospital, the patient's family and experts in Canada, the United States and UK. Variant CJD has been linked to the consumption of meat or meat products from cattle infected with BSE. To this point Canada has been free of BSE in domestic cattle. For more information, see the Canadian Food Inspection Agency (CFIA) Web site. What advice does Public Health Agency of Canada provide to travelers to the UK and Europe ?The best available scientific evidence indicates that whole cuts of meat without the bone, such as steaks and roast, provide a lower level of risk of potential BSE contamination than do processed products such as sausages, burgers or pâtés. Higher risk items also include any other food products such as minced meats that might contain brain or spinal cord parts, since these are considered to have the highest concentration of prions in infected cattle and therefore carry the highest potential risk of transmission. It is important to note that BSE is unlike many other food-borne pathogens in that it cannot be killed simply by cooking the infected meat.
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Last Updated: 2003-07-09 |  |
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