BSE, also known as Mad Cow Disease, is a progressive fatal brain-wasting disease in cattle. The disease has an incubation period lasting 4 to 7 years, but ultimately is fatal for cattle within weeks of its onset. The concern is that Humans can get a disease called variant Creutzfeldt-Jakob Disease (vCJD) from eating meat from cattle infected by BSE.
This disease had been first identified in the United Kingdom in 1986, causing global awareness of the disease.
BSE is one of a number of Transmissible Spongiform Encephalopathies (TSEs), a family of diseases in humans and animals, which are characterized by sponge-like lesions in the brain. Other TSEs include Scrapie in sheep, Chronic Wasting Disease (CWD) in deer and elk and can have other variations in mink and even the feline species. The human version of BSE is called « variant Creutzfeldt-Jakob Disease » (vCJD), it is also a fatal brain-wasting disease and is classified as a Transmissible Spongiform Encephalopathy (TSE).
It is strongly believed that cattle in Britain developed BSE as a result of being fed commercial cattle feed made of rendered carcasses of dead sheep that were infected with Scrapie.
TRANSMISSION OF THE DISEASE
It is suggested that the transmission happens through commercial cattle feed prepared from carcasses of other infected ruminants (including cattle, deer, and elk) and from bits of waste cattle meat that are not fed to humans. Cows are naturally herbivores, meat being foreign to their digestive metabolism.
In Canada, only feed containing pig, horse, poultry and fish is allowed to be fed to cattle used for human consumption. Feed made out of other mammals has been outlawed since August 1997.
As per the Government of Alberta (Agriculture, Food and Rural Development Branch) BSE is not a contagious disease and cannot be transmitted animal to animal, or from consuming milk or dairy products.
Prions (Proteinaceous Infectious Particles) are the infectious agent responsible for the spread of BSE; they are abnormally structured forms of a host protein which are able to convert normal molecules of the protein into the abnormal structure. Prions cannot be deactivated because they are resistant to disinfectants and heat (for example cooking or sterilization).
The disease traveled from U.K. (where approximately 180,000 cases of BSE where confirmed until 2000) to the rest of the world by the exportation of over 200,000 tons of potentially contaminated feed. Cases of BSE have been confirmed in cattle in at least 21 countries. Also cattle were exported from UK before we were aware of the disease as it can take up to 6 years for the first symptoms to appear. As a precaution, since July 2003, the tissues that are more likely to contain BSE agent in cattle, such as skull, brain, spinal cord and a portion of the small intestine, are removed from the human food supply at the slaughterhouse; BSE is not transmitted through muscle meat or milk.
SYMPTOMS OF B.S.E
There might not be any symptoms appearing in infected cattle before 3 to 6 years after exposure to the disease. The Ministry of Agriculture, Food and Rural Development of Alberta explains that the symptoms are variable and progressive, here are a few of them: nervous or aggressive behaviour, abnormal posture and incoordination, weight loss and decreased milk production. The symptoms develop for up to 6 months, and then the animal dies. There is no cure for the disease.
Suspected cases of BSE must be reported to CFIA (Canadian Food Inspection Agency), there is no testing possible on live animals, the only way to diagnose the disease is through examining the dead animal's brain.
SYMPTOMS OF
VARIANT CREUTZFELDT-JAKOB
DISEASE (HUMAN B.S.E.)
The "variant Creutzfeldt-Jakob disease » (vCJD) was first recognized in the U.K. in 1996 and is believed to be transmitted from eating meat infected by BSE. It is a rare, degenerative and fatal brain disease, which damages brain cells and the spinal cord.
vCJD is often confused with CJD, or "Creutzfeldt-Jakob disease", another brain-wasting human TSE disease that causes sponge-like degeneration of the brain. However, CJD, which afflicts approximately one in a million people worldwide, is caused by a hereditary predisposition.
Some symptoms of vCJD include: dementia and loss of motor control; at an early stage patients usually experience psychiatric symptoms, which take the form of depression or, less often, a schizophrenia-like psychosis. Some unusual sensory symptoms also appear in half of the case (for example "stickiness" of the skin). Neurological degeneration, including unsteadiness, difficulty walking and involuntary movements, occurs as the illness progresses. By the time of death patients are completely immobile and mute.
The length of the incubation period is believed to be between 5 to 15 years.
TREATMENT
As per the BC Centre for Disease Control, there is currently no cure for vCJD; the patient must be supported with physical and occupational therapies. The patient will become confined to bed and must be fed by a tube.
AVOIDING vCJD
The Canadian Government has been undergoing strict measures to ensure that BSE and vCJD stay out of Canada by identifying eventual contaminated cows and removing them from human consumption. Feeding cattle out of cattle waste is now outlawed in Canada. In 2002, there has been one person infected with vCJD and it was found that this person had been travelling to the UK and eating beef several times in the 1980's. At the time of writing, there have been 5 cows infected with BSE in Canada; they all have been removed from the food chain by CFIA (Canadian Food Inspection Agency).
