Another study published in 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 ; 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 ; 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 ; These cases have all been diagnosed since France has reported six cases.
In the UK the majority of cases of vCJD were born before , and it is very unlikely that they received vaccines contaminated with the BSE agent Vaccine ; Epidemiological evidence to date suggests that these cases of vCJD acquired the disease from eating beef products containing the BSE agent after To date February there have been reported cases of vCJD.
Of these, have occurred in the UK. What is BSE? What causes BSE? Where is the BSE agent found in cattle? Which countries have reported BSE?
How was BSE spread? What has the British government done in response to the BSE epidemic? How is the BSE agent detected? Does BSE or a similar disease occur in humans? Typically, CJD patients are over 63 years old.
BSE attacks the brain and central nervous system of the animal and eventually causes death. This means that it usually takes four to six years for cattle infected with BSE to show signs of the disease, such as disorientation, clumsiness and, occasionally, aggressive behaviour towards other animals and humans.
BSE was first confirmed in cattle in the UK in The first case in Ireland was confirmed in , when there were 15 cases confirmed. MBM is produced in a process called rendering. This is where otherwise unused animal products are taken from the carcass and are cooked for a long time to produce MBM.
MBM was incorporated into cattle feed until it was banned in the s. Experiments have shown that cattle can contract BSE if they are fed infected brain tissue. This supports the idea that BSE was transmitted to cattle through their animal feed. The practice of feeding MBM to cattle has been banned in Ireland since in Controls on MBM were strengthened in BSE only develops in cattle, but it belongs to a family of prion diseases, several of which can affect humans.
Since August , the FDA has not allowed most parts from cows and certain other animals to be used to make food that is fed to cows. This protects healthy cows from getting BSE by making sure that the food they eat is not contaminated with the abnormal prion. Certain high-risk cow parts are not allowed to be used to make any animal feed, including pet food.
This prevents all animal feed from being accidentally contaminated with the abnormal prion. High-risk cow parts are those parts of the cow that have the highest chance of being infected with the abnormal prion, such as the brains and spinal cords from cows that are 30 months of age or older. By keeping the food that is fed to cows safe, the FDA is protecting people by making sure that the food they eat comes from healthy cows.
The FDA also works with the U. The USDA also makes sure that high-risk cow parts, such as the brains and spinal cords, and cows that are unable to walk or that show other signs of disease are not used to make food for people. Only six cows with BSE have been found in the U. The first case was reported in and the most recent case was found in August It is worth noting that there are two types of BSE, classical and atypical. Classical is caused by contaminated feed fed to cows.
Atypical is rarer and happens spontaneously, usually in cows 8-years-old or older. Of the six U. But in rare cases they may get a human form of mad cow disease called variant Creutzfeldt-Jakob disease vCJD , which is fatal. This can happen if you eat nerve tissue the brain and spinal cord of cattle that were infected with mad cow disease. Over time, vCJD destroys the brain and spinal cord. There is no evidence that people can get mad cow disease or vCJD from eating muscle meat—which is used for ground beef, roasts, and steaks—or from consuming milk or milk products.
People with vCJD cannot spread it to others through casual contact. People who have spent a lot of time at least 3 months in places where mad cow disease has been found are not allowed to give blood in Canada or the United States.
Experts are not sure what causes mad cow disease or vCJD. The leading theory is that the disease is caused by infectious proteins called prions say "PREE-ons". In affected cows, these proteins are found in the brain, spinal cord, and small intestine. There is no proof that prions are found in muscle meat such as steak or in milk. When a cow is slaughtered, parts of it are used for human food and other parts are used in animal feed.
If an infected cow is slaughtered and its nerve tissue is used in cattle feed, other cows can become infected. People can get vCJD if they eat the brain or spinal cord tissue of infected cattle. The first case of vCJD was reported in Since then, there have been a few cases of vCJD reported in the world.
No meat from these cows entered the human food supply. It is fatal.
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