Forced Cannibalism Spreads BSE – Prions

by Vincent Racaniello, PhD

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    00:00 Now there is also an illustrative example of a TSE in cows that gives us a lot of information on how the infection spreads and also has implications for human health, and that is bovine spongiform encephalopathy. Now in the European countries, particularly the UK, cows are fed protein supplements so that they grow more quickly as opposed to feeding them simply corn or grass and for many years the way this was prepared was to take other animals who died, including other cows, sheep and pigs, to grind them up and to make a meal for the cows that's basically ground-up meat from other animals. In the 1980s, all of a sudden there was an outbreak of a TSE in cows called bovine spongiform encephalopathy. And this is a result of feeding cows ground-up animals from animals who had scrapie, probably sheep, but maybe other cows as well who develop sporadic bovine spongiform encephalopathy. Now this outbreak really took off in the 1980s and we think that is a consequence of changing the way this protein supplement was prepared and given to the cows. In the 1970s the method of preparation of MBM meat and bone meal product was changed and we think that allowed the scrapie agent to survive and pass into cows. So there were hundreds of thousands of cows in the UK alone diagnosed with BSE, eventually that disease was stopped by changing the method of preparation of their feed. So mad cow disease, which is what this is also called, was eventually stopped. However, many people ate meat from these cows and acquired infection, so by humans eating meat from BSE affected cows, they developed the disease which is called variant Creutzfeldt-Jacob disease, this is a brand-new disease that is a neurological disease, but different symptomatically from the other TSEs of humans and it's acquired by eating BSE beef. Now when a cow has mad cow disease, it's quite clear, because they have trouble walking, they fall down, they're disoriented, however the incubation period is a few years. So cows are typically slaughtered before they reach the period where BSE is evident, and so that's why the prions got into the food supply and infected people. A few hundred people globally have developed variant Creutzfeldt-Jacob from eating BSE beef, but these cases still continue to appear, one or two sporadically here and there, because the incubation period can be up to 20 years. Just two years ago there was a case in Texas in the US of an individual who 14 years before had probably eaten beef in a country that received exports from the UK and he died of the disease, but he had no way of knowing that he was at risk.

    About the Lecture

    The lecture Forced Cannibalism Spreads BSE – Prions by Vincent Racaniello, PhD is from the course Microbiology: Introduction.

    Included Quiz Questions

    1. A few years
    2. 2 days
    3. 7 days
    4. A few weeks
    5. A few months
    1. Cow protein
    2. Water
    3. Cornmeal
    4. Hay
    5. Grass

    Author of lecture Forced Cannibalism Spreads BSE – Prions

     Vincent Racaniello, PhD

    Vincent Racaniello, PhD

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