Jacquelyn Yerian

General Microbiology
18 May 2011

Left: nvCJD brain Right: Normal brain

Though classified as a bovine disease, Bovine Spongiform Encephalopathy is transmissible to humans
causing what is known as new variant Creutzfeldt - Jakob disease, or nvCJD. The disease is contracted
when humans eat food products that have been exposed to or contaminated with the brain, spinal cord, or
digestive remains of cows previously infected with BSE. This encourages the growth of prions, which are
misfolded proteins. These proteins promote the refolding of native proteins into a diseased state,
which inherently disrupts cell function and causes cell death. The symptoms of this disease in
humans mirror the symptoms of cows when prions permeate the brain and cause decay, dementia,
loss of motor function, and ultimately death.


Healthy BSE Free cows from my hometown in Tracy, CA.

I come from a small town where it is not uncommon for families to personally own cattle. My little country home
alone provides a home for seven cattle and counting. I am very familiar with the behaviors displayed by cows that
would be classified as normal, so I feel as though I would be a good judge of anything out of the ordinary. Because
my family does not feed our livestock remains of sheep infected with scrapie disease, which is thought to cause BSE,
I am not worried about my animals contracting Mad Cow Disease. Therefore, I am not worried about contracting nvCJD
myself, because I rarely consume beef that is not home grown on my property. However, I do think that it is important that a larger mass of the public be aware of the negative effects associated with providing improper nutrition when raising cattle, because nvCJD is not only devastatingly fatal, but preventable as well.

Another reason that I am interested in the topic is due to my familiarity with prions. A few months back, I went to the
first annual lecture series on neurodegenerative diseases at the Buck Institute in Novato, CA. The keynote speaker,
Stanley B. Prusiner, M.D. received the Nobel Prize for his research towards the discovery of prions- the cause of many neurodegenerative diseases, including BSE and nvCJD (Brown, 2010). Having attended the lecture series along with currently studying microbiology, I was able to appreciate his findings on a whole new level.


Stanley B. Prusiner

New variant Creutzfeldt - Jakob Disease in humans is thought to be caused by prions, which encourage conformational changes of proteins. This evolutionary process is problematic because it promotes the refolding of native proteins into the diseased state, or in other words - from alpha-helices into beta-pleated sheets (Tortora, 2010). When these amyloid proteins accumulate in organs and tissues, the misfolded hydrophobic proteins are not always dissolved by proteolysis. When the exponential increase of these diseased conformations of proteins occurs, the cells are no longer able to function properly, and eventually die off (Zerr, 2011).
Transformation of Alpha-Helices into Beta-Pleated Sheets

Once a prion is transmitted, it begins the “self-sustaining feedback loop” which causes the disease to progress (Ghetti, 1999). As the diseased proteins die off, it causes the spongy deterioration of the brain and spinal cord, leading to an array of symptoms that are incurable, irreversible, and eventually fatal. Patients diagnosed with nvCJD are usually diagnosed at a young age, with the disease lasting approximately 12-14 months. Symptoms affect both the physical and mental capacity of patients leading to rapidly progressing dementia, irritability, mood swings, muscle jerks, loss of sight, and eventually the inability to speak along with the loss of all motor function, resulting in death (Zeidler, 1997).

The number of CJD cases significantly outnumbers the number of vCJD cases, which suggests that inherited forms of the disease are far more likely to occur, and the precautions implemented to track and prevent vCJD are successful.


Donors Giving Blood at a Red Cross blood drive
Donors Giving Blood at a Red Cross blood drive
Unlike other forms of Creutzfeldt-Jakob Disease, new variant CJD is preventable if necessary precautions are taken. Because it is caused by the ingestion of contaminated beef products, the first obvious step towards prevention is to not consume contaminated meat (Brown, 2004). "In 1997, the FDA published a final regulation designed to prevent the spread of BSE through animal feed" (Division of Compliance, 2011).Another precaution that has been taken is in the hands of health professionals and blood banks. New regulations have been set in place to ensure that the blood received at blood banks not be contaminated with blood from donors who either have the disease, or come from countries with a history of the bovine strain of the disease (Ironside, 2009). "Donors who have resided for three or more months in countries with frequent instances of Bovine Spongiform Encephalopathy" are unable to give blood (Brown, 2008).



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  2. Brown, Paul. “The Risk of Bovine Spongiform Encephalopathy ("Mad Cow Disease") to Human health”. Published online in JAMA1008-1011 (2008).
  3. Brown, Paul. et al. "Ultrastructural Characteristics (or Evaluation) of Creutzfeldt-Jakob Disease and Other Human Transmissible Spongiform Encephalopathies or Prion Diseases. "Ultrastructural Pathology 34.6 (2010): 351-361.Academic Search Premier. EBSCO. Web. 17 May 2011.
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  6. Zerr, Inga. et al. "Amyloid-β 1-42 Levels are Modified by Apolipoprotein E4 in Creutzfeldt-Jakob Disease in a Similar Manner as in Alzheimer's disease."Journal of Alzheimer's Disease23.4 (2011): 717-726.Academic Search Premier. EBSCO. Web. 13 May 2011.
  7. Ironside, J.W. et al. "Panencephalopathic Creutzfeldt–Jakob disease in the Netherlands and the UK: clinical and pathological characteristics of nine patients."Neuropathology & Applied Neurobiology35.3 (2009): 272-282.Academic Search Premier. EBSCO. Web. 5 May 2011.
  8. Tortora, Garard. Funke, Berdell. Case, Christine Microbiology. 10th ed. U.S.: Pearson Education, 2010. 317. Print.
  9. Zeidler, M. “New Variant Creutzfeldt-Jakob Disease: Psychiatric Features”. The Lancet 350, 897-968 (1997).