Variant Creutzfeldt-Jakob

Variant Creutzfeldt-Jakob

Variant Creutzfeldt-Jakob disease is a prion related disorder, only known to exist since 1995.  VCJD falls into a group of different neurodegenerative disorders which are known to affect both humans and animals.  Bovine spongiform encephalopathy or mad cow disease affects cattle, while scrapie is the name given to the disease that affects sheep.  In deer, a similar disorder is called Chronic Wasting Disease.  In humans, there are a few different but related conditions.  Kuru is a prion disease identified in a native New Guinea tribe.  It was found to be transmitted through cannibalism, especially through the consumption of nervous tissue.

Stanley Prusiner was the first scientist to identify a disease causing protein, finding them while doing research on sheep that were infected with scrapie.  An interesting thing about his work is that he discovered and named prions in 1982, but his research wasn’t accepted for many years.  His recognition was due to the development of variant Creutzfeldt-Jakob disease, in which his studies were used to identify it.  Prusiner won the Nobel Prize in 1997 for his work with infectious proteins.

Prion diseases are caused by an infectious protein that leads to an abnormal shape change of cellular proteins in nervous tissue.  These new proteins cause a chain reaction in which more and more proteins become infected and changed.  When enough of these abnormal proteins are built up in the central nervous system, they begin to cause damage.  Eventually, enough damage will cause a rapid decline in brain function and death.  

Creutzfeldt-Jakob disease has a number of variations.  Variant CJD is transmitted to humans through the consumption of beef infected with bovine spongiform encephalopathy or BSE. Another form caused by a genetic mutation that can be passed to offspring is familial CJD.  Iatrogenic CJD is passed by different medical procedures.  Some of the causes are contaminated medical equipment or transplanted biological material such as blood or hormones being infected.  Finally, the most common form is sporadic CJD.  This form counts for around 85% of all cases of CJD.  (CDC) sCJD is similar to an advanced form of dementia, in which the brain and its functions degenerate quickly.  

There are commonalities between all types of CJD.  The first is the degeneration of nervous tissue, especially in the brain.  Eventually this breakdown will cause death, as these diseases are always fatal.  Also, CJD is known to have long incubation periods in which no signs or symptoms are present.  Lastly, although symptoms are shown that are similar to dementia, there is no guaranteed way to diagnose someone with CJD.  Tests such as an MRI can narrow down the possibilities, but the only way to identify the disease is through biopsy and testing of nervous tissue.  (Morgan) This is usually done post mortem.