Diseases are
always a hot topic in every branch of science. From the early times, when
people or animals got sick, there was some scientist wanting to know why and
how. The transfer of diseases from animals to humans is not anything new. At
one point in history animals lived in very close quarters with their humans and
that is what sparked many diseases in humans.
The most
known diseases like the bubonic plague or rabies are studied and researched by
bacteriologist or epidemiologist. But what about the rare diseases that are not
transferred through direct contact or a bite? There are diseases that be contracted
by a misfolded protein. This is where the study of diseases at a molecular
level comes in handy.
The study of
prion diseases use to be something so rare, no one really thought it needed to
be studied in depth. In 1730 the first prion disease or transmissible spongiform encephalopathies (TSE's) was discovered
in sheep and goats. This prion disease is known as Scrapie. Other prion
diseases were soon discovered in other animals as time went on. The most
popular prion disease that everyone talks about is, bovine spongiform
encephalopathy (BSE) or more commonly referred to as “mad cow disease”.
So, what is
a prion disease? What exactly is mad cow disease? How are humans affected?
To simply
put it, a prion is an infectious protein. The prion protein normally gets
broken down by enzymes. However, when prions misfold and become an abnormal
shape, they cannot be broken down. When one prion protein misfolds, it causes a
chain reaction of other prions misfolding thus causing an accumulation of these
infectious proteins. These abnormal prions usually build up in the brain of the
affected animals, although abnormal prions have been found in other organs.
Normally this build up causes neurological issues. Once the effected subject
shows signs of neurological damage, it is a quick down fall to death from
there.
There are
three “types” of prion diseases. They include; sporadic, inherited, and
acquired prion disease. Sporadic prion disease is also known as
Creutzfeldt-Jakob disease (CJD), this type of prion disease occurs randomly in
the population. Inherited prion disease occurs due to a genetic mutation. Finally,
an acquired prion disease is a result of a surgical procedure or by consuming
previously infected meat.
The
consumption of meat from a cow who had these infectious prions is where the fun
subject of mad cow disease begins.
Bovine
Spongiform Encephalopathy (BSE) is the cow version of the previously mentioned transmissible spongiform encephalopathies. BSE was first
discovered in the UK 1986. It is believed that the first case was caused by
farmers feeding their herds carcasses of scrapie-infected sheep or cattle with
abnormal prions. After consumption of the carcasses, it was not long before
farmers started noticing their herds of cattle begin to go mad. They became
violent and began to stumble and eventually lost the ability to walk and
eventually died.
All
of these dead cows couldn’t go to waste, some was made into food for the cows
and the cycle continued. However, some cows went to humans, and many people
consumed the meat of these infected cows.
BSE
has been linked to a brain disease in humans called variant Creutzfeldt-Jakob
disease (vCJD). vCJD is one of the many types of transmissible spongiform
encephalopathies. vCJD has been linked to people who have consumed meat a cow
that has BSE. However, by the time vCJD is found, it is too late as the brain
has already been destroyed. The first case was reported in 1996 in the UK. All
other cases reported were in areas that also had a BSE outbreak. Through many
experiments it is safe to say that there is a direct correlation between BSE
and vCJD.
There
is so much to learn from diseases, I believe that studying on a molecular
level, is one step closer to finding more cures and catching things quicker.
Links:
I think this was an excellent overview of prions and how they are transmitted! I didn't know that prion diseases had been recorded as early as the 1730's.
ReplyDeleteWe learned about a little about prions in microbiology, but it's nice to know more about it and how exactly they are transmitted. Also, I never would have thought that the infected cows would still be eaten.
ReplyDeleteI would like to first say that I enjoyed reading your post mainly because of your style of writing. Your post was extremely insightful and very interesting. Dr. Lynne touched on the subject of Mad Cow's disease in microbiology so I have heard about how prions can causes this disease in the past. However, I did not know that farmers were feeding their infected cows to humans.
ReplyDeleteI have always found mad cow disease to be so interesting. Did you know there is another prion disease called Kuru that would spread among people within a tribe? This happened because they would have rituals that they would do after people had died and in these rituals they would actually eat the brains of the deceased. This in terms caused the people that had eaten the contaminated brain to contract the disease as well. It goes hand in hand with the mad cow disease considering it is contracted from eating infected meat that the farmers actually didn't know was infected. It's scary to think of how many diseases are out there that we don't actually know about.
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteI really enjoyed reading your post because I always knew just the basics of Mad Cow Disease, but not into more detail. It was insightful how you included how it all started and then effected humans in the long run. I agree with you on the fact there is so much more to learn about diseases, but so far advances in molecular biology has helped scientist a lot and I can not wait to see how much further it goes. It is crazy that the farmers did not think that feeding the dead cows to the healthy ones would not carry was made them sick in the first place.
ReplyDeleteNice start. One small suggestion; larger text with less space between lines would be easier to read. Also, some of the text is black. On dark gray, it is really hard to read.
ReplyDelete