Mad Cow Disease andVariant
Creutzfeldt-Jakob Disease
Understanding the Brain:The Neurobiology of
Everyday Life
Final Project by Amalia Martínez Avalos

MAD COW DISEASE
 Medically known as Bovine Spongiform Encephalopathy (BSE), affects
the central nervous system (CNS) of cattle
 Belongs to a group of Transmissible Spongiform Encephalopathies
(TSE).
 This is a group of neurodegenerative disorders that affect animals
and humans
 The name Mad Cow Disease refers to the signs of infected cattle:
◦ staggering,
◦ drooling,
◦ signs of fear,
◦ grinding of teeth,
◦ aggression toward other animals

Mad Cow Disease
 The disease was first diagnosed in the
United Kingdom in 1986.
 Infected adult cattle may develop signs of
the disease slowly (2 to 8 years):
◦ change in attitude and behavior
◦ gradual uncoordinated movements
◦ trouble standing and walking
◦ Weight loss
◦ Eventually the animal dies

How cattle develop Mad Cow
Disease
 Feed is the major route for transmission
among cattle
 When cattle are feed with products made
from other cattle or sheep, they are
recycling diseased animal protein in feed
containing meat and bone meal, thus
causing the disease in cattle.

Mad Cow Disease: Zoonotic
importance
 A human version of Mad Cow Disease
called variant Creutzfeldt-Jakob disease
(vCJD) is believed to be caused by eating
beef infected with bovine spongiform
encephalopathy (BSE), products
contaminated with central nervous
system tissue

Creutzfeldt-Jakob Disease
(CJD)
 It is important to clarify the differences between
variant CJD and another form of the disease,
referred to as classic or sporadic CJD.
 Classic CJD is not linked to eating nerve tissue from
mad cow disease-affected cattle and it may be caused
by;
 SPORADICALLY. CJD that occurs without explanation is
termed spontaneous CJD or sporadic CJD and accounts for the
majority of cases.
 INHERITANCE. In the United States, about 5 to 10 percent of
people with CJD have a family history of the disease.
 IATROGENIC. A small number of people have developed CJD
after being exposed to infected human tissue during a medical
procedure, such as a cornea or skin transplant
 Classic CJD most commonly affects people over 65 and is usually
fatal within six months from onset of symptoms

Variant Creutzfeldt-Jakob
Disease: characteristics
Difference between variantCJD and classic
CJD
 younger age of onset, (lower than 29 years vs.65
yeears in classicCJD classic)
 lack of characteristic EEG findings,
 longer course of disease,
 and more extensive spongiform change
with plaques in the brains of affected
persons.

Causitative agent
 Researchers believe that the infectious
agent that causes mad cow disease and
andVariant Creutzfeldt-Jakob
Disease is an abnormal version of a
protein normally found on cell surfaces,
called a prion
 For reasons still unknown, this protein
becomes altered and destroys nervous
system tissue (brain and spinal cord).

PRION
 Is a type of protein
 “prion” : neologism deriving from the words “protein”
and “infection”
 Prion proteins occur in:
◦ a normal form, which is a harmless protein found in the
body’s cells
◦ an infectious form, which causes disease
◦ Both forms of the prion protein have the same sequence
of amino acids
◦ the infectious form of the protein takes a different
folded shape than the normal protein.
◦ Diseases may develop because some normal prions
spontaneously change into the infectious form of the
protein and then alter the prions in other cells in a chain
reaction.

hPrions, can take on two different
conformations
 The prion on the right, in a helical conformation,dissolves easily in water and is relatively
benign.
 The prion on the left, in a beta-sheet conformation, tends to stick to other similar prions and
forms plaques.
 These plaques disrupt the structure of healthy tissue, resulting in the "spongy" texture found in
the brains of infected

Pathogenesis of vCJD
 Infected Beef eaten by humans
Not affected by cooking
 After the ingestion of prion it passes through the lymphoid
formations of the intestine (Peyer plaques) where it can be
replicated
 transported along nerve fibers at a rhythmus one millimeter
by day
 reaches the spinal cord and the brain
 In the brain stem prions accumulate and convert normal
prion proteins to the disease-causing form PrPSc.
 Years later, spongiform encephalopathy results when a
sufficient number of nerve cells have become damaged
 Causes the characteristic lesions

Histological Findings on Post
Mortem
 Bovine Spongiform Encephalopathy (BSE) is so named because of the spongy
appearance of the brain tissue of infected cattle (and also in the human beings)
when sections are examined under a microscope
 Variant CJD in humans: section of cerebral cortex stained to show
aggregates of PrPSc within plaques and more finely distributed
throughout the grey matter (Prion Proteins stains brown)

Histological Findings on Post
Mortem
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A characteristic feature of variant Creutzfeldt–Jakob disease is the presence of “florid plaques”
composed of a core of PrPSc amyloid surrounded by vacuoles { variant Creutzfeldt–Jakob disease is
distinguished by the abundance of PrP amyloid plaques, which are often surrounded by a halo of
intense vacuolation.

Neurologycal symptoms of vCJD
Initial neurogycal symptoms
 severe depression
 intense feelings of despair
 withdrawal from your family, friends and the world around you
 anxiety
 irritability
 difficulties sleeping
Advanced neurological symptoms:
 loss of physical co-ordination, which can affect a wide range of functions, such as walking,
speaking and balance (ataxia)
 muscle twitches and spasms (myoclonus)
 loss of bladder control and bowel control
 blindness
 swallowing difficulties (dysphasia)
 loss of speech
 loss of voluntary movement (akinesia)

Advanced psychological symptoms
 loss of memory, which is often severe
 problems concentrating
 confusion
 feeling agitated
 aggressive behaviour
 loss of appetite,
 paranoia, which is when you feel that people are
secretly out to harm you
 unusual and inappropriate emotional responses,
such as laughing when you hear bad news or
bursting into tears for no apparent reason

Final stages
 The disease usually runs its course in about
seven months, although a few people may live
up to one or two years after diagnosis.
 Totally unaware of their surroundings and need
of totally care.
 Lost of the ability to speak.
 Death usually in one of two ways:
◦ due to infection –pneumonia
◦ due to respiratory failure

Affected regions of the brain
 Being a neurodegenerative desease multiple regions of the brain are affeected
 Frontal Lobe: creative thought, problem solving, intellect, judgment, behavior, attention, abstract
thinking, physical reactions, muscle movements, coordinated movements, smell and personality.
 Parietal Lobe: Visual functions, language, reading, internal stimuli, tactile sensation and sensory
comprehension will be monitored here.
 Motor Cortex- monitor and control movement throughout the body.
 Temporal Lobe: The temporal lobe controls visual and auditory memories. It includes areas that help
manage some speech and hearing capabilities, behavioral elements, and language. It is located in the
cerebral hemisphere.
 Occipital Lobe: The optical lobe is located in the cerebral hemisphere in the back of the head. It helps
to control vision.
 Cerebellum balance, posture and coordination, allowing humans to move properly and maintain their
structure.
 Amygdala: to emotions, memories and fear.
 Hippocampus: memory, specifically converting temporary memories patial relationships, for accurate
movements
 Hypothalamus: mood, thirst, hunger and temperature.
 cerebral peduncle which allows voluntary motor function to take place.
 Pons: sensory analysis or motor control sleep.
 Medulla: vital body functions such as the heart rate and breathing.

 Medically known as Bovine Spongiform
Encephalopathy (BSE), this ailment affects the
central nervous system (CNS) of cattle. Mad
cow disease belongs to a group of
Transmissible Spongiform Encephalopathies
(TSE).This is a group of neurodegenerative
disorders that affect animals and humans
Read more at
Buzzle: http://www.buzzle.com/articles/mad-
cow-disease-symptoms.html

DIAGNOSIS
 only in advanced stages of the disease can
brain abnormalities be detected by MRI
(magnetic resonance imaging). vCJD is
fatal, usually within 13 months of the
onset of symptoms.

DIFERENTIAL DIAGNOSIS
vCJD must be differenciated from:
 Alzheimer
 Huntington

Treatments
 No effective treatment exists for
Creutzfeldt-Jakob disease or any of its
variants
 palleative care alleviating pain and other
symptoms

Prevention
 Prions are incredibly resistant to heat, chemicals,
and even radiation.
 The United States Department of Agriculturee
and the Food and Drug Administration (USDA &
FDA) take a number of measures in three areas
to counter the Mad Cow threat:
1. Restrictions on the import of cattle and cattle
products from the U.K. and other countries with
BSE or at risk of BSE;
2. Testing cattle brains for BSE; and
3. A rule intended to prevent the feeding of cattle,
sheep or goats parts to cattle.

My personal experience analizing
events around me.
 In this course, learning about the neurobiology of
each day in my life has allowed be to better
realize how I exist. Now I begin to understand
the complex interaction between me, my being
and the out world.This course made me realize
the little, the small an apparently insignificance of
neurons and their relation to the universe of
being alive and living experiences. More than an
academic course it has been to me a personal
experience with myself.
 As I m learning or trying to memorise events I
imagine how the information is moving around
the regions of my brain involved

Consulteed bibliogrphy
 http://www.ninds.nih.gov/disorders/cjd/detail_cjd.htm
 http://www.millerandlevine.com/news/bse/
 http://www.mayoclinic.org/diseases-conditions/creutzfeldt-jakob-
disease/basics/treatment/con-20028005
 http://www.nhs.uk/Conditions/Creutzfeldt-Jakob-disease/Pages/Symptoms.aspx
 http://zl.elsevier.es/es/revista/radiologia-119/enfermedad-creutzfeldt-jakob-
hallazgos-resonancia-magnetica-13142171-originales-2009
 Johnson RT. Prion diseases. Lancet Neurol. 2005;4:635-642.
 Creutzfeldt-Jakob diseaseDifferential diagnosis Raymond P Roos
MDhttp://www.medmerits.com/index.php/article/creutzfeldt_jakob_disease/P8
 http://www.buzzle.com/articles/mad-cow-disease-symptoms.html
 http://www.nhs.uk/Conditions/Creutzfeldt-Jakob-disease/Pages/Symptoms.aspx