The effects of the various different strains of TSE
are all fairly similar, causing gradual dementia in the sufferer.
This is due to the Prions that are
found in TSE sufferer's brains gradually
build up into plaques. These deposits
then have a negative effect on the surrounding tissue causing
neural links to degenerate and nerve cells to die off, generally
in the cerebrum and cerebellum areas of the brain. This gives
the brain of the infected person the characteristic spongy appearance
(hence Spongiform in the name), which is clearly visible in postmortem.
These signs can only be seen after death, but the degeneration
of the brain matter does have very obvious effects to the living
sufferer. The incubation periods vary due to a number of different
factors (species of sufferer, strain
of TSE, initial dose, length of exposure
etc.) but the first outward symptom is loss of muscle control.
This causes a very slight shaking at first, but the situation
can degenerate as the Ataxia worsens
the sufferer gradually becomes more and more restricted in the
range of voluntary movements that they can make. It is not too
long after this point that the neuropathology
becomes too severe for the brain to function and the TSE
sufferer dies.
The other effect of brain degeneration is purely psychological,
because of the destruction of neural pathways impulses travelling
from the sensory organs, particularly eyes and ears, can become
confused with other signals, and this jumbling up causes hallucinations
to occur, becoming more real and more frightening as the disease
progresses. Although these symptoms are only definitely known
from sufferers accounts to occur in the human strains of TSEs,
it is logical to presume that the occur in the other animal strains
of TSEs as well as the diseases are
all so similar in every other way.
