BSE, like many TSEs
is a relatively new disease and has only been officially recognised
for just over a decade. The first official case was acknowledged
in 1986 on a Surrey farm, although it is thought that up to 100
cattle developed the disease before this, and the Ministry for Agriculture Fisheries and Food
(MAFF) in the UK may have known about
the disease as long ago as 1983.
Scientists are not completely sure how BSE
was created, or how it spread so quickly from the initial outbreak,
but the strongest theory is that it was transmitted from scrapie
infected sheep meat in the cattle's food. This was possible because
the waste meat and skeleton that could not be used for human consumption
was ground up to produce meat and bone meal, a substance fed to
dairy cattle in order to increase their milk yields. It is thought
that through the practice of also using unwanted cow parts in
meat and bone meal some of the cattle who contracted BSE
from scrapie infected meal were
themselves rendered to meat and bone meal upon death, making lateral transmission
of the disease possible to huge numbers of other cows. The fact
that BSE has an incubation period
of two to five years means that many undiagnosed cattle were probably
being used for rendering, allowing huge amounts of BSE
agent to enter the food. One cubic centimetre of pure agent is
thought to be enough to kill up to ten million cattle, such is
the effectiveness of the Prion.
Even when a ban on bovine material being used in bovine food was
brought in in 1988 not all manufacturers of meat and bone meal
followed it strictly.
This produced a huge downward spiral as the number of infected
cattle rose alarmingly, spreading quickly across the UK, as many
as 800 cases a week were being reported at the outbreak's height!
This coupled with inactivity on the issue by the British government
led to a huge epidemic that may have disastrous repercussions
many years into the future.
