From: ProMED-mail <promed@promedmail.org>
Source: Eurosurveillance Weekly archives, Volume 7/Issue 34, 21 Aug
2003 [edited]


Transmissible Spongiform Encephalopathies in sheep and goats
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The European Commission has issued a series of answers to a selection
of questions on Transmissible Spongiform Encephalopathies (TSE), the
family of illnesses that includes Creutzfeldt Jakob Disease (CJD) in
humans, Bovine Spongiform Encephalopathy (BSE) in cattle, and scrapie
in sheep and goats.

The document states that scrapie is not considered to be
transmissible to humans or to pose a risk to man on the basis of the
available data. European Union (EU) legislation to prevent the spread
and transmission of BSE, however, does apply also to sheep and goats
as a precautionary measure (for example, removal of specific risk
material like brain and spinal cord since 2000, and ban on feeding
mammalian meat and bone meal (MBM) to ruminants since 1994).

The principal transmission route of BSE is thought to be MBM derived
from infected animals. BSE has never been found in sheep living in
fields. During the 1980s and early 1990s, sheep in the United Kingdom
and elsewhere were partially fed with feedstuffs containing the same
type of contaminated MBM that was responsible for causing the spread
of BSE in cattle. This has caused scientists to question whether BSE
might also have infected the population of small ruminants. The
feeding of MBM to ruminants has been forbidden in the EU since 1994
(1), and a total ban on feeding MBM to farmed animals has been in
place since January 2001 (2).

It has also been known for some time that a BSE-like disease can be
experimentally transmitted to sheep by feeding them material derived
from the brains of BSE-affected cows. This artificially produced
disease in research trials cannot be distinguished from scrapie by
examination of clinical symptoms or by rapid tests on the brains. It
can only be distinguished with certainty by the use of a mouse
bioassay, a testing technique that may take up to 2 years to
complete. The limited number of mouse bioassays that have been done
on natural scrapie cases so far have failed to yield a BSE-like
strain, and to date there is no evidence of the existence of BSE in
the sheep and goat population under natural conditions. New evidence
is constantly being reviewed by the EU scientific committees.

The most recent opinions of the Scientific Steering Committee (SSC)
on BSE in small ruminants were adopted in April 2002 and, updating
previous opinions of October 2001, February 2001, & September 1998.

The opinion reaffirms the SSC's view that there is no evidence that
BSE is present in small ruminants under field conditions. It issues a
range of recommendations in terms of specified risk material, use of
rapid tests, individual identification, breeding for resistance,
flock certification, and culling measures. It also describes how a
combination of approaches might be used to protect public health in
the event of BSE being confirmed in small ruminants under field
conditions.

More information on TSE and BSE is available from the Food Safety
section of the European Commission website.

References:
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1. Commission decision of 29 Jan 1999 amending for the second time
Decision 94/381/EC concerning certain protection measures with regard
to bovine spongiform encephalopathy and the feeding of mammalian
derived protein (notified under document number C(1999) 198) (Text
with EEA relevance) (1999/129/EC). Official Journal of the European
Communities 1999; L 41/14:16.2.1999.

2. Commission decision of 27 Dec 2000 prohibiting the use of certain
animal by-products in animal feed (notified under document number
C(2000) 4143) (Text with EEA relevance) (2001/25/EC). Official
Journal of the European Communities 2001; L 6/16: 11.1.2001.