Page 9 - Livestock Matters - Spring 2013

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Schmallenberg virus
- what
you and your vet can do
The Schmallenberg virus (SBV) was only discovered in
Germany in 2011 and reached England early in 2012.
Schmallenberg virus is spread by midges
Iain Richards
XLVets Director
Charlie Lambert
Lambert, Leonard & May Veterinary Group
Lamb born alive and quickly dispatched
with relatively mild signs - flexed front
left and deformities to back feet. Its twin
was unaffected.
Lambs born with all four legs flexed
and twisted.
This lamb had to be delivered by
caesarian and was born alive. Note the
overlong back legs.
There are still a lot of unknowns about the
disease. However, what is known is that SBV
is spread by midges. When an animal is
bitten by an SBV-infected midge, it will
be viraemic for about six days before the
animal's immune system overcomes it.
Unfortunately, it is not known how long this
immunity lasts.
The typical signs of infection by the
Schmallenberg virus in dairy herds are milk
drop, diarrhoea and an increased number of
returns to service. When cows meet the virus
during early pregnancy, foetal deformities can
result, creating difficult calvings and requiring
Caesarean operations to be performed.
Where ewes have encountered the virus in
early pregnancy the consequences can be
equally dramatic, with dead or deformed
lambs being born.
XLVets survey
XLVets has carried out a national survey
into the prevalence of the SBV, utilising the
bulk milk test through Biobest Laboratories
in Edinburgh.
XLVets Director Iain Richards explains the
findings: ‘The Schmallenberg virus is not a
notifiable disease so there are no official
national measures of its spread. However,
with 50 independent vet practices from
Orkney to Penzance, with 25% of the UK
dairy cow population under their care,
XLVets has been well-placed as an
organisation to gain a good overview of
the national situation.
‘Last October and November we carried
out a survey amongst the XLVets practices to
investigate what proportion of herds had
been exposed.
‘The virus is spread by midges which have
come into the UK from the Continent. So not
surprisingly, the survey revealed an almost
100% prevalence in herds tested in the
southern parts of England. The results from
farms in the North of England were more
patchy, with a greater incidence of herds
testing negative to the virus. This probably
reflected local weather patterns with wind
carrying midges to some, but not all farms.