schmallenberg presentation
TRANSCRIPT
School of Veterinary Medicine and Science
Schmallenberg virus in Europe
Tarlinton, R., Daly, J., Dunham, S., Kydd, J.
School of Veterinary Medicine and Science
Schmallenberg why the fuss?
• Discovered in cattle with diarrhoea in Germany and the Netherlands in autumn 2011
• Genetically very similar to a group of viruses (Akabane virus) known to cause birth defects in calves and lambs in Australia and Japan
• Mostly affects ruminants (sheep, goats and cattle in particular)
• Tests and monitoring therefore developed• More than 6,000 farms in Northern Europe reported
deformed lambs or calves in spring/summer 2012 • http://www.youtube.com/watch?
v=jtZ7kDTQWMM&feature=player_embedded#!
School of Veterinary Medicine and Science
How the virus works• Generally causes mild or no
disease in adult animals (diarrhoea in cattle)
• If a pregnant animal is infected the virus replicates in the nerve cells of the foetus
• This (depending on when the animal is infected) leads to:– abortion– abnormalities of the bones
and joints due to failure of normal muscle development
– neurological deficits due to failure of brain development
Photos courtesy of Amanda Straughton and Jennifer Price
School of Veterinary Medicine and Science
How does Akabane behave in Australia and Japan?
• It is spread by biting midges• In endemic areas most
animals are infected pre-puberty and are immune
• Only sporadic abortions/deformities are seen
• If weather conditions change the range of the vector may extend, resulting in large numbers of naive animals being infected
• This leads to large-scale outbreaks of foetal deformities
Photo: culicoides.net
School of Veterinary Medicine and Science
What we know now• The virus has been found in
Culicoides midges and this is probably how it is spreading in Europe
• Unfortunately these midges are found all over Europe
• Most cattle and sheep in the area where the virus was first identified have had it. It is assumed they are immune and won’t have another affected calf or lamb
• It is spreading throughout the UK and other parts of northern Europe that didn’t have it last year at the moment Map courtesy of Flu
trackers.com October 2012
School of Veterinary Medicine and Science
The UK as of Jan 2013• The virus definitely circulated in the UK in summer/autumn
2012• 976 holdings across most of England and Wales have been
exposed to the virus (AHVLA Dec 2012)• Also first cases in Northern Ireland• Vets who have been sending bulk milk samples from dairy
herds to BioBest laboratories to test for antibodies are reporting almost all herds have been exposed
• Anecdotal reports of large numbers of ewes scanning empty
• Data from our own indoor herd would indicate we have a lower percentage of animals exposed (25%) compared with the 70-100% reported in Belgium and the Netherlands
School of Veterinary Medicine and Science
The likely impact• There are likely to be deformed lambs and calves
born in spring/summer 2013• Numbers will vary from farm to farm as the
deformities will depend on what stage of pregnancy the animals were at when infected
• Data our students collected last year demonstrate losses may be as high as 30% on some severely affected holdings
• The virus will most likely circulate in further years (we have the midges)