Tests done at the Institute for Animal Health’s Pirbright Laboratory during Saturday morning (22 September) have confirmed that a cow in Suffolk had been exposed to bluetongue virus, cause of the disease bluetongue. The animal had been exhibiting symptoms consistent with that disease, although diagnosis could not be made on symptoms alone as these are also common to other diseases. Tests and expertise that have been developed for many years at IAH Pirbright are being brought to bear on the outbreak, the first record of bluetongue virus in the UK.
The UK farming community has been bracing itself for a bluetongue outbreak ever since bluetongue came to northern Europe for the first time in 2006, diagnosed by IAH. Research at IAH had shown that conditions in the UK would be suitable for the establishment and spread of bluetongue.
A veterinarian of Animal Health (formerly the State Veterinary Service), who had observed the symptoms, spoke on Friday with Dr Chris Oura, Head of the Bluetongue Reference Laboratory at the Institute for Animal Health (IAH). Subsequently a blood sample was sent to IAH where it was received during the night. IAH scientists set up tests, looking both for antibodies against bluetongue virus, and for the genetic material (RNA) of the virus (using the polymerase chain reaction test, PCR). The results, reported to Defra, were positive for both tests. Working through Saturday night, IAH scientists then set up further PCR tests to identify the particular type of bluetongue virus that was in Suffolk. At 03.00 on Sunday morning Defra was informed that the virus was of serotype 8, the same as the one causing disease in Belgium and neighbouring continental counries.
More samples from animals on the farm and neighbouring premises will be received by IAH Pirbright Laboratory during late Saturday night, for immediate testing. As stated on the Defra web site this is not a confirmed outbreak unless further investigation demonstrates that disease is circulating i.e. is not confined to the one animal so far in which the virus has been detected.
Bluetongue disease in sheep is characterised by a fever that may last for several days. The virus mainly affects the cells lining small blood vessels causing them to leak, and this can lead to reddening and swelling of the lops, mouth, nasal linings and eyelids. Nasal discharge, excess salivation and frothing are common. Animals lose condition rapidly, which leads to muscle degeneration and lameness. Animals may also die from the disease. Bluetongue usually causes fewer symptoms in cattle.
There are 24 types (serotypes) of bluetongue virus. The serotype of the virus that caused the outbreaks in Belgium, France, Germany, Luxembourg and the Netherlands last year, and which re-emerged this year was identified by IAH as being serotype 8. This serotype had never been anywhere in Europe previously. IAH determined the genetic fingerprint of this serotype 8 virus, demonstrating that it had probably originated in sub-Saharan Africa (see map). Tests are in progress through the night at IAH to see if the Suffolk virus is serotype 8.
Bluetongue virus is spread by biting midges of the genus Culicoides(for pictures click here and here). After they have bitten a target animal e.g. cow, sheep, goat, they suck the blood of the animal. If the blood contains bluetongue virus then the virus grows in the midge, which then spreads the virus to other animals at a later feed. The disease is spread further when the midges are carried on the wind. Easterly winds from neighbouring continental countries, such as Belgium, are recognised as being a threat to the eastern counties of England, as infected midges could be carried over the Channel . In April, John Gloster, of the Met Office, and who is seconded to IAH Pirbright, had estimated that if the disease did flare up again near coastal areas of Belgium, then south-east counties of England would be likely to be at risk between four and seven times per month from May to October, that being the frequency of easterly winds from the direction of Belgium. Bluetongue virus grows and spreads more efficiently during warm weather.
For more information on bluetongue in northern Europe visit see our information on bluetongue. These pages give updates on the 2006 and 2007 outbreaks of bluetongue in northern Europe, including a map of the outbreaks in northern Europe. Also available are pictures showing the symptoms (clinical signs) exhibited by sheep that are infected with bluetongue virus, and a brief description of the disease, the midges and the virus .
Contact numbers
To speak to our bluetongue experts, contact Dr Dave Cavanagh at the Institute for Animal Health’s
press office:
mobile (preferred) 07789 941568 (messages can be recorded);
office 01635 577241 (messages can be recorded: please repeat your telephone number twice);
dave.cavanagh@bbsrc.ac.uk