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Schmallenberg virus
Background
Between August and October 2011, outbreaks of disease in adult cattle that included mild to moderate fever, reduced milk yield, loss of appetite, loss of body condition and diarrhoea were reported in both the Netherlands and Germany. Testing for common causes proved negative.
From November 2011, abortion and stillbirths associated with foetal abnormalities, affecting mainly sheep but also cattle and goats, were identified in the Netherlands, Germany and Belgium.
A new virus was identified in December 2011 as the cause of both conditions. This was named ?Schmallenberg virus? after the German town where the virus was first identified.
In early 2012, the first cases were suspected in the south and east of England. In these initial cases, the disease was diagnosed following the testing of deformed lambs.
Schmallenberg virus is in the Simbu serogroup of the Orthobunyavirus group. This group of viruses includes many different viruses which occur in Asia, Africa and Australia, but have not previously been identified in Europe.
As this is a newly identified virus there are still aspects of the disease that remain unknown at this point until more research has been done.
Geographical distribution
The disease is widely distributed in the west of Germany, throughout the Netherlands, and in parts of Belgium and northern France and has been detected in England. See the summary of the latest situation in the UK.
Species affected
Currently we know the virus will infect and cause disease in sheep, cattle and goats.
Transmission
Orthobunyaviruses are typically primarily spread by biting insect vectors, such as midges and mosquitoes, although the routes of Schmallenberg virus transmission have not yet been confirmed. The potential for direct transmission (i.e. direct from one animal to another) is therefore, as yet, unknown.
If biting insect vectors are the major route of transmission, significant spread is believed unlikely during the winter period when biting insects are usually inactive.
It is believed Schmallenberg virus was circulating widely in sheep and cattle in the Netherlands and in a part of western Germany between August and October 2011. The initial introduction of the virus to the UK therefore may have resulted from either wind-blown insect vectors or via imported infected livestock during this period.
Clinical signs
In adult cows, cases of acute infection have resulted in diarrhoea, fever, a reduction in milk yield, with a full and rapid recovery over several days. Affected herds had outbreaks of disease lasting two to three weeks. In other species this stage of the disease has not been noted.
Clinical signs have not been reported in adult or growing sheep.
In newborn animals and fetuses, the disease has been presented as malformations
including bent limbs and fixed joints, brain deformities and marked damage to the spinal cord. Some animals are born with a normal outer appearance but have nervous signs such as a ?dummy? presentation or blindness, ataxia, recumbency, an inability to suck and sometimes fits. The foetal deformities vary depending on when infection occurred during pregnancy.
Risk to humans
There is unlikely to be a risk to human health from Schmallenberg virus; but this is not yet certain.
Farmers and veterinary surgeons are advised to take sensible hygiene precautions when working with livestock and abortion material. Although several members of the group of related viruses can affect humans, the ability to do so is thought to be due to a gene sequence which is not present in Schmallenberg virus.
Pregnant women should not have contact with sheep and goats at lambing/kidding time due to risks of exposure to other disease causing organisms.
Treatment and control
There is no treatment or vaccine currently available for this disease. As this is a new disease further work is needed to determine what control measures may be appropriate.
Diagnosis
This is not a notifiable disease, but farmers are asked to contact their veterinary surgeon if they encounter cases of ruminant neonates or fetuses which are stillborn, show malformations or are showing nervous disease. Veterinary surgeons should then contact their AHVLA/SAC laboratory if they suspect infection with the virus.
Suspect cases will be sampled for histopathological and virological examinations. Confirmation of infection is by detection of virus sequences using real time PCR on tissues. There is currently no blood test available but work is in progress to develop one.
DEFRA
Background
Between August and October 2011, outbreaks of disease in adult cattle that included mild to moderate fever, reduced milk yield, loss of appetite, loss of body condition and diarrhoea were reported in both the Netherlands and Germany. Testing for common causes proved negative.
From November 2011, abortion and stillbirths associated with foetal abnormalities, affecting mainly sheep but also cattle and goats, were identified in the Netherlands, Germany and Belgium.
A new virus was identified in December 2011 as the cause of both conditions. This was named ?Schmallenberg virus? after the German town where the virus was first identified.
In early 2012, the first cases were suspected in the south and east of England. In these initial cases, the disease was diagnosed following the testing of deformed lambs.
Schmallenberg virus is in the Simbu serogroup of the Orthobunyavirus group. This group of viruses includes many different viruses which occur in Asia, Africa and Australia, but have not previously been identified in Europe.
As this is a newly identified virus there are still aspects of the disease that remain unknown at this point until more research has been done.
Geographical distribution
The disease is widely distributed in the west of Germany, throughout the Netherlands, and in parts of Belgium and northern France and has been detected in England. See the summary of the latest situation in the UK.
Species affected
Currently we know the virus will infect and cause disease in sheep, cattle and goats.
Transmission
Orthobunyaviruses are typically primarily spread by biting insect vectors, such as midges and mosquitoes, although the routes of Schmallenberg virus transmission have not yet been confirmed. The potential for direct transmission (i.e. direct from one animal to another) is therefore, as yet, unknown.
If biting insect vectors are the major route of transmission, significant spread is believed unlikely during the winter period when biting insects are usually inactive.
It is believed Schmallenberg virus was circulating widely in sheep and cattle in the Netherlands and in a part of western Germany between August and October 2011. The initial introduction of the virus to the UK therefore may have resulted from either wind-blown insect vectors or via imported infected livestock during this period.
Clinical signs
In adult cows, cases of acute infection have resulted in diarrhoea, fever, a reduction in milk yield, with a full and rapid recovery over several days. Affected herds had outbreaks of disease lasting two to three weeks. In other species this stage of the disease has not been noted.
Clinical signs have not been reported in adult or growing sheep.
In newborn animals and fetuses, the disease has been presented as malformations
including bent limbs and fixed joints, brain deformities and marked damage to the spinal cord. Some animals are born with a normal outer appearance but have nervous signs such as a ?dummy? presentation or blindness, ataxia, recumbency, an inability to suck and sometimes fits. The foetal deformities vary depending on when infection occurred during pregnancy.
Risk to humans
There is unlikely to be a risk to human health from Schmallenberg virus; but this is not yet certain.
Farmers and veterinary surgeons are advised to take sensible hygiene precautions when working with livestock and abortion material. Although several members of the group of related viruses can affect humans, the ability to do so is thought to be due to a gene sequence which is not present in Schmallenberg virus.
Pregnant women should not have contact with sheep and goats at lambing/kidding time due to risks of exposure to other disease causing organisms.
Treatment and control
There is no treatment or vaccine currently available for this disease. As this is a new disease further work is needed to determine what control measures may be appropriate.
Diagnosis
This is not a notifiable disease, but farmers are asked to contact their veterinary surgeon if they encounter cases of ruminant neonates or fetuses which are stillborn, show malformations or are showing nervous disease. Veterinary surgeons should then contact their AHVLA/SAC laboratory if they suspect infection with the virus.
Suspect cases will be sampled for histopathological and virological examinations. Confirmation of infection is by detection of virus sequences using real time PCR on tissues. There is currently no blood test available but work is in progress to develop one.
DEFRA
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