Schmallenberg virus · Schmallenberg virus Information for farmers and vets in Great Britain...
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© Crown copyright 2012 AG0004-0312-v2 March 2012 Schmallenberg virus Information for farmers and vets in Great Britain Geographical distribution The disease is widely distributed throughout Germany, the Netherlands, Belgium, and northern and Central France and has now been detected in England, Italy and Luxembourg. Species affected Currently we know the virus will infect and cause disease in sheep, cattle and goats. We would also recommend that keepers of exotic or wild ruminants, such as the camelid and cervid family (alpacas, llamas and deer) are vigilant. 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. Research work suggests that live infected animals have the virus in their blood stream for two to five days, when biting insects may acquire the virus which they can then transmit to another susceptible animal during blood- feeding. 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. It is likely that initial introduction of the virus to the UK resulted from wind-blown insect vectors. Ruminants in the south, south west and east of England, and imported ruminants and their offspring, are currently at the highest risk of showing signs of the disease; at this time this would be manifest, particularly as birth of offspring with deformities or neurological signs. Other regions including the midlands and south Wales were at medium risk of midge incursion during the summer and autumn 2011, and therefore farmers in these areas are also requested to be vigilant for Schmallenberg virus associated problems in their livestock. As the virus can localise in the tissues of foetuses, it is uncertain as to whether there is potential for live actively infectious lambs, calves and goat kids in the spring, which could continue the spread of the infection next year. Cont... 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 December 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 November 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. Page 1 of 3
Transcript of Schmallenberg virus · Schmallenberg virus Information for farmers and vets in Great Britain...
© Crown copyright 2012 AG0004-0312-v2March 2012
Schmallenberg virusInformation for farmers and vets in Great Britain
Geographical distributionThe disease is widely distributed throughout Germany, the Netherlands, Belgium, and northern and Central France and has now been detected in England, Italy and Luxembourg.
Species affectedCurrently we know the virus will infect and cause disease in sheep, cattle and goats. We would also recommend that keepers of exotic or wild ruminants, such as the camelid and cervid family (alpacas, llamas and deer) are vigilant.
TransmissionOrthobunyaviruses 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.
Research work suggests that live infected animals have the virus in their blood stream for two to five days, when biting insects may acquire the virus which they can then
transmit to another susceptible animal during blood-feeding.
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.
It is likely that initial introduction of the virus to the UK resulted from wind-blown insect vectors.
Ruminants in the south, south west and east of England, and imported ruminants and their offspring, are currently at the highest risk of showing signs of the disease; at this time this would be manifest, particularly as birth of offspring with deformities or neurological signs. Other regions including the midlands and south Wales were at medium risk of midge incursion during the summer and autumn 2011, and therefore farmers in these areas are also requested to be vigilant for Schmallenberg virus associated problems in their livestock.
As the virus can localise in the tissues of foetuses, it is uncertain as to whether there is potential for live actively infectious lambs, calves and goat kids in the spring, which could continue the spread of the infection next year.
Cont...
BackgroundBetween 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 December 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 November 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.
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© Crown copyright 2012 AG0004-0312-v2March 2012
Clinical signs and post mortem findingsTwo clinical presentations have been observed due to Schmallenberg virus infection.
Adult animalsIn adult cows the acute infection 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, although there is anecdotal evidence of milk drop in milking sheep in Netherlands.
Newborn animals and fetusesThe second presentation of the disease is associated with abnormalities in animals born alive or dead at term or aborted following infection of the dam, affecting mainly sheep but also cattle and goats. Malformations observed to date include bent limbs and fixed joints (arthrogryposis), twisted neck or spine, a domed appearance to the skull, short lower jaw and brain deformities (spaces filled with fluid in cerebral hemispheres, abnormally small parts such as cerebellum and brainstem) 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.
DiagnosisWhilst this is not a notifiable disease, please contact your veterinary surgeon if you encounter cases of ruminant neonates or foetuses which are stillborn, show malformations or are showing nervous disease and you suspect Schmallenberg virus infection. Veterinary surgeons should then contact their AHVLA/SAC laboratory if they suspect infection with the virus. Details of premises with suspected or confirmed disease are treated as confidential and will not be made publicly known.
Suspect cases will be sampled for histopathological and virological examinations as appropriate. Confirmation of infection is by detection of virus sequences using real time PCR on tissues. There is currently no serological (blood) test available but work is in progress to develop one.
In England and Wales examinations for Orthobunyavirus will be free of charge but AHVLA will require a full history to provide the necessary clinical and epidemiological information. Any other diagnostic tests requested will be
charged the normal surveillance price. In Scotland the usual, subsidised fees for post mortem examinations will apply and a comprehensive examination will be carried out. The cost of examinations for Orthobunyavirus will be included in the price.
If cases occur outside laboratory working hours, please keep carcasses chilled until they can be submitted for testing.
Treatment and controlThere 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.
Malformations affecting lambs exposed to the virus in pregnancy may lead to lambing difficulties. Excessive force must not be used during lambing as this may risk injury to both the ewe and lamb. Farmers should contact
Affected lamb born with fixed flexed forelimbs and abnormal over-long fixed hindlimbs
Lamb born dead with arthrogryposis, showing a twisted spine and abnormally flexed deformed legs
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© Crown copyright 2012 AG0004-0312-v2March 2012
Animal Health and Veterinary Laboratories Agency is an executive agency of the Department for Environment, Food and Rural Affairs and also works on behalf of the Scottish Government, Welsh Government/Llywodraeth Cynulliad Cymru and the Food Standards Agency. www.defra.gov.uk/ahvla
Further informationInformation on the current disease situation in Great Britain is published on the AHVLA website at: http://www.defra.gov.uk/ahvla/news
More detailed information on the international disease situation will be published on the Defra website at: http://www.defra.gov.uk/animal-diseases/monitoring/
Please contact your local AHVLA Laboratory (England and Wales) or SAC Disease Surveillance Centre (Scotland) if you need further guidance:http://www.defra.gov.uk/vla/vla/vla_contacts.htm#laboratories
http://www.sac.ac.uk/consulting/services/s-z/veterinary/contact/dsc/
their veterinary surgeon in these cases which cannot be delivered naturally.
When a ewe requires assistance with lambing it is important that strict hygiene measures are carried out.
Embryotomy (dissection and removal of a foetus that cannot be delivered naturally) should only be carried out on dead foetuses by operators competent to carry out the procedure. It should never be used to remove a live animal.
AHVLA regional laboratories are reporting severe abnormalities in some live born lambs. They are visibly distressed and unlikely to survive or thrive long term. You should consider as soon as possible, and in liaison with your private veterinary surgeon as required, if any offspring deformities are likely to result in any immediate or long term welfare problems during rearing. Euthanasia may be required in severely affected lambs and additional support and care may be required during the rearing period for less severely affected lambs. You should also consider whether any abnormalities will affect the animals’ intended future use and fitness for transport in the long term.
Risk to humansAt the moment, a Europe-wide risk assessment has concluded that Schmallenberg virus is unlikely to cause illness in people. As yet, no human cases have been detected in any country, and the most closely related viruses only cause animal disease. However, as this is a new virus, work is ongoing to identify whether it could cause any health problems in humans. Please see the Health Protection Agency website for more information at http://www.hpa.org.uk/
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.
Information for visitors to farmsVisitors to farms are advised to adopt the usual hygiene precautions for farm visits, such as washing of hands after touching animals and particularly before eating. Pregnant women are potentially at risk of acquiring a range of infectious diseases from animals, and should follow existing Defra guidance that advises them to avoid close contact with animals (including sheep, cows and goats) that are giving birth. This includes:
•avoiding contact with newborn or aborted lambs, calves or kids;
•avoiding handling clothing or boots that may have come into contact with these animals;
•ensuring that partners take appropriate hygiene precautions.
Further information can be found on the following websites:Health Protection Agencyhttp://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/EmergingInfections/SchmallenbergVirus/Defra advice to pregnant women to avoid close contact with animals that are giving birth http://www.defra.gov.uk/news/2012/01/20/advice-to-pregnant-women-to-avoid-close-contact-with-animals-that-are-giving-birth/Health & Safety Executive Information Sheet 23: Preventing or controlling ill health from animal contact at visitor attractionshttp://www.hse.gov.uk/pubns/ais23.pdf Defrahttp://www.defra.gov.uk/animal-diseases/a-z/schmallenberg-virus/
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