Bovine spongiform encephalopathy (BSE), commonly known as mad cow disease, is a fatal neurodegenerative disease (encephalopathy) in cattle that causes a spongy degeneration in the brain and spinal cord. BSE has a long incubation period, about 30 months to 8 years, usually affecting adult cattle at a peak age onset of four to five years, all breeds being equally susceptible. In the United Kingdom, the country worst affected, more than 180,000 cattle have been infected and 4.4 million slaughtered during the eradication program.
The disease can be easily transmitted to humans by contamination of food with the brain, spinal cord or digective tract of infected organs. However, the infective agent is present in almost all bodily tissues of infected animals (blood included), which is why transmission is so likely through consumption of meat products.
The disease was spread as a result of cattle (normally herbivores) being fed on the remains of other bovines that were infected (e.g. in meat and bone meal). The accumulation of misfolded proteins (BSE prions) in the brain occured, causing symptoms and eventual death.The epidemic was probably accelerated by the recycling of infected bovine tissues prior to the recognition of BSE. The origin of the disease itself remains unknown. The infectious agent is distinctive for the high temperatures at which it remains viable.
The first confirmed animal to fall ill with the disease occurred in 1986 in the United Kingdom, and lab tests the following year indicated the presence of BSE; by November 1987, the British Ministry of Agriculture accepted it had a new disease on its hands.Subsequently, 165 people (until October 2009) acquired and died of a disease with similar neurological symptoms subsequently called (new) variant Creutzfeldt-Jakob disease.
Symptoms in cattle:
-Change in attitude/behaviour
-Inability to coordinate simple movements e.g. standing and walking
-Weight loss but not appetite loss
-Limited milk production
Tuesday 30 October 2012
Schmallenberg Virus
In November 2011 a new virus was identified which had been causing problems in Germany and the Netherlands since August. This was named ‘Schmallenberg virus’ (SBV) after the German town where the virus was first identified.
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. At the begining of 2012 there were suspected cases in thr South and East parts of England. Deformed lamb were tested and the viral infection was confirmed to be the cause. Further cases occured in Southern and Central England later.
As yet, the disease has remained soley European with outbreaks in: Germany, Belgium, England, the Netherlands, Denmark, Spain and Italy. So far the disease has only affected goats, sheep and cattle. The disease is highly unlikely to be zoonotic (affecting humans), as so far no human cases have been detected and the viral strains clostest to the SBV all only affect animals.
Transmission
It is suspected that the disease is transmitted by biting insect vectors, such as midges and mosquitos but the exact mechanism of transmission is still unknown due to the recent nature of outbreaks. It is likely that initial introduction of the virus to the UK resulted from wind-blown insect vectors originating in Europe.
Symptoms
-In adult animals: diarrhoea, fever, a reduction in milk yield, with a full and rapid recovery over several days. The infection tends to remain with the herd for 3-2 weeks.
-In Newborns and Foetuses: The 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.
Diagnosis/ Post mortem techniques
Histopathological: Microscopic examination of tissues in order to study disease manifestations.
Serological: The study of blood serum and other bodily fluids in order to test for disease.
Virological: The study of the infecting virus.
- Carcasses of abnormal lamb/calves should be sent to the VLA with a blood clot from the dam; this allows an indirect test for antibodies to be conducted.
Treatment
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.
Recent News:
A ram in Orkney recently tested positive for SBV after being moved there. The virus is reportedly moving North across britain,and it is vital that farmers maintain good biosecurity to prevent this relatively problematic virus from spreading further. Having isolated the virus, vaccinations are currently being developed in order to trigger the body to produce virus neautralizing antibodies, and the aim is to have a vaccine by the end of 2012.
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. At the begining of 2012 there were suspected cases in thr South and East parts of England. Deformed lamb were tested and the viral infection was confirmed to be the cause. Further cases occured in Southern and Central England later.
As yet, the disease has remained soley European with outbreaks in: Germany, Belgium, England, the Netherlands, Denmark, Spain and Italy. So far the disease has only affected goats, sheep and cattle. The disease is highly unlikely to be zoonotic (affecting humans), as so far no human cases have been detected and the viral strains clostest to the SBV all only affect animals.
Transmission
It is suspected that the disease is transmitted by biting insect vectors, such as midges and mosquitos but the exact mechanism of transmission is still unknown due to the recent nature of outbreaks. It is likely that initial introduction of the virus to the UK resulted from wind-blown insect vectors originating in Europe.
Symptoms
-In adult animals: diarrhoea, fever, a reduction in milk yield, with a full and rapid recovery over several days. The infection tends to remain with the herd for 3-2 weeks.
-In Newborns and Foetuses: The 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.
Diagnosis/ Post mortem techniques
Histopathological: Microscopic examination of tissues in order to study disease manifestations.
Serological: The study of blood serum and other bodily fluids in order to test for disease.
Virological: The study of the infecting virus.
- Carcasses of abnormal lamb/calves should be sent to the VLA with a blood clot from the dam; this allows an indirect test for antibodies to be conducted.
Treatment
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.
Recent News:
A ram in Orkney recently tested positive for SBV after being moved there. The virus is reportedly moving North across britain,and it is vital that farmers maintain good biosecurity to prevent this relatively problematic virus from spreading further. Having isolated the virus, vaccinations are currently being developed in order to trigger the body to produce virus neautralizing antibodies, and the aim is to have a vaccine by the end of 2012.
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