What is Mad Cow Disease?
Mad Cow Disease is the common name for Bovine Spongiform Encephalopathy (BSE).
BSE was first recognised in the UK in 1986.
It is a chronic, degenerative disorder affecting the central nervous system of cattle. It is caused by rogue proteins, known as prions, that reproduce within the brain of the infected cow. As the disease progresses, the brain starts to look like a sponge, hence the term "spongiform".
BSE belongs to a group of progressive, degenerative neurological diseases known as Transmissible Spongiform Encephalopathies (or TSEs). This group also includes scrapie. Scrapie affects sheep and goats and has similar symptoms to BSE.
Currently, there is no cure for BSE.
Why is BSE such a serious problem?
BSE is a significant threat to human health. There is very strong evidence that consuming meat or meat products from an animal infected with BSE can cause variant Creutzfeldt-Jakob Disease (or vCJD) in humans. There is currently no cure for vCJD and it is a fatal disease.
A confirmed case of BSE in Australia could severely affect export and domestic markets for Australian beef and beef products. In turn, this could have a major effect on jobs and businesses in the beef industry and its various support industries. It could also have a significant effect on our tourism and hospitality industries.
BSE is a disease that spreads relatively slowly if not controlled. However, both BSE and its human equivalent, vCJD, have exceptionally long incubation periods. When a human is diagnosed with vCJD, he or she may have caught it from eating infected beef up to twenty years earlier. This extended incubation period makes tracing the source of infection much more difficult.
Which animals does it affect?
Cattle are the only food animal species known to be affected by BSE. It is thought that sheep and goats may be susceptible to BSE through eating contaminated food. However, BSE has not been diagnosed in these species.
Sheep and goats are susceptible to a similar disease known as scrapie. Other types of transmissible spongiform encephalopathies are known to affect different animal species.
What are the signs?
BSE usually affects cattle over two years old. Most cases develop symptoms gradually over a period of several weeks or even months. Some animals can deteriorate very rapidly. Only a small proportion of affected cattle show what would be considered typical "mad cow" signs. Most suspects show several (but not all) of the following symptoms if they are observed closely enough:
apprehension and nervous disposition
excessive sensitivity to stimuli (light, noise, touch)
manic kicking when milked
occasional aggression directed at other cattle or humans
swaying gait, sometimes with high stepping of the feet, particularly the hind legs
difficulties in walking or getting up
loss of condition, weight or milk yield
Some symptoms may be subtle in the early stages but can usually be recognised by experienced stockmen and vets.
Does it affect humans?
There is strong evidence that BSE can cause variant Creutzfeldt-Jakob Disease (vCJD). This human condition is a fatal brain disease. Evidence suggests that vCJD is caused by people eating BSE-infected beef or beef product. Milk and milk products are not thought to be carriers of the BSE agent.
Current evidence suggests that vCJD is not spread from person to person.
From October 1996 through to October 2017, a total of 175 human cases of vCJD were reported in the United Kingdom. Outside the UK, 53 cases were confirmed.
One of the major concerns about vCJD is the long incubation period. Current thinking is that it may be 20 years or even longer.
Currently, there is no cure for vCJD.
If we were to have a case of vCJD, would that mean BSE had arrived in Australia?
Not necessarily.
Australia has tough quarantine regulations to keep BSE out and vCJD has a potentially long incubation period. Someone diagnosed with vCJD is more likely to have contracted the disease from infected meat eaten overseas.
How could BSE be introduced into Tasmania?
BSE could be introduced through the importation of:
- BSE infected cattle
- BSE infected meat
- BSE infected livestock feed.
What is Australia doing to prevent BSE?
Australia maintains its BSE free status through:
A complete ban on importing live cattle from all countries that have reported cases of BSE
A compulsory ban on the feeding of feedstuffs containing meat and bone meal to ruminants. This ban is backed up by tight regulations on the labelling of feedstuffs.
As a further measure, Animal Health Australia has an ongoing national BSE surveillance program. Under this program, hundreds of brains are tested each year from cattle and sheep that display certain nervous symptoms. This is to prove to world markets that Australia remains BSE and scrapie free.
How do cattle get BSE?
It is widely believed that the UK outbreak was spread from cow to cow by feeding meat meal. This practice is banned in Australia.
The cause of the UK epidemic has not been proven. The most popular theory is that it was caused by the feeding of scrapie-infected meat-and-bone meal to cattle, and that the outbreak was amplified by feeding rendered bovine meat-and-bone meal to young calves.
There is currently no evidence that BSE can spread from cow to cow. Contaminated feed is the most likely cause of any spread of the disease.
What would happen if we had an outbreak of BSE in Australia?
Based on current knowledge and previous outbreaks overseas, any outbreak is likely to affect only a few properties and may be limited to just one property.
If a case of BSE was confirmed, the infected property would be placed under quarantine. Any other properties deemed to be "at risk" of having an animal with BSE would also be quarantined. Strict biosecurity measures would be used to ensure that potentially infected meat could not enter the human food chain. Tracing would be undertaken to find the source of the disease and to identify any other herds that may be "at risk".
Cattle exhibiting the symptoms of BSE would be slaughtered and their brains sent to a laboratory for examination. Any cattle not showing symptoms (but considered to be "at risk") would be tested many times over an extended period.
Monitoring for symptoms of BSE would be significantly increased for all Tasmanian herds.
Since BSE is not considered contagious, widespread restrictions on livestock movements are unlikely. Any movement restrictions would probably apply only to infected or suspect properties. Restrictions on people moving around the Tasmania are also unlikely.
How would an outbreak affect the community?
As BSE is a significant risk to human health, even a single case would cause some community concern.
A significant drop in the demand for Australian beef, from export markets and within Australia, would be expected. This is likely to cause job losses in the livestock industry and its various support industries. It may also trigger some job losses in the tourism and hospitality industries.
Where is BSE?
BSE was first diagnosed in 1986 in the United Kingdom. Almost all known cases of BSE have been in the UK - of more than 188,000 cases worldwide over the last 22 years, more than 183,000 have been in the UK. The UK epidemic peaked in early 1993, when almost 1,000 new cases a week were confirmed. There were 3 new cases reported in the UK in 2013.
Since the start of the UK epidemic, around 5,000 cases of BSE have been diagnosed in other countries:
Significant numbers of cases have been recorded in Ireland, Portugal, France, Switzerland, Germany, Spain, Italy and Belgium.
Several other European countries have recorded very small numbers of BSE cases.
The only countries outside Europe that have reported more than one or two BSE cases have been Japan (36 cases), Canada (21 cases) and the USA (3 cases).
Australia has never had a case of BSE.
Advice to livestock owners
If you own cattle, sheep, goats or deer you must understand and comply with the Australian Ruminant Feed Ban.
This ban prohibits ruminants being fed all meals, including meat and bone meal (MBM), derived from all vertebrates, including fish and birds.
Contact Biosecurity Tasmania (details below) if you become aware of anyone selling livestock feed that is not properly labelled. This includes 'backyard' processors.
Talk to your vet about the national surveillance program for BSE and scrapie, Bucks for Brains. Compensation ($330 for cattle and $110 for sheep) may be paid to farmers for veterinary-assisted testing of an eligible animal. This is an important part of the ongoing effort to demonstrate to world markets that Australia is BSE and scrapie-free.
More information