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 includes scrapie, which affects sheep and goats and has symptoms similar to BSE.
Currently, there is no cure for BSE.
Why is it such a serious problem?
BSE is a significant threat to human health. There is very strong evidence that consumption of meat or meat product from a BSE infected animal can cause a similar disease in humans, known as variant Creutzfeldt-Jakob Disease or vCJD. There is currently no cure for vCJD and it is a fatal disease.
Because of this significant threat to human health, an outbreak of BSE in Australia could seriously affect both our export and domestic markets for 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.
Unlike Foot and Mouth Disease, which spreads very quickly if not controlled, BSE spreads relatively slowly. The problem, however, is that both BSE and its human equivalent, vCJD, have an extraordinarily long incubation period. This means that, for example, where a human is diagnosed with vCJD, he or she may have caught it from eating infected beef up to twenty years earlier. This makes tracing of the disease source much more difficult.
Which animals does it affect?
Cattle. It is thought that sheep and goats may be susceptible to BSE through eating contaminated food. However, cattle remain the only known food animal species with disease caused by the BSE agent.
Sheep and goats are susceptible to a similar disease known as scrapie.
What are the signs?
Typically, BSE affects cattle over two years old. Most cases show a gradual development of symptoms over a period of several weeks or even months, although some 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 the human condition known as variant Creutzfeldt-Jakob Disease (vCJD), which is a fatal brain disease. The 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.
It is thought 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, and 53 cases were confirmed outside the UK.
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. Because of the potentially long incubation period of vCJD and because Australia has tough quarantine regulations to keep BSE out of the country, if a person were to be diagnosed with vCJD, it is more likely that he or she would have developed the condition from infected meat product eaten while overseas.
How could BSE be introduced into Tasmania?
BSE could be introduced through the importation of infected cattle, infected meat or infected feedstuff.
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.
We also have 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
that tests hundreds of cattle and sheep brains from animals that display certain nervous symptoms each year. This is to demonstrate to world markets that Australia remains BSE and scrapie free.
How do cattle get BSE?
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 little doubt however that the UK outbreak was spread from cow to cow by feeding meatmeal. This practice is banned in Australia.
Current thinking is that BSE is not contagious. The most likely cause of any spread of the disease would be the feeding of contaminated feedstuff.
What would happen if we had an outbreak of BSE in Australia?
Because of the nature of BSE, it is likely that any outbreak would affect a small number of properties and possibly even just one property.
The first action would be to place the infected property under quarantine, together with any other properties deemed to be "at risk" of having an animal with BSE. Strict biosecurity measures would be put into effect on these properties to ensure that potentially infected meat did not enter the human food chain. Then, tracing would be undertaken to find the source of the disease and also to identify any other herds that may be "at risk".
Animals exhibiting the symptoms of BSE would be slaughtered and their brains sent to a laboratory for examination. Any animals that do not show the symptoms, but that were still deemed to be "at risk" would be tested many times over an extended period.
There would also be a significantly increased level of monitoring of all herds in Tasmania.
Because BSE is not considered to be a contagious disease, it is unlikely that there would be significant restrictions on the movement of livestock, other than those that might be applied to the infected or suspect properties. There would probably be no restriction on people moving around the State.
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. This concern would be likely to translate into a significant reduction in the demand for Australian beef, both in our export markets and within Australia. That would result in job losses in the livestock industry and its various support industries. It is likely that there would also be some job losses in the tourism and hospitality industries.
Where is BSE?
It 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 twenty two years, more than183,000 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
Make sure you fully understand the restrictions on feeding prohibited pig feed and restricted animal materials
as they apply to ruminant animals.
If you become aware of anybody selling feedstuff that is not properly labelled, including any 'backyard' processors, report them for investigation to the Program Coordinator (Animal Welfare, Biosecurity and Product Integrity)
at NRE Tas on tel. 03 6165 3777.
Participate in the national surveillance program for BSE and scrapie. Compensation ($300 + GST for cattle and $100 + GST for sheep) may be paid to farmers who report an animal with some of the above symptoms and agree to have the animal tested by a vet. This is an important part of the ongoing effort to demonstrate to world markets that Australia is BSE and scrapie-free.
For more information on the national TSE surveillance program: