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Can we really ever expect to eradicate bovine TB?

 Added by  Sally
 15 Oct 2010, 6:01 PM

Can we really ever expect to eradicate a disease such as bovine TB which is still endemic in most of the world?
BBSRC are making £7M available for UK scientists to combat bovine tuberculosis (bTB).
The Biotechnology and Biological Sciences Research Counci (BBSRC) is supporting world-class research into the fundamental biology of bTB to address key basic bioscience gaps and will utilise advances in human TB research to provide insights into bTB, and vice versa (known as a 'one-health' approach). Up to £5M will be available for scientists to conduct high-quality fundamental research on bTB that focuses on basic underpinning bioscience in three themes; bTB vaccinology, the diversity of bTB strains, and interactions between the bTB pathogen and its hosts.
In addition and as part of the programme, Defra will provide up to £1M of research funding.
BBSRC will also make up to £2M available for scientists to develop non-animal models to accelerate bTB research, thereby reducing reliance on research animals. This part of the project will be collaboration with NC3Rs.
Professor Jackie Hunter, BBSRC Chief Executive, said: "We need to inject more basic bioscience research into the fight against bTB. BBSRC asked the community where the gaps in our knowledge were and it was clear from the responses that it is the fundamental understanding of the disease that needs to be improved. This funding will help explore the mechanisms whereby immunisation with vaccine induces immune protection in cattle, increase our understanding of the diversity of different bTB strains, and examine specific host-pathogen interactions."
Defra's Chief Scientific Advisor Ian Boyd said: "Fundamental research on bovine TB is essential in combatting all aspects of the bovine TB episystem. Therefore we are encouraged to see AHVLA, as the UK's leading bTB research laboratory, spearheading this new initiative with cutting edge academia to develop the next generation of tools to combat Bovine Tuberculosis."
Dr Vicky Robinson Chief Executive of the NC3Rs said: "We are pleased to be supporting the development of novel models that avoid the use of animals in research into bovine TB. Bovine TB is one of the biggest problems facing the cattle industry today, so the study of infection, virulence and host-pathogen interactions is highly important. This award will make it possible to reduce the reliance on animal models in this priority research area."
For more information, see: www.bbsrc.ac.uk/funding/opportunities/2014/eradbtb.aspx
Latest news is that bTB is getting into other areas of England via cattle movements. However, this should not be taken out of proportion as the vast majority of farms are still TB free (over 99%). 150 farms are now on additional testing regimes in South Lakeland and north Lancashire.
Lancashire/Cumbria border - DEFRA said five herds had tested positive for the disease over the last few months, including four in one area surrounded by the M6/A65. It is understood dozens of cows have already been slaughtered although no official figures are available.
The Animal Health and Veterinary Laboratories Agency (AHVLA) said contiguous testing was being carried out on surrounding farms in a bid to identify the source of infection, which is unknown.
A 3km enhanced surveillance testing area has been set up around Flookburgh on the Cartmel peninsula, Cumbria
The current fear is that bovine TB found in local cattle herds could spread into wildlife. In addition to badgers it states in one report that 'Deer, foxes, rats, hares and moles are all capable of carrying bovine TB'.
Info from: http://www.thewestmorlandgazette.co.uk/news/10407141.TB_hits_cattle_in_South_Lakes_and_north_Lancashire/?ref=twtrec
There is currently concern regarding the ear tag frauds (news reports April 2011) whereby farmers have been found to have cheated disease controls by swapping tags between healthy and infected cows. Criminal investigations are ongoing in the South West and Midlands after an investigation by trading standards officers in Gloucestershire. Some farmers are suspected of keeping productive dairy cows who test positive for the disease and sending less productive animals to slaughter. Farmers are compensated for their loss. The Department for Environment, Food and Rural Affairs (Defra) has apparently said that the fraud could be widespread and would undermine the case for a badger cull. In future in England DNA samples will be taken from cattle that test positive.
Mick G comments in email dated 7/4/11 If these farmers are prepared to keep Btb positive cattle in herd it shows they don't think Btb is a problem.
If powers that be are correct about bTB I was quite horrified when I watched BBC Countryfile on Sunday 27th Feb 2011. This programme included a bit about this issue and filmed the presenter's, (Adam Henson, a farmer) TB test.
When the vet came to check the last animal, a belted galloway that had been kept in isolation because she had been classed as inconclusive, they brought her out of isolation in a stock trailer, into the race, into the crush where she was then checked. She was then face to face with animals that had already been checked! All this was done in front of a vet (vets are supposed to be teaching farmers about biosecurity!) who then said that she tested positive! It was an open and complete disregard for all biosecurity measures that we are told were already in place, the animal had been isolated, she was already suspect, yet they brought her into direct contact with cattle that had just been cleared. We are told that the aerosol route is the most likely cause of the spread of the disease!
When will more effort be taken to prevent pollution of streams by slurry! This too seems a regular problem in some areas. Slurry can contain the bacteria that cause bTB!

New Zealand was widely recognised as the world leader in TB management and WAG has made many references to its strategy in Gwlad. However, what has not been admitted is the growing opposition to the widespread use of poisons being used to kill possums but which are also affecting other species.
It has recently been reported that New Zealand taxpayers will pay $150 million in the five years to 2015 to fund the Government's share of killing possums and managing bovine tuberculosis. The taxpayers' contribution of $30m a year is on top of $45m a year from beef, dairy and deer farmers, and $6m from regional councils.
The funding would appear to be financing a revised National Pest Management Strategy, to eradicate the disease in possums and other wildlife from one quarter of New Zealand's vector risk areas. This was about 40 per cent of land area. The initial 1998 pest management strategy was aimed at the trade-oriented target of meeting international levels for 'official freedom' from TB - having only 0.2 per cent of deer and cattle herds infected in 2013 - a level which would prevent trade rivals using TB incidence as a basis for seeking non-tariff trade bans on NZ meat and milk exports. But in 2007 MPs were told that TB-infected possums, ferrets, and feral pigs and deer remained in nine million hectares of NZ - about a third of the country - and those animals would continue to infect farmed livestock until the disease was eradicated from wildlife.
In 2009, a plan was implemented over 40 years, proposing to eradicate TB from pest animals, starting with a 15-year stage to 2025: trial TB eradication from large selected areas of heavily-forested country through control operations over a five-year period involving annual ground control and four to five yearly aerial 1080 control operations.This would be followed by five years of intensive wildlife monitoring and herd testing to ensure the disease was eradicated. IT IS NOT KNOwN IF THIS WILL BE SUCCESSFUL as it goes on to say 'If large-scale eradication proved feasible, the AHB would progressively eliminate it from the rest of the country under a new pest management strategy from 2025, with nationwide eradication taking another 20 to 30 years'! If these projections are true, this is farcical and NZ should not be held up as a country whose example the UK should be following.
Main information from http://www.nzherald.co.nz/business/news/article.cfm?c_id=3&objectid=10692507
Emails between Ruth and Sally 11 and 12 November 2010.
Dear Ruth, I have just finished another reading of Thoen et al's book and it would seem that areas of world which are classified as TB free are only those countries where there is no wildlife reservoir and they completely depopulated herds with any positive reactors. Pretty stringent measures that are not adopted in UK - not that I would wish them to be but surely in UK we cannot expect to eradicate if we do not depopulate as the test is not accurate.
Dear Sally, we have managed to virtually eradicate TB in humans in Britain, the majority of the small number of current cases being in prople who have resided in highly endemic countries ie immigrants from Africa, India etc. The majority of British cases are in the homeless and alcoholics and there are cases, even small outbreaks, in organ recipients or AIDS patients or of course secondary cases from immigrants who are shedding.
If a human is shedding TB on the breathe and will not turn up every day for daily observed therapy, or has a multiply drug resistant MDR-TB form or extremely drug resistant XDR-TB form they are incarcerated in an isolation room until they are no longer infectious. One person died at St Mary's after attempts to rid him of his highly resistant organism were unsuccessful. Many XDR-TB and MDR-RB cases do die. Of course they are as humanely treated as possible, and every effort made with clever drug combinations and removal of infected lung to cure them of shedding so they can go out again.
Email from Paul T 15/10/10
Perhaps the greatest victory for veterinary medicine – and using ‘eradication’ in the correct context. But Rhinderpest is caused by a single virus, with no antigenic or genetic varients and ONLY infects cattle. So once they had an effective vaccine it was decided that eradication was possible (test and cull plus vaccination in endemic areas). It is one of perhaps only about 10 diseases that could be eradicated with presently available technology. Smallpox was the first, Rhinderpest is the second, Drunculiasis should not be far behind (a nasty parasitic disease of humans), and there is a global campaign against polio which is also on its way out. Another disease in animals/humans that could be eradicated (and was eliminated from the UK in the early part of the last century) is Taenia solium/cysticercosis – the pork tapeworm, which can also cause a nasty neurological condition in humans. It ONLY infects pigs and humans and could be eradicated if resources were made available (perhaps invest some of the global bTB budget into it!)
But bovine TB is unlikely ever to be eradiacted as it is NOT very host specific (i.e. infects cattle, badgers, possums, deer, llamas, african buffalo etc etc....) Even local elimination is close to impossible and the best the authorities can hope for is ‘bTB free status’ (which is not total elimination, but <0.5% of herds having breakdowns over a 5 year period).
Interestingly reports have just been released indicating that Rinderpest has just been eradicated. This is another disease of cattle. It causes respiratory and gut problems that lead to diarrhoea, dehydration and eventually death of livestock. More than 80% of cattle who contract the virus die from it. It is a viral disease (unlike bTB which is caused by bacteria. It is only the second viral disease in history to have been wiped out by humans (the other being smallpox some 30 years ago).
John Anderson, the head of the UN's Food and Agriculture Organisation, called the success "the biggest achievement of veterinary history". Rinderpest is the first animal virus to be contained and then eradicated in the wild. But it has taken thousands of years!
The rinderpest virus originated in Asia but spread worldwide as a result of cattle movement (imported livestock and invaders such as Gengis Khan, whose oxen apparently carried the disease to other countries). As the virus spread, it left vast numbers of dead livestock in its wake, and communities without meat and milk. The loss of the animals, which were used to plough the land, crippled farming and led to widepsread starvation. It was apparently the catastrophic impact of rinderpest led to the establishment of Britain's national veterinary service in 1865, which through surveillance, culls and import restrictions, eradicated the disease in the UK two years later.
A global eradication plan for rinderpest, backed by the UN and the World Organisation for Animal Health, was launched in 1994. Scientists at the Institute for Animal Health's (IAH) Pirbright laboratory in Surrey developed pregnancy-test like kits that were distributed in affected countries so that local officials could identify and kill infected livestock. Animals in areas surrounding outbreaks were vaccinated to protect them from the disease.
The eradication programme was feasible because rinderpest has remained as a single strain since it was identified, so all animals can be protected by the same vaccine. Most viruses evolve into a variety of strains, making them much harder to control. Stocks of the rinderpest virus will be kept in high-security laboratories, including the IAH's own facility.
The last known outbreak of rinderpest was reported in Kenya in 2001, though some disease was thought to have lingered on in Somalia. The last animal vaccinations were given in 2006 and targeted surveillance in 2009 failed to spot new cases of the disease. On the back of the success, the UN closed field operations to curtail the disease this year.
"There has never been such an important and devastating disease as rinderpest in livestock," said Michael Baron of the IAH. "We've known about it and its problems for a thousand years and we've got rid of it."
With bovine TB there are many more complications. We are nowhere near eradicating it and the process of eradication is now causing more suffering than the risks of the disease itself.

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