The Bovine TB Problem

Bovine TB, or Mycobacterium bovis, or bovine tubercle bacillus, is part of the Mycobacterium tuberculosis complex. The organism is carried by many animals including deer, cats, dogs, pigs, alpacas, sheep and, of course, cattle. Mycobacterium bovis is an aerobic bacterium and the cause of TB in cattle. Bovine TB can jump the species barrier and cause tuberculosis in humans, and this is where the problem has historically been. In the 1930's and 40s, it was responsible for over 50,000 cases a year and 2500 deaths annually. By 1960, all herds had been tested twice for TB, and all animals which had tested positive, or 'reactors', were slaughtered and it became a notifiable disease.

The government introduced compulsory cattle testing and devised a compensation programme for all destroyed cattle. In the last decade, human contraction of Tb from animals has seen only handful of cases. 

 

Pasteurisation of milk, immunisation and a healthy diet have seen the number of cases reduce dramatically over the last 100 years and in most circles it is considered no longer a human concern. Farming practices have changed and food has become cheaper. Ironically, this intensive farming leads to poor condition for cattle, causing poor health, and could itself be contributing to the increase in bovine TB in herds. 

For the farmers, it is a different issue. Cattle with bovine TB cannot be moved and cannot be sold in Europe, causing great financial strain on farmers. [READ MORE] Whilst a vaccination for BCG is available for cattle, there is currently no approved test to differentiate between wild TB and vaccinated TB, although one has been researched. The Diva Test - READ HERE

It should be noted that cattle with bTB lesions do routinely and legitimately enter the food chain.

Save Me fully sympathises with farmers who are affected by this awful disease, but it does not believe, based on scientific evidence, that the solution lies in the culling of badgers. It believes that culling could make matters worse. 

The Krebs Review on Bovine TB in Cattle and Badgers reported in 1997 and concluded that, despite there being “compelling” evidence that badgers were involved in transmitting infection to cattle, the development of a control policy was made difficult because the effectiveness of badger culling could not be quantified with the data available. It therefore recommended that a large-scale field trial - the Randomised Badger Culling Trial (RBCT CLICK HERE ) - be set up to quantify the impact of culling badgers on incidence of TB in cattle, and to determine the effectiveness of strategies to reduce the risk of a TB cattle herd breakdown.

The Independent Scientific Group on cattle TB (ISG), which included several members of the Krebs Review group, was formed in 1998 to plan and subsequently provide independent oversight of the RBCT. It also provided advice on the content and direction of Defra's (then MAFF) TB research programme. The ISG published their final report on 18 June 2007. This trial slaughtered 9818. It stated that, "culling badgers would have no meaningful effect on bovine TB in cattle." You may have expected that to be the end of culling badgers, however...

On 19th July 2011, Caroline Spelman announced that the government would carry out two pilot badger culls in the areas shows below. This was part of the government's bovine TB eradication programme. 

Caroline Spelman's announcement of the proposed pilot badger cull.

WHAT DOES THIS MEAN?

Landowners who wish to cull badgers would need to apply for a licence from Natural England. 

The trials will assess the humaneness, efficacy and safety of the free shooting of badgers. 

Groups of qualified landowners under licence will be able to shoot badgers at night with a high-velocity rifle.

70% of the badgers in any trial area must be slaughtered.

Each trial area must be at least 150 km2

A cull can only spread the disease further, since it cannot be contained. The spread of the disease outside a cull zone is known as perturbation, which can only be prevented by hard boundaries and short culling periods. All lactating creatures in the wild – including rats and squirrels – carry bTB, and culling for a period exceeding five days will lead to an increase in the spread of the disease. Against scientific advice, the proposed culling period has been extended to six weeks, and, in the absence of hard boundaries, much of the wildlife would move in and out of the cull zones. Badgers, along with foxes and other wild animals, cross motorways every night (and most survive), so these cannot be regarded as a hard boundary. Badgers are also amazing swimmers, and can swim across large rivers and against the current. I’m sure you’re aware that 40% of farms in the hotspot areas have been TB-free for 10 years or more, and, naturally, they wish to stay that way.

Firstly, Lord Krebs’ statement, made in the House of Lords on 21 October, indicated that after 9 years the “very best” possible reduction we could expect would be a 16% decrease in TB.

Lord Krebs:

"My Lords, as has been said, bovine TB is a serious problem, and it deserves serious science to underpin policy. I do not want to take up too much time, but I hope that your Lordships will forgive me as an individual who has been involved in this over the past 15 years and, as has been said, instigated the randomised badger culling trial and took part in the review of the evidence with Sir Bob Watson last year. It is worth briefly repeating the facts: the long-term, large-scale culling of badgers is estimated to reduce the incidence of TB in cattle by 16% after nine years. In other words, 84% of the problem is still there. To reflect on what that means, this is not a reduction in absolute terms but actually a 16% reduction from the trend increase. So after nine years there is still more TB around than there was at the beginning; it is just that there is 16% less than there would have been without a cull. The number is not the 30% that the NFU quoted; that is misleading, a dishonest filleting of the data. The other thing that the experts conclude is that culling makes the situation worse at the beginning so it will take a long time to emerge into this Nirvana of a 16% reduction, and 84% of the problem is still there.

"That is just the background. I turn to questions that I hope the Minister will answer. Last Friday we were told by the Minister of State for Food and Farming that between 500 and 800 badgers would be culled in each of the two areas. The number, thanks to rapid badger reproduction over the weekend, is now 5,530 over the two areas-a fourfold increase. I am impressed. What this underlines is that if the policy is to cull at least 70% of the badgers, we have to know what the starting number is. This variation from just over 1,000 to more than 5,000 in the space of a few days underlines how difficult it is for us to have confidence that the Government will be able to instruct the farmers to cull 70% if they do not know the starting numbers. So my first question to the Minister is: how will he assure us that these numbers are accurate?"

SAVE ME is shocked the government would ignore all scientific advice and evidence and proceed with these pilot culls. We will campaign to prevent these pilot culls going ahead.

Below is a graph showing the amount of cattle slaughtered for various reasons - bTb is not the biggest issue. 

Information from The Cattle Book 2008 DEFRA:

Total cattle population on 1 June 2008 GB was 8,868,469.

Total number dairy cows (calved) over 2 years of age in GBm 2008, was 1,593,949. Total GB dairy cattle 3,133,006.

35.3% of cattle in GB 2008 were dairy cattle, 62.7% were beef, and 2% were dual-purpose and 'unknown' cattle.

Total number of milking dairy cows, over 2 years of age, estimated by the author to have been culled prematurely in GB, in 2008, was 301,096. This excludes the black column named Bovine TB. It has been added to the chart to represent the estimated 10,567 calved dairy cattle over 2 years of age, culled in connection with the TB control programme. It is acknowledged that dairy cows have over twice the incidence of bTB than beef cattle.

Total figure for cattle culled in connection with the bTB eradication programme in GB 2008 is 39,973

All figures in the chart, though carefully compiled, should be regarded as a close approximation and not exact. However they are useful for comparison purposes.

In the absense of Official Government Data on the premature culling of dairy cattle these above figures have been carefully extrapolated and compiled by the author from data gathered by the Kite Health and Culling Monitor of 2009 forr the year 2008. Their data covered 58,210 cows in 322 herds, with an overall culling rate for 2008 of 18.89%. Kite suggests a target benchmark of less than <25% replacement rate as a key performance indicator. Levels can vary from 12% to 45%. Note that the TB figures have dropped considerably in GB since 2008 due to ongoing cattle measures.

The excellent Kite scheme is an advisory/monitoring service for herdsmen. It is designed to help improve health, welfare and profitability of dairy cows. An aim of the scheme is to achieve a lower culling rate. Thus, the culling rate amongst non-participating farms is likely to be somewhat higher than figures given in the Chart (not the TB Column).

Some of the cattle slaughtered in connection with the bTB control programme go into the human food chain and the money obtained is used by Defra to offset some of the costs of the programme.

  1. http://www.apd.reading.ac.uk/AgEcon/livestockdisease/cattle/bovtuberculosis.htm
  2. http://www.defra.gov.uk/foodfarm/farmanimal/disease/atoz/tb/stats/documents/countyanimal/animl-2008.pdf
  3. The Kite's Health and culling Monitor gathered data from 2007 and 2008 and covers 58,210 cows in 322 herds (available online) The Heath and Culling Monitor was started in 2006.
    1. BTB poses negligible risk to human health in the UK. The current policy has a greater adverse effect on cattle welfare than the disease could
    2. The existing test and cull regime would take decades to achieve OTF status, if it ever did, whatever is done or not done to badgers
    3. The “skin test” is only suitable as a herd test. It misses far too many cattle (and condemns too many falsely) to be very effective in finding infected individuals and removing them from the herd
    4. It is widely said that countries which have achieved OTF status have addressed any wildlife reservoir. It is conveniently forgotten (by those wanting to slaughter wildlife) that the two examples they choose most often, Australia and USA, have used the skin test as a herd test – if one reactor is found the whole herd, however large, is slaughtered
    5. Most importantly cattle vaccination must be allowed. It could be used alone or alongside any other policies and methods. The vaccine and the accompanying test could be licensed this year with the political will
    6. Only EU law prevents cattle vaccination, and EU law over rules ours. Defra claim that it would take 5 years to change. They have been saying this for as long as anyone can remember and there is little evidence of efforts to actually change it. Other authorities say it could be changed very quickly. The French and Italians would probably just ignore it. It is intolerable that we cannot use vaccines to protect our cattle and the interests of our farmers against BTB. The reason for the EU prohibition, interference with the skin test, is no longer relevant as a different test would be used on vaccinated cattle. 

REFERENCES & PUBLISHED PAPERS

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