As the re-wilders - or whatever they're calling themselves this week - gush about beavers and badgers, bison and wild boar, or even lynx, bears and other extinct - or not so extinct - furry critters, we ponder over the news grabbing headlines for livestock farmers.
Vaccination for zoonotic tuberculosis? That'll do it.
We've explored this path many times before, not least in our last posting. So why do our primary Farming Union, our new Chief Veterinary Officer, veterinary organisations and even some farmers support yet another money wasting effort to repeat the errors of the past?
As the Zuckerman report pointed out in 1980, four long decades ago, vaccinating cattle on a wide scale in the 40s and 50s did not work. See below:
105. BCG vaccination of cattle has been tried in several countries, including the UK and France, but it has been found neither practical nor effective.
In this country MAFF conducted two vaccination trials during the 1940s and 1950s, the results of which have not been widely published. The first trial ran for eleven years and involved four herds of cattle which were known to have naturally-occurring bovine TB. Forty-seven tuberculin-test-negative calves were vaccinated at six-monthly intervals with BCG made from the bovine tubercle bacillus. At the end of the trial period 25 per cent of the vaccinated animals, and 50 per cent of their 'contacts', were found to have tuberculous lesions.
106. The second trial involved considerably more cattle, but did not last as long as the first, owing to the start of the area-eradication programme. Some 5,000 cattle in 73 herds were involved, and at the end of the trial, post-mortem examinations revealed that 30 per cent of the vaccinated animals, and 50 per cent of the non-vaccinated, had TB lesions.And bang up to date, the OIE (Office des Internationale Epizootics) has similar reservations, with the vaccination of cattle advised to be limited to countries where test / slaughter are either not affordable or socially acceptable (P.22 in the above OIE document) :
Bovine tuberculosis is an intractable problem where ‘test-and-cull’ policies are not affordable or socially acceptable, or where Mycobacterium bovis infection is sustained by wildlife reservoirs.More trials are planned in third world countries, as described in this paper.
Our newly minted CVO, Dr. Christine Middlemass is also on the crusade, waxing lyrical in Farmers Guardian about a new tool in the box.
No. BCG vaccination is a very old tool. And from the 1940s onwards, when used on cattle, it hasn't worked. So now a development of a DIVA test is to be trialled, to identify the 'reactor' cattle that actually are not reactors at all. We are not a third world country.Yet. But for our beleaguered cattle farmers, it may feel like that.
Vaccination is not a panacea - for any disease. And in the case of our cattle, when exposure to wildlife residues of bacteria are so 'challenging' ( that means high. ) it is unlikely to have much effect.
Immunity relies on either a natural response or an 'acquired' response to exposure. Acquired response is by vaccination, but immunity is very dependent on what epidemiologits call 'dose response'. In other words, if a single dose is very high, or the candidate is exposed to multiple small doses, the challenge is too great and disease is the result.
The excretions from TB infected cattle have been found to be miniscule - and of course, if a reaction is seen to the TB test, they are shot. Whereas infected badgers contaminate our grassland, water courses and everything they come into contact with and which our cattle share. Even their milliary lesions ( microscopically tiny) are hooching with cfus - colony forming units - of bacteria.
For the level of that infectivety, see answers to our Parliamentary Questions.
And after ruminating on those 300,000 cfu's in 1ml of urine, squittered across grazing land in 30ml incontinent dribbles, we asked how many cfus did it take to infect a cow? The answer was just 70 cfu
Vaccination is not a panacea - for any disease. And in the case of our cattle, when exposure to wildlife residues of bacteria are so 'challenging' ( that means high. ) it is unlikely to have much effect.
Immunity relies on either a natural response or an 'acquired' response to exposure. Acquired response is by vaccination, but immunity is very dependent on what epidemiologits call 'dose response'. In other words, if a single dose is very high, or the candidate is exposed to multiple small doses, the challenge is too great and disease is the result.
The excretions from TB infected cattle have been found to be miniscule - and of course, if a reaction is seen to the TB test, they are shot. Whereas infected badgers contaminate our grassland, water courses and everything they come into contact with and which our cattle share. Even their milliary lesions ( microscopically tiny) are hooching with cfus - colony forming units - of bacteria.
For the level of that infectivety, see answers to our Parliamentary Questions.
And after ruminating on those 300,000 cfu's in 1ml of urine, squittered across grazing land in 30ml incontinent dribbles, we asked how many cfus did it take to infect a cow? The answer was just 70 cfu
We are fast approaching the situation in this country, where our once proud cattle industry is relegated to the status of the third world. Unable to trade: unable to export.
Dr. Middlemass ended her FG piece with this paragraph:
"Vaccination is potentially an effective tool to reduce infection in cattle, but ultimately we do not want to have the pathogen out there which can infect cattle.”
And that last sentence is probably the only bit worth mentioning in this whole sorry affair.
From stockyard of the world, to our livestock industry's graveyard - in three generations.
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