Wednesday, September 24, 2008

'Bovine' Tuberculosis - 'Badger' Tuberculosis?

We have been castigated on this site many times for flagging up the many victims of 'bovine' TB. "It's 'bovine' the comments shriek, and "what bit of 'cow' don't you understand?" But this clever little bacterium is able to adapt to many mammals and work published by Brosch et al tells us that from the ancient tuberculosis line, the M.bovis lineage has firmly established itself in:
".... natural host spectra as diverse as humans in Africa, voles on the Orkney Isles(UK), seals in Argentina, goats in Spain, and badgers in the UK."
No mention of cattle there - even with a tag of 'bovine'. Not one. Which brings us full circle to why 'we' - that's 'we' as in cattle farmers - are testing and slaughtering cattle. It does not explain why the other half of that 'we', Defra, presently trawling the country gleaning support for its Cost and Responsibility Sharing Levy collection exercise, are hell bent on piling costs onto farmers while accepting no responsibility whatsoever for its own part in the eradication of this multi-species zoonotic disease - but let that pass.

Molecular geneticists say that analysis of recent work suggests that true cattle TB was eliminated by the 1970s, and what we have now is badger adapted TB spreading back into the environment. So maybe it's time for a name change. 'Bovine' TB becomes 'Badger' Tb. We like mycobacterium meles

The single most important thing - one may say the only thing of merit - that baby-Ben Bradshaw accomplished during his tenure of prevarication astride Defra's fence, was to make this disease, the so called 'bovine' TB, notifiable in all mammals. The result has been a steady increase in cases of companion animals and other grazing species as Defra picked up the tab for post mortems. And of course the inevitable spill over into human beings.

For twenty years since the low point of TB eradication in the mid 1980s, when less than 100 herds were under movement restrictions, and under 700 cattle slaughtered, successive administrations have ducked and dived, sanitised eradication policy - other than that applicable to cattle - and totally ignored the message those tested sentinels were giving. This culminated with a 'moratorium' introduced in 1997, on the control of badgers allowed under Section 10 of the Protection of Badgers Act, in response to confirmed outbreaks of cattle TB. Last year Defra proudly announced they had killed 28,000 cattle - but ignored their message. This year will be another vintage, with numbers up a staggering 42 per cent to May and some say, heading for 40,000 by the end of the year. But while Defra may be able to ignore this farm based carnage (except for moaning about its monetary cost, said to account for 40 per cent of Animal Health's budget) they will find it increasingly difficult to ignore the steadily increasing pile of 'other species' - the result of Bradshaw's notification amendment.

Figures seen by our editors confirm that while 'passive' surveillance (as Defra quaintly describe 'not actually looking for' a disease) of the past revealed a handful of cases in other animals between 1998 and 2004, from 2005 to 2007, incidence of 'bovine' tuberculosis rose sharply. In just those three years, spillover victims include 42 domestic cats, 24 llama, 19 domestic pigs, and single figures of goats, sheep, alpaca, ferrets and a dog. The areas where these animals were found are consistent with endemic TB in wildlife and sentinel cattle casualties. The largest group of casualties - the 42 cats - had identifiable spoligotypes described as
" various spoligotypes, each one consistent with the predominant strain at the location of the infected cat"


We have touched on this in previous postings, camelids here, and domestic cats here and here But the reason for all the testing and slaughter of cattle is not about the health and welfare of animals at all. The totally mislabelled 'bovine' Tuberculosis affects people. It is a zoonosis. It's what they do.

But the most recent case in humans, that of a Cornish lady, her dog and her child has finally alerted the main-stream media to the bigger picture of the total failure of the one sided, cattle based tuberculosis eradication programme operating in this country.

Describing the re-emergence of an old zoonotic threat, an unpublished paper submitted to the BMJ journal 'Thorax', warns that the high level of bovine TB infection circulating in cattle and wildlife across parts of the country is posing an ongoing health risk to humans.

Farmers Guardian has the story;
The paper discusses the case of a former veterinary nurse and her dog, from Cornwall, who contracted the same of the strain of the disease last year. It identifies badgers known to inhabit the woman’s garden as a possible source of infection.

The woman was diagnosed with bTB in late 2007, having felt unwell and suffered from a persistent cough for some time. Her daughter was also confirmed with latent bTB infection. Both were treated with a course of drugs.

The family’s pet dog began showing symptoms two months later. It was put down and subsequently confirmed with the same strain of M Bovis, the bacteria that causes bTB, as the woman.

The strain in question is a rare one found locally in cattle and badgers in the South West, prompting five scientists examining the case to suggest the infection therefore probably originated from either badgers or cattle. .


The point here we think, is that the spoligotype of the most misleadingly labelled mycobacterium bovis - 'bovine' TB, which has killed the dog, and infected its owner(s) is a strain known to circulate within tested (and slaughtered if they react to the test) cattle and untested but highly infective badgers in the SW of Cornwall. There is also doubt as to the assertion that the lady's previous employment as a 'veterinary nurse' and thus assumed intimate contact with cattle, was relevant.
"... they question whether the nurse could have been infected through contact with infected cattle while working as a veterinary nurse. However, this is considered unlikely as she had left the job three years prior to becoming infected and there was no sign of latent infection."
But the most telling phrase of FG's report we think is 'badgers known to inhabit her garden'. Inhabit, as in live. Not passing through then? And having examined the usual suspects, including the lady's past employment, this exposure would seem to be 'possible' (most likely) source of the outbreak.
Badgers were known to inhabit her garden and the scientists conclude that this was a more likely source of infection, according to veterinary sources who have seen the paper.

The Health Protection Agency said human cases of bTB did occur ‘occasionally’ in the UK but the current risk was considered ‘negligible’. But they also confirm that not all tuberculosis cases are strain typed. They were unable to provide the editors of this site with figures for the umbrella term 'tuberculosis complex' used to describe such 'untyped' cases. Farmers Guardian quote eight cases of m. bovis type tuberculosis in humans in the South West of England in 2006 and 2007 and 20 nationally in 2005. Only five cases in dogs have been identified in the past 20 years (to 2006).

In people under the age of 40 - 50, born outside the window of transmission opportunity presented by unpasteurised milk, prior to the TB eradication programme which finished in the mid 1960s, even a single victim is one too many. But as figures in our posting above show, and the horrendous, months long drug regime and other cases of onward transmission within human beings tell us, the spillover from environmental contamination with the misleadingly labelled ' bovine' tuberculosis is rising. And inevitably it will claim more victims than 40,000 cattle.

7 comments:

Anonymous said...

In view of the fate of the lady in Cornwall and her dog , should not our risk adverse Government be issuing guidelines to the public to avoid close contact with their cats and dogs where these pets can be in contact with the bTB bacterium.

Jim

Matthew said...

Probably they should Jim, but more likely they are weighing up countryside access and tourism against livestock farming. The increasing cases of TB in other mammals has snuck up rather more quickly than Defra probably expected.

Anonymous said...

This is worrying. We have badgers in and around our place, cattle in an adjoining field and a large garden where the dogs play. The impression I get is the Govt seem to be dodging the whole issue because of the animal lobby. Furthermore at the local scale I can't take any action on my own land to protect my dogs and family.

Matthew said...

Anon 6.08.

It is worrying. And it should be of concern to anyone with a grain of common sense.

The advice you would be given from the 'authorities' would be a softer version of what cattle farmers get, which is to minimise comntact opportunities.
In practise this is almost impossible on scale, cost and conflicting rights of access.

You may have better success with a large garden, remembering that VLA's badger pound has solid concrete walls sunk 15 feet down into the earth, to prevent them digging their way out.

If you have a sett on your property, then things are even more complicated: its residents having acquired far more 'rights' than either you, your children or your dogs.

Brian said...
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Matthew said...

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