Friday 12 August 2016

Badgers and TB, all wrong

Two days ago, I was telling a sorry story about my contribution to the killing of badgers Meles meles to protect small babies from contracting tuberculosis, a disease caused by the bacterium Mycobacterium tuberculosis: it's a argument that requires several 'logical' steps:

  • badgers bump into cows in the dark
  • transferring the bacteria as they touch noses
  • cow develops a case of TB between regular testing for the disease
  • bacilli infest the milk
  • and are not killed by pasteurisation
  • baby's innate immune system doesn't work quick enough
  • off to the consumption ward for invasive antibiotic treatment

Fast forward to last week when Dau.I sent me a link to an article in the Grauniad about badgers and cattle and tuberculosis. It's the kind of thing that the Guardian [city boys, Arts block educated] loves to publish: exposing boffins, farmers and the government as culpably inept, destructive and wasteful. We had a brief skype about it later and she asked with devastating rhetorical flourish "How could the badgers on our fields infect the cattle on the other side of the county borrrder if that boundary was defined by the Aughnabrisky River? Would they snuffle 600m down river to cross the 19thC hump-back road bridge?"

Now the Aughnabrisky isn't deep or wide except after a spill of rain across its mountainy catchment area. But if you-the-badger want only worms, insects and a bit of bonking in the Spring would you choose to get wet all over to achieve these desiderata?

But enough of me and my anecdotal [sample size N=1] badger and get down with some data from Cornwall. [R sample N=4 of super-cute badgers from Pinterest]. When I hung out with ecologists in the early 80s, a key piece of tech was the radio-collar. You couldn't hope to see what meadow voles Microtus pennsylvanicus were doing under the long grass but you could track their whereabouts by putting a teeny-tiny radio-transmitter round their necks and triangulating their position with a couple [or better, three] of receivers. Very crude, but sufficiently techy to smell like science if you were applying for grant money. The radio-collars didn't last very long: several of them seemed to finish up inside locally marauding cats Felis catus. Technology has moved on - bring on the GPS, lads! - and researchers from The Institute of Zoology in London have popped GPS tracking collars on 400 cattle and 100 badgers which shared the same space on 20 farms in Cornwall. In all more than 8,000 collar-nights were recorded for cattle and at no time did any cow come within coughing distance = 1.5m range of any badger. The fond imaginings of nose to nose contact in the dark between members of the two different species can now be dumped in the dustbin of fantasy.

One of the authors of the paper Prof Rosie Woodruffe asserts that culling badgers will "make no meaningful contribution to cattle TB control in Britain" despite costing millions. A key problem with TB is that test for carriers is far from being 100% accurate and reliable. The scientists suggest that the culling be stopped and the money devoted to more research for better immunological or DNA sequencing tests for the presence of M. tuberculosis. And who is going to develop these new tests? Scientists! One of the reasons for the continuation of culling is the investment - emotional, psychological, logistical - in culling. Thus pilot studies become full-blown programmes almost regardless of the results.

Back in my ecological days we used to refer to study animals as bigger than a breadbox [cows, badgers, easy] or smaller [voles, Mycobacterium tuberculosis, hard/invisible]. Current policy is to slaughter cattle if they are infested with TB and dispose of the carcasses in quicklime and by incineration. At the same time, the Mycobacterium-rich slurry from these cows [inhumanedoor model] and/or the fields where they have defecated [free-range] are classed as entirely fit for fertilising the grass which subsequent cattle will eat. I hadn't thought of that way of spreading tuberculosis: the bacteria can survive for many  Because they are small, the TB bacteria have been invisible in the equation.  It's easier to blame the black-and-white bread-boxes than blame the farming "industry" for self-destructive practices that have served to keep vets in their practice by government-mandated testing for a disease which is decisively encouraged by the way cattle are intensively raised and maintained inside.

A case could be made that the monstrous way we raise cattle in intensive systems have not only encouraged the spread of tuberculosis within that species but have also adversely affected the badgers as innocent bystanders who happen to hunt grubs on the same pasture. Eat more lentils: that will reduce the incidence of tuberculosis too.

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