flowchart LR
reactor["Infectious cow ('Reactor')"]
s["Susceptible cow"]
reactor --air--> s
reactor --water--> s
I managed to find an interesting programme on BBC iPlayer last night (not always easy): Brian May: The Badgers, the Farmers and me. Though it contains distressing scenes, I found it much more hopeful than I was expecting.
Around fifteen or more years ago, Anne Brunner, a conservationist, appeared on Brian May’s property with a hedgehog, asking whether this and other rescued wild animals could be released on his property. This led, for May, to an interest in local ecology and animal welfare, and through this to particular concerns for the plight of tbe badger in England & Wales.
Existing Transmission Model
In England & Wales, more so in the south than the north, Bovine TB affects cattle, and through this the livelihood of farmers who raise livestock. Farmers are both mandated to conduct a skin test on their cows every 60 days and - if the test is positive for a cow - to declare the cow a ‘reactor’ and (let’s not use euphamism) kill the animal.
A long held belief amongst farmers and government agricultural scientists was that Bovine TB, like TB in people, is primarily a respiratory infection, and transmitted primarily through air and water.
However, even once all cows that test positive for TB using the standard skin test are killed, bovine TB still, sadly, often seems to recur in farms previous afflicted. This led to the assumption that another vector of infection was responsible, wild badgers, who get close to cows, share water and air with them, and so are presumed to infect them
flowchart LR
cw[Cows]
reactor["Infectious cow ('Reactor')"]
r2["newly infectious cow (hidden reactor)"]
sc["Susceptible cow"]
ib["Infectious badger"]
st{"Skin test"}
cw --> st
kl>killed]
st --positive-->reactor --> kl
ib --infects--> sc
st --negative-->sc
sc --becomes--> r2
r2 --> cw
Badger Culling
Based on this transmission, it follows that culling (killing) only infectious cows isn’t enough to stop herds becoming infected. Badgers also have to be culled (killed). And because testing is expensive, and the farmers don’t own or profit from the badgers, the approach taken was to assume all badgers were potentially infected and infectious, and cull (kill) any found near farms ‘just in case’.
This mass culling (killing) of badgers was something that struck May as immensely inhumane and unfair, a presumption of guilt and imposition of a death sentence on an entire class of animal. In May’s words:
As a species that inhabited Britain long before humans, and who have an equal right to be here, they are now being brutally persecuted, for a crime - I believe - they didn’t commit.
First Response: Activism
Over a decade ago, May’s response was to petition vocally for the rights of badgers to exist, and for the government to change their policy regarding the culling of badgers. This brought him allies and attentions, but also set him in opposition to government, and to farmers, who both believed in the model of transmission outlined above. This approach engorged hearts that were already bleeding, but ultimately did little to change policy, and so the extent of badger culling in England & Wales.
Second Response: Scientific Research
So, May changed tack. He sought to find flaws in the above disease transmission model, to become - in effect - an epidemiologist, and as part of this to work with farmers.
May’s hope was that a new disease transmission model could be demonstrated, one in which badgers do not constitute a predominant vector of transmission. Of course, hope is just that, and May is clear in stating that - even if he wrong about this - he would still oppose the mass culling of badgers on ethical grounds.
Approach
So, what did May do? He worked with a farmer, and a vet. The vet devised an enhanced test, actually a composite of three tests: the skin test currently used, and two other - more expensive (and intrusive) - tests. The suspicion was that the skin test alone was not, from a diagnostic perspective, the Gold Standard it was assumed to be: some cows who test positive may not be infected or infectious (a false positive), and some cows who test negative may be infected or infectious (a false negative). By using enhanced testing, May sought to get closer the true Gold Standard we might hope for (especially when a positive test is a death sentence for a cow), rather than the Fool’s Gold Standard May, and the vet, were starting to suspect the Skin Test was in reality.
And why does this matter? Because if there are false negatives in a tested herd, then there are hidden reactors, i.e. cows within the stock that, despite testing negative, are still infectious to other cows. This would mean that an apparently ‘clean’ herd, in which all apparently infectious cows have been removed, actually still contained some infectious animals, who could then infect the rest of the herd.
The difference in implication is massive: if the Skin Test were a true Gold Standard then any new infections in cows would have to be due to an exogenous cause (hence, badgers). If instead the Skin Test were a Fool’s Gold Standard, then the cause of new apparent infection could be endogenous: the cows were infecting the other cows, and no exogenous infection from badgers was needed to be assumed.
By performing more enhanced testing of the cows, a much higher proportion of the infectious cows (‘reactors’) were identified, and so there were far fewer reactors left in the herd to infect other cows. Sadly this of course meant more cows were killed as a result of this test in the short term, but - if the endogenous infection hypothesis were true - would mean far fewer would be killed prematurely in the longer term.
Using PCR tests, May and the vet were also able to successfully test for the pathogen responsible for Bovine TB, M Bovis, in various candidate transmission vectors. In particular, they were able to identify that cow faeces contains much higher levels of M Bovis than previously thought, and so that faeces was a much more potent transmission vector than previously assumed.
By first enhancing the tests for Bovine TB at the test farm, and then by increasing the standards of hygiene for the herd - in particular greatly reducing the scope for faecal transmission - May, the vet, and the farmer were able to stop transmission at the test farm within a decade.
A slightly unfortunate natural experiment may have also helped their case: they were unable to acquire permission to vaccinate the local wild badger population, meaning - when tested - they still carried Bovine TB. So, even though a potentially infectious pool of M Bovis still existed in the local wild badger population, the test farm itself still did not become infected.
Changed Model
In short, they had developed fairly strong evidence against the following transmission model:
flowchart LR badger --air--> cow badger --water--> cow
And for the following transimission model:
flowchart LR cow --faeces--> cow cow --faeces--> trough trough --water--> cow
Gentleman Ecoscientism
The epilogue of the documentary suggests that, by collecting the above evidence, running the above tests, engaging with farmers - especially skeptical and previously hostile farmers - May was successfully able to change the minds of those whose minds needed to be changed to prevent further mass cullings. This research took around a decade to produce, and by the sounds of it came at some substantial cost to May, both financially, and reputationally amongst those ‘hearts’ who had previously supported him as an activist, but were wary of his efforts to engage with those farmers that - some activists at least - saw as ‘the enemy’.
By the sounds of it, May’s efforts as scientist may now finally turn out to be successful, not despite but because, though motivated by heart, they spoke to mind. At the age of 77, May may now finally be successful in preventing the killing of hundreds of thousands of wild animals unnecessarily, and stopping the potential extinction of badgers in large swathes of England & Wales.
But of course May was only able to engage in such a long-standing effort because of three things: his passion, his scientific acumen, and his wealth.
So, in this sense, May’s research seems almost like a return to the Gentleman Scientists of the Victorian and previous eras, a kind of atavistic return to the inequitable, but sometimes productive, roots of scientific research more generally, in which independently wealthy eccentrics devoted decades of their otherwise unstructured lives to pursuing personal interests and obsessions, with the birth of scientific journals themselves emerging as collections of correspondence between similarly minded Gentlemen Scientists, collated by elite institutions (like the Royal Society) where such (mostly) Gentlemen could meet, fraternise, and share their passions and interests with similarly minded (and well-heeled) folk.
I don’t know quite what to make of this from a broader socioeconomic perspective… but at least, thanks to May, the badgers’ future in England & Wales is now a bit more secure!