Infectivity of vaccinated badgers

Last week, UCD Centre for Veterinary Epidemiology and Risk Analysis, UCD School of Veterinary Medicine, University College Dublin, and the Quantitative Veterinary Epidemiology group, Wageningen Institute of Animal Sciences, Wageningen University & Research, Netherlands published a paper -[link] on the vaccination of badgers.

 Over four years, groups of badgers were jabbed with either BCG or a placebo and then tested for results. The paper describes:

In this manuscript, we present the results of a badger field trial conducted in Ireland and discuss how the novel trial design and analytical methods allowed the effects of vaccination on protection against infection and, more importantly, on transmission to be estimated.

Cutting through all the guff, we pick out the following paragraphs:

Over the study period, 55 new infections occurred in non-vaccinated (out of 239 = 23.0%) and 40 in vaccinated (out of 201 = 19.9%) badgers.

This is 'protection against infection'  part. So after vaccinating, a difference of  just 3 per cent? But then the modelers got to work, and "Statistical analysis showed that susceptibility to natural exposure with M. bovis was reduced in vaccinated compared to placebo treated badgers: vaccine efficacy for susceptibility, VES, was 59% (95% CI = 6.5%-82%)." But crucially:

However, a complete lack of effect from BCG vaccination on the infectivity of vaccinated badgers was observed, i.e. vaccine efficacy for infectiousness (VEI) was 0%.

Infectivity of badgers is the amount of detritus left behind for any other mammal to fall over. That's the 'transmission' bit. Especially important for our sentinel, tested cattle, and described in the paper as " extremely important in the case of vaccination in badgers, as the ultimate goal is to help in the control or eradication of M. bovis infection in cattle."

 Not just in Ireland either. Our lot have been playing with BCG (at 10x the rate for humans) for several years. We discussed their results here - [link] and veterinary professionals gave their view here - [link]
And we also remember poor old badger D313 - [link] who had his dose of BCG and developed zoonotic Tuberculosis in pretty much every organ, during the Lesellier trial. -[link]

So the paper's 'stand out' paragraph for us is this blinder:

A reduction in the total infectivity of vaccinated and subsequently infected badgers in the field had been anticipated based on the reduction in disease progression observed in vaccinated compared to non vaccinated badgers in experimental studies (Chambers et al., 2011).

However, no reduction of infectivity was found in our study. The lack of effect of BCG vaccination on infectivity in the general badger population is thus at odds with the hypothesis that vaccination, by reducing disease progression, reduces the infectivity of vaccinated and subsequently infected badgers.

From this study, we cannot determine whether a similar reduction in disease progression to that observed in experimental studies was found in the field as no post-mortem data were available. Nevertheless, if that reduction in disease progression does exist, we did not find a concurrent reduction in infectivity. The lack of effect of vaccination on infectivity has implications in terms of the effectiveness of BCG badger vaccination in Ireland (or how much reduction of transmission is achieved by vaccination).

Post mortem data was available to Lesellier, and those vaccinated badgers all had lesions and all were shedding. (Link above)

The Farmers Union of Wales understands only too well, how ineffective faffing about with vaccinating badgers is. In an an article - [link] published by the Institute for Welsh Affairs earlier this year, Dr. Nick Fenwick describes the result of four years of vaccinating:

So it comes as little surprise that the latest official report on the badger vaccination programme in north Pembrokeshire, which cost £3.7 million, concludes that “Consistent trends in indicators of bTB incidence have not yet been seen…”

Perhaps someone should tell The Badger Trust, Rosie Woodroffe,  Brian May, and even the Secretary of State - link] And also ask, with these results echoing those of Lessellier in 2011, why on earth anyone is still promoting and funding this?  

Starstruck?

Would you choose a veterinary professional to tune your guitar? Probably not.

But today our Secretary of State for Agriculture tweeted about his meeting with superannuated star gazer, Dr. Brian May - he of Save Me fame - to discuss a way forward on the thorny question (at least for an upwardly mobile politician) of zoonotic Tuberculosis.

This was the Tweet from Save Me, updating Gove on the way forward. Improved cattle testing, vaccination and stupid farmers. Nice one.

Now Gove is not the sharpest knife in the box, having (according to Private Eye) attempted to unblock his lavatory with a vacuum cleaner - until he was stopped. We understand that he is however well known for echoing the thoughts of those to whom he spoke most recently.

So perhaps some refreshing factoids better make their way into his shell like.

 For instance, in our PQs over a decade ago now, we asked the reason why certain areas of the UK, which had undergone a thorough cull of badgers, had achieved such success.

The answer was unequivocal and needs to be inscribed over the door of every building occupied by this most political of government departments, and especially the office of the Secretary of State:

" The fundamental difference between the Thornbury area and other areas [] where bovine tuberculosis was a problem, was the systematic removal of badgers from the Thornbury area. No other species was similarly removed. No other contemporaneous change was identified that could have accounted for the reduction in TB incidence within the area" [157949 - Hansard]

Other areas too had spectacular success, including East Offaly, Steeple Lees and Hartland, but also the four area trial - [link] in Ireland with a reduction in cattle TB of around 96 per cent.

 And two decades or more ago, these areas had no bolt on cattle measures at all. Particularly of the sort Dr. May and his cohorts propose.

Just, as the PQ said 'a systematic removal of badgers from the area'.

Keep it simple.

 

RSPCA and the cull

From The Times - link] this morning: (The Times is paywall protected)

 "The RSPCA has softened its stance on badger culling by dropping a promise to publicly shame or investigate farmers who take part.
After years of threatening farmers with public disgrace and expulsion from its animal welfare schemes, it said it had accepted advice from “external auditors” that culling badgers was not an “automatic breach” of its ethical farming rules.

The audit was launched last year by its former chief executive, Jeremy Cooper. His predecessor, Gavin Grant, had threatened to “name and shame” farmers involved in the cull and said people would boycott milk “from farms soaked in badgers’ blood”.

 That's big of them isn't it?

 A previous headline could have been 'RSPCA promotes zoonotic Tuberculosis throughout it supplying farms'.

Beneficial crisis?

Most crises create casualties by the lorry load, but also beneficiaries - if you are cute enough to jump onto that particular bandwagon.  'Bovine' TB or zoonotic Tuberculosis as we prefer to label it, is no exception.
Hard on the heels of those reams of 'research' which we spoke about in this post - [link] comes a new initiative from animal health screening lab, BioBest.

 With a little help from Danielle Gunn-Moore, BioBest now advertise a screening test - [link] for Canine and Feline TB. Their sales sheet explains:

The interferon gamma test is intended to assist in the diagnosis of suspected canine and feline TB cases. The interferon gamma test can be useful in categorising cats and dogs with suggestive lesions. This in turn can inform decisions as to whether treatment is appropriate and whether it is necessary to report the case to AHVLA (Suspected Bovine TB is a notifiable disease in all mammals).

There is also some evidence that the test can be used to monitor treatment, with responses falling in cats in remission. The test has been developed in collaboration with Professor Danielle Gunn-Moore of the University of Edinburgh and with the technical support of colleagues from AHVLA.

It is to be hoped that the use of GammaIfn is somewhat more specific to zTB when used on cats and dogs, than its use has proved to be in cattle. False positives in that species are well documented.
And is 'treatment' of zTB, an often fatal zoonotic pathogen, in a companion animal, likely to be sharing air space, if not its owner's bed, a good idea?

But we digress..

We came across Professor Gunn-Moore in 2013, when she published articles giving a link to infected badgers and an increase in felines with TB. - [link] We remarked then, that with a veterinary post mortem on a cat costing in the region of £100, digging a hole may be cheaper.

 And we are also reminded of the genetic predictions made concerning feline encepalopothies in the 90s, when it was thought that Siamese / Burmese cats may be more susceptible. Until it was realised that the value of these animals made veterinary investigations more likely.

 BioBest say:

The test will initially be performed on the 1st and 3rd Thursdays of each month at a cost of £200 per sample.

That £200 per sample, would buy a truck load of cats. And it is unlikely that many owners taking up BioBest's offer of screening, will have offered unpasteurised milk to their pets..