Monday, May 30, 2005

Boys and Their Toys...

We closed the previous post with the observation (based on years of cynical involvement with the relationship between animal diseases and political expedience) that neither politicians nor politically motivated vets should be seen within a mile of any infectious bacteria. To that group we would add the new breed of animal, "Spatial Ecologists, using Mutiple Logistic Regressions", or Statistical Modellers as they are now quaintly entitled.

Readers may remember this new breeds first salvo into the murky world of animal disease and politics when, led by Townie Blurrs' chief scientist, Sir David King, the computers whirred and clanked and 11 million animals died in unholy circumstances for the want of some real expertise in genuine disease control. Ignored were Prof. Fred Brown and his Smart Cycler, (that was American for God's sake - what did you expect?) and world experts on FMD such as Dr. Simon Barteling, both of whom were imploring the Government to identify candidate infected animals with the PCR cycler and vaccinate the rest. Instead Bliar appointed this new scientific animal, a Statistical Modeller in the shape of Prof. Roy Anderson, who had no previous experience of animal disease control, but on the strength of computer input, 'modelled' to death over 8 million healthy animals in an illegal contiguous cull.

Now computers are great, but if in the input is wrong (spot the deliberate mistake in the previous paragraph - or was it?) then it's a case of 'crap in = crap out'. Which brings us to the much publicised piece in 'Nature' last week, which pumped cattle movements from the Cattle Movement Service (but little else) into a computer - and concluded in language which seemed to have been written with the serious intent of preventing anyone else understanding it, that cattle movements have caused the explosion of bTb.

Music to the ears of a Minister for Inertia (Margaret Beckett) who obviously paid a great deal of money for this paper which says much but means little - and of course the lovely Elaine King.

The paper starts with the staggering observation that bovine Tb's "Transmission pathways remain poorly understood".

We would point out with the greatest respect of course, that from 1895 (and that is not a typing error) the 'transmission pathways' of Tb have been explored, logged, and experimented with. Firstly in 1895 by Professor Koch of the London Public Health Laboratory, and during the whole of the last century by a raft of experts in infectious diseases. We know from answers to Parliamentary Questions, how much Tb bacteria is carried in badger urine, and the dosage needed to infect cattle in various ways. We know the survival rate of this bacteria under various circumstances, what carries it and the influence of environmental factors - and for those answers (all archived) as ever, we are most grateful. The collective brain cell of the Oxford team was obviously not party to all this 100 years of research, even though one member was influential some of it.

So what was entered into this exercise of 'spatial modelling' of bTb?
Cattle movements from the CTS database 2000 - 2003, and then backwards from 1997 - 2003. using the same data . This because " spatial and temporal patterns of movement were shown to be consistent from year to year". One might enquire, if such movements were 'consistent from year to year', what other variable was the cause of the rise in cattle Tb?
However, the paper goes on "Processing constraints and the current structure of the CTS database, prevented movement data to be generated on the fly during the simulation process as a function of the previous year's simulated distribution: it was therefore necessary to identify a surrogate variable for animal movements from previously infected areas".

You couldn't make that up - or could you?. Do we read this, that if data was unavailable from CTS, then a 'surrogate variable ' was substituted? Well, well, well. And they call this 'science'?

As well as cattle movements a few other hopefuls (out of a possible list of 100) were entered as predictor categories, including a "broad range of anthropogenic, biological, demographic, climatic and topograhic variables". The team describe "the mean of normalised deviation vegetation index". That sounds good doesn't it? Haven't a bloody clue what it means but..
Another gem, " encapsualted in Fourier-processed satellite imagery in modelling the distribution of bTb in Great Britain".

At least they 'paired' the movements, so they had caught up with one 'Off' and one 'On' equalling just a single movement. But did they exclude a movement to slaughter? The paper does not say.

The bits which this site finds most interesting - apart from what was left out of the modelling exercise - is the statement totally missed by industry commentators thusfar:

"the pattern of spread of bTb between 1984 and 2003 shows an expanding core.."
"short distance spread can be viewed as contagion to adjacent or nearby farms located within a few kms. by direct contact or bourne by wind, insects, rodents or alternative hosts".

"movements are more important for the spread of infection than for its persistence.".


M. bovis although a tenacious little bug may arguably be excluded from all but two of the hypotheses given for contagions by the Oxford teams which is confirmed as "short distance spread from an expanding core".

The paper continues, "long distance jump-spread can be viewed as contagion occurring between locations separated by large areas of disease absence, and caused by the movement of infectious individuals or material".

Fairly profound that one, but we get the picture. But let's not forget the translocation of the other part of the infection cycle - to parts of the country where they are not likely to be ' persecuted'. It's not just cattle that move. Badgers translocated in cage traps are a disease opportunity - a Tb takeaway.

Despite the attention grabbing headlines of this 'work', another observation conveniently ignored by the mainstream media concerns such long distance movements of cattle;
"It should be pointed out that ...there are several regions into which many animals are imported and where the disease appears regularly but does not seem to persist. Potential explanations include ...the imported animals remain there only a short time before being slaughtered, and that suitable wildlife reservoirs do not exist in those areas or the conditions necessary for the establishment in those species are not fulfilled".

So they got there in the end. But conclude that their work has 'established a clear requirement for further examination of cattle movements to define the critical movement categories.."

Are they are asking for more money?

BCMS confirm that our Matthew 5 has had 'No 'ON' movements of bought in cattle ' onto his farm. The farm, as with two of our other editors is ring fenced to prevent cattle / cattle contact, yet we have all watched that "expanding core" of disease creep nearer and engulf our herds. And stay there.

The headline of the Oxford work is 'Cattle Movements and Bovine tuberculosis in Great Britain'.

What part of 'No 'ON' movements' do these people not understand?

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