Saturday, January 21, 2017

If it's good enough for the Aussies??

A new and said to be 'highly reliable' diagnostic solution - [link] for bovine tuberculosis, a major infectious disease among cattle, other farm animals and certain wildlife populations, is now on the market, reports Vet Practice magazine (Australia)
“The VetMAX M. tuberculosis Complex PCR Kit is a reliable and fast tool to confirm the presence of mycobacteria belonging to the tuberculosis complex,” said Martin Guillet, global head and general manager of AgriBusiness at Thermo Fisher Scientific, the company that has developed what is the only commercially available PCR test that detects all seven strains of the M. tuberculosis complex in a single solution.
Using the test on suspect cattle lesions, the article explains that results using this PCR approach can be returned much faster when compared to bacterial culture testing methods. While the results of a M. bovis culture can take up to six weeks, results using PCR—from sample preparation to testing—take just three hours.

 And we note that the same kit (VetMax M. tuberculosis Complex PCR) was trialed in 2014 alongside conventional culture testing on abattoir suspect lesions, in France - [link] This is the result:
The aim of this study was to estimate and compare sensitivities and specificities of bacteriology, histopathology and PCR under French field conditions, in the absence of a gold standard using latent class analysis.

The studied population consisted of 5,211 animals from which samples were subjected to bacteriology and PCR (LSI VetMAX™ Mycobacterium tuberculosis Complex PCR Kit, Life Technologies) as their herd of origin was either suspected or confirmed infected with bTB or because bTB-like lesions were detected during slaughterhouse inspection.

Samples from 697 of these animals (all with bTB-like lesions) were subjected to histopathology. Bayesian models were developed, allowing for dependence between bacteriology and PCR, while assuming independence from histopathology.

The sensitivity of PCR was higher than that of bacteriology (on average 87.7% [82.5–92.3%] versus 78.1% [72.9–82.8%]) while specificity of both tests was very good (on average 97.0% for PCR [94.3–99.0%] and 99.1% for bacteriology [97.1–100.0%]). Histopathology was at least as sensitive as PCR (on average 93.6% [89.9–96.9%]) but less specific than the two other tests (on average 83.3% [78.7–87.6%]).

These results suggest that PCR has the potential to replace bacteriology to confirm bTB in samples submitted from suspect cattle.
As regular readers will have guessed, we are fans of PCR diagnostics - [link] both for speeding up diagnosis in cattle lesions, and having pushed government to support its use, identifying infection in badgers.

So were somewhat floored by the reaction of its British developers - link] (scroll forward on the video to 20 minutes in to see that reaction which we have pasted below.)
" I’m extremely busy and it’s difficult to find time to watch the film as it is long, however, I have just watched it and I don’t feel I can be involved in the film as the tone and message are not in line with my views. Some of what has been said is unscientific, including some of the comments from your vet. Also, you have criticised scientists at least twice in 5 minutes. I am not pro cull and I do not believe the evidence supports culling badgers, even in the case of your farm. I do hope you understand that the tone of this video and the content is not in agreement with my views so I cannot be involved. "
We get the picture. Follow the money, and the 'group conformity' to keep zoonotic tuberculosis rolling  - in GB at least.

But if PCR diagnostics is good enough for the Aussies, and results compare very favourably with bacterial cultures in France and also in a privately funded study into zTB in alpacas - [link] why not here too?

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