Friday, May 18, 2018

About time too.

When a farm has a TB breakdown, much information is collated by the local veterinary offices. This includes slide samples (above) of bacteria present in any lesions. Sadly this is often dissipated between several APHA offices, but at some point it comes together as a report.

And better late than never, the farm's history of breakdowns, cattle movements and most importantly the genotype responsible for the breakdown, will be made available to the farm concerned.

 A newsflash from the NFU:
The APHA is making more data available to farmers in England and Wales to help tackle bTB.

Reports for individual farms are produced by the APHA using TB breakdowns and cattle movement data, these are posted out a few weeks after the start of a breakdown, with the aim of helping farmers better understand the bTB risks to their herd and to take action to reduce those risks.

 It is strongly recommended that farmers start to share these reports with their private vets which should help both parties to understand the level of bTB risk to the herd, the impact of previous TB breakdowns on the herd, the pattern of cattle movements and its potential effect on the herd's bTB risk, and also the reasons for the pattern of bTB breakdowns in the herd (if applicable).

The report describes the herd type and size, and any TB breakdowns that have occurred on the holding over the last 10 years, along with the causative strain (genotype) of bTB identified in the lab which shows the geographical area where that strain is commonly found.
This can help with identifying the route of transmission to establish if it is more likely to have come from cattle movements or indirect/direct contact with infected badgers.
And it is that final paragraph which is important.

When APHA culture samples from cattle taken as reactors, (and any badgers they feel like looking more closely at)  a genotype is revealed.
This, over many decades, has formed a database which we have described here, in 2006 -[link], and here with some charts - [link].

Each individual strain or spoligotype has slight variations if the sample is subject to VNTR (Variable Number Tandem Repeats) then these may be described as regional accents - [link] which a former Chief Scientist was delighted to 'discover'. They were there anyway, but until an 'ologist has found them, they remain unique but invisible.

 Farmers under TB restriction will also be offered a map - [link] of breakdowns in their area, including spoligotypes of the offending bacteria.

 Finally a thought for the day. The predominator strain of m.bovis (AN5) found decades ago, has now been eliminated, leading many scientists working on this subject to the question 'have we now got badger adapted TB - [link] spreading back up into our tested, sentinel cattle?