Bovine TB. Crunching the numbers.
Bovine TB or bTB is a very nasty disease. For people and for animals both domestic and wild. For that reason it's a notifiable disease, which means if you have a case on your farm you have to tell the government. Combined with a stringent and regular testing programme for cattle we have a remarkable amount of data on the disease.
Well usually. But thanks to a computer glitch at the Animal Health and Veterinary Laboratories Agency in Worcester we haven't had any new data since September 2011. It seems odd that the government has announced a cull of badgers to tackle bTB and we don't actually have an up to date picture of what is going on.
But if we take the assurances of Defra and Animal Health and Veterinary Laboratories Agency at face value then this lack of data isn't a problem for the cull and they have promised it will soon be resolved.
Which brings us to the badger cull and the science behind it. The headline facts show that bTB is a huge problem for Britain's cattle farmers. This is from Defra's own website.
"Nearly 25,000 cattle were slaughtered in England last year alone because of bovine TB, with the cost to the taxpayer set to top £1 billion over the next ten years. The problem is particularly bad in west and south-west England, where nearly a quarter of all cattle farms were affected by the disease during 2010."
With a cull happening here in the Midlands what is the disease doing here? Well we can break things down county by county thanks to all that data collected by Defra which you can find here
These two graphs show the number of cattle slaughtered to control the disease in the Midlands and the number of herds affected by movement restrictions put in place because the disease has been detected. I've selected the data from 2002 onwards since the foot-and-mouth crisis in 2001 caused all sorts of problems with bTB testing. Even without the latest data we can still observe much from the trends over eight years.
In the Midlands overall, however you measure it, bTB is a growing problem with a clear upward trend in the worst affected counties. Indeed Staffordshire and Shropshire show particularly alarming rises over the past eight years.
Is there perhaps some good news in that the last few years show a dip in terms of cattle numbers slaughtered for some counties? It will be very useful when the data for 2011 is finally released to be able to say more about this. But at the moment it's hard to be hopeful, indeed this drop might just be down to the fact there are fewer cattle around to slaughter. Cow numbers are declining as farmers in the dairy sector continue to struggle, not least because of bTB.
So the data (well what we have!) shows there is clearly a problem. In the next post I look at whether a cull is the right solution.