Concern Over Use of Statistics in TB Campaign
According to Dr Glossop, while recently there has been a welcome decline in the monthly TB statistics, the historical trend is still upward. The assertion by the Badger Trust that the fall in the numbers is “in line with longer-term statistics showing a consistent downward trend of about seven percent over the last two and a half years both in Wales and Great Britain as a whole” is therefore untrue.
In her letter to the Badger Trust, Dr. Glossop said: “While any reduction in the TB statistics is welcome, it would be premature to suggest a turning point has been reached, based on the available data. Statistics must be used and interpreted with care and the TB statistics need to be analysed over time to observe a trend. TB is a long term epidemic and historically the trend has been upwards. We have seen short term falls before – for example in 2004 and 2006.
“As much as we would like to take credit for the recent decrease observed in the Welsh TB statistics, it is far too early to say whether the stricter cattle controls, increased testing and our zero tolerance approach to not complying with regulations are making a difference."
In her letter the Chief Vet included charts of the number of animals slaughtered and the number of confirmed new incidents each quarter for Wales and the whole of Britain from 2007 to 2010 extracted from the National Statistics. The charts reinforce the danger of trying to identify short term trends and turning points in the presence of such huge variation.
The main picture is a highly variable series with large variations around any underlying trend. The main messages are:
- The levels of TB remain unacceptably high;
- The number of animals slaughtered in quarter 4 2008 and quarter 1 2009 seem high compared to the rest of the series, particularly in Wales;
- Results for later 2009 and 2010 are broadly in line with similar periods in 2007 and 2008.
RUMA CA&E has extended the deadline for its online survey into vaccine availability.
