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TB trends in the badger cull areas

Recently a report was published by APHA which contains summary TB statistics for the first 10 licensed ‘badger control’ or cull areas. Click here to download this report.

These statistics are also viewable using the TB stats dashboard I have been creating. Click here to launch the dashboard and select ‘Badger cull areas’ on the left hand side panel.

The report contains measures of cattle TB incidence (the rate that new breakdowns occur) and TB prevalence (the % of herds under restrictions). These statistics are provided for the three years prior to each cull starting (this gives an idea of any trends or patterns prior to culling) and for each year during the culls.

The report covers up to the end of 2017, so provides data for the first 10 badger cull areas which started between 2013 and 2016. Cull areas licensed in 2017 and 2018 have not been underway for long enough for the data to be available, but they will be included in subsequent reports. The map to the right and table below show the details of the current badger cull areas active in England (in 2018).



Area number

County Year started size (km2)
1 Gloucestershire 2013 311
2 Somerset 2013 256
3 Dorset 2015 223
4 Cornwall 2016 393
5 Cornwall 2016 272
6 Devon 2016 431
7 Devon 2016 567
8 Dorset 2016 380
9 Gloucestershire 2016 651
10 Herefordshire 2016 285
11 Cheshire 2017 292
12 Devon 2017 563
13 Devon 2017 433
14 Devon 2017 249
15 Devon 2017 206
16 Dorset 2017 1030
17 Somerset 2017 280
18 Somerset 2017 198
19 Wiltshire 2017 623
20 Wiltshire 2017 546
21 Wiltshire 2017 332
22 Cornwall 2018 1272
23 Devon 2018 594
24 Devon 2018 510
25 Devon 2018 311
26 Devon 2018 303
27 Devon 2018 210
28 Devon 2018 194
29 Gloucestershire 2018 431
30 Somerset 2018 622
31 Staffordshire 2018 1180


Cumbria 2018




The statistics in this report are potentially quite interesting and give an idea of the TB trends in these areas, indicating whether TB is increasing, decreasing or stable. However, it is very important to note that on their own these data cannot tell us why these changes are occurring. This is clearly outlined by the authors of the report who state that “these data alone cannot demonstrate whether the badger control policy is effective in reducing bovine TB in cattle”. Unfortunately several organisations and individuals have ignored this and used these latest figures as evidence the cull are “working”. They may very well be working, but these latest statistics can not prove this for a number of important reasons.

If you look at any of the TB statistics (either in various reports, using the TB dashboard, or using ibTB) you can see that the numbers vary up and down over time and from area to area. It is therefore possible that TB could increase or decrease due to other factors which are unrelated to culling. This is clearly demonstrated by the fact that TB trends are often not stable in cull areas in the years prior to culling.

To demonstrate that culling is causing changes in TB in cattle we need to compare the rates or numbers of breakdowns in cull areas to areas without culling (see example below). There may be a benefit from culling (ie fewer TB breakdowns than would have occurred without culling) even if the raw trends in the data (ie the green arrow below) are decreasing, stable or even increasing (as the increase may be much less than in areas without culling, as in the bottom left graph – suggesting a benefit). Likewise, even if TB is decreasing this does not mean that culling is the cause, as it may have declined anyway due to other factors (as in the top middle and top right graphs).

The changes in TB incidence in the RBCT (randomised badger culling trial) were estimated by comparing areas with culling to matched controls without culling, producing the following results below (Taken from Godfray et al. (2013) ).

Again I stress that the above figures are changes in TB incidence (rate of new breakdowns) relative to the control areas without culling.

To date the only study that has compared TB incidence rates in cull areas to the comparison areas without culling is the study by Brunton et al. (2017) which uses only the first two years of data and is also summarised here. There are many limitations and caveats to this work, but to date this is the only evidence that that badger culling is causing changes in TB in cattle. An updated report/paper using four years of data is currently being prepared by APHA. Until then the data in this recent report may be interesting, but unfortunately they cannot answer the question “are the culls working?”.