Research and analysis

Background information: badger control areas monitoring data up to 2023

Published 16 October 2024

Purpose of the monitoring data

APHA is commissioned by Defra to monitor the incidence of bovine tuberculosis (TB) in cattle in geographic areas where badger control has been undertaken under specific licence for culling. To address this requirement APHA publishes monitoring data showing the incidence and prevalence of TB in cattle herds in badger control areas for which there is at least one year of follow-up after at least one period of culling.

The data are provided in an accessible format in OpenDocument Spreadsheets (ODS). This document provides background information and methodological details to accompany these data.

The monitoring data are derived from TB tests conducted during routine surveillance and control of TB in cattle. The data do not demonstrate whether the badger control policy has reduced bovine TB in cattle. Evaluation of the effect of the badger control policy requires consideration of other factors that could affect cattle TB incidence in addition to culling. This has been subject to separate independently reviewed and published analytical studies (Brunton et al., 2017; Downs et al., 2019; Birch et al., 2024).

The badger control policy

Bovine tuberculosis (TB) is an infectious, zoonotic (can infect humans) bacterial disease of cattle and other mammals (About bovine TB), with a significant wildlife reservoir (badgers) present in large areas of England. The badger control policy was introduced in England to reduce the population of badgers where TB is endemic. The aim was to reduce the potential for transmission of Mycobacterium bovis, the bacterium that causes TB, between badgers and cattle, and hence reduce the incidence of TB in cattle. The policy was informed by evidence generated from the Randomised Badger Culling Trial (RBCT) conducted in England between 1998 and 2005 (Donnelly et al., 2007; Jenkins et al., 2010).

Further information on the badger control policy and how badger culling helps deliver the aim of Officially TB Free (OTF) status for England can be found in the following publications: The Government’s policy on Bovine TB and badger control in England and a strategy for achieving Officially Bovine Tuberculosis Free status for England.

The badger control policy includes licensed industry-led badger culling in England (Defra, 2021) since 2013 and provision of biosecurity advice to farmers in licensed areas since 2014.

Since the badger control policy was first implemented, there have been some changes to other TB surveillance and control policies which apply to cattle in badger control areas. These are listed in the Changes to TB surveillance that can affect TB incidence and prevalence section.

There are currently three types of badger culling licence in use in England:

1. Badger Disease Control licence. These are applicable to the High Risk Area (HRA) and Edge Area of England and have a duration of four years. The period of badger culling under these licences is referred to as the “intensive” cull period.
2. Supplementary Badger Disease Control licence. These are applicable to areas that have already completed at least four years of culling under a Badger Disease Control licence. Duration of the licence has varied between areas, with a maximum of five years.
3. Low Risk Area Badger Disease Control licence. These are applicable to the Low Risk Area (LRA) of England and typically associated with TB control within defined TB hotspots. These licences are subject to an annual evidence review by APHA epidemiologists, ecologists, and the Chief Veterinary Officer (CVO) to ensure the ongoing suitability of badger control.

During the reporting period, all badger culling licences were issued by Natural England (NE). These licences were issued under the Protection of Badgers Act 1992. Licences apply to pre-defined badger control areas, the boundaries of which were defined by NE.

Badger control areas in the HRA and Edge area were selected by the farming industry and must meet government licensing criteria. In 2013, areas were required to be greater than 150 km² with at least 70% of land accessible for culling (note that ‘accessible land’ comprises land parcels owned by landowners participating in the cull). Following a consultation on guidance to Natural England on licences to control the risk of bovine tuberculosis from badgers in 2015, the licence criteria were adjusted to 100km² minimum area size with at least 90% of land accessible for culling (Defra, 2021). Badger control areas in the LRA were defined by expert epidemiologists and ecologists according to established criteria for managing TB hotspots.

Under a Badger Disease Control licence (including in the LRA), culling took place for a period of approximately six weeks between late August and early November until badger removal targets were met. Culling operations under a Supplementary Badger Disease Control licence were authorised to take place over a longer time period, generally from June to the following January. More detailed information relating to operations in badger control areas up to the end of 2023 can be found at: Summary of 2023 badger control operations, Summary of 2023 supplementary badger control operations and Bovine TB: hotspots in the Low Risk Area of England.

Badger control areas included in the latest monitoring data

The latest monitoring data include data up to the end of 2023 for all areas licenced up to and including 2022 (72 areas in total). Two licences were issued in 2012 (although the badger cull began in 2013), one licence in 2015, seven licences in 2016, 11 licences in each of 2017, 2018, 2019 and 2020, and seven licenses in 2021. A further 11 licences were issued in 2022. The majority of areas are located in the HRA, but 15 straddle the HRA and Edge Area, and eight are located entirely in the Edge Area. Two are located entirely in the LRA for TB in England (linked to TB Hotspots) with licences issued for Low Risk Area Badger Disease Control purposes (Area 32 and Area 54).

As of the end of 2023, badger culling operations remained active in 58 of the badger control areas covered in this report (Summary of 2023 badger control operations, Summary of 2023 supplementary badger control operations). Licensed badger culling operations concluded in Areas 01, 02 and 32 at the start of 2022, and in Areas 11 to 21, inclusive, at the start of 2023. An overview of badger control operations in each area is shown in the accompanying ODS spreadsheet, Badger control areas overview.

Each badger control area has a unique identifier, which relates to when the area was first licensed for badger culling and the county in which it is located. The boundaries of these areas are defined and provided by NE to APHA each year. The total size (km²) of each area when licenses were first issued by NE are shown in Table 1, and are taken from the publications ‘Setting the minimum and maximum numbers in badger cull areas’ for each licensing year found on Bovine TB: Policy papers and consultations.

Badger control area boundaries have remained broadly stable over time, with revisions to some areas’ boundaries by NE, most often in the second or third year of the Badger Disease Control licence. Once boundary revisions were approved, they were first implemented operationally during the following badger cull season. The percentage changes to the size of badger control areas over time due to boundary revisions are shown in Table 1. Boundary revisions made up to and including 2022 are reflected in the current monitoring data.

Table 1: Total area size (km²) and percentage area changes to badger control areas licensed up to and including 2022.

Areas linked to Low Risk Area hotspots are identified by “HS” number in parentheses. Total area size (including accessible and inaccessible land) on the date each area was first issued with a licence is shown. The percentage area changes to the size of badger control areas over time due to boundary revisions and the dates these boundary revisions were approved are also shown.

Badger control area	Total area size (km2)	Percentage area changes
Area 01 - Gloucestershire	311	No change
Area 02 - Somerset	256	No change
Area 03 - Dorset	223	No change
Area 04 - Cornwall	393	No change
Area 05 - Cornwall	272	No change
Area 06 - Devon	567	No change
Area 07 - Devon	431	No change
Area 08 - Dorset	416	+ 3.2% in April 2017
Area 09 - Gloucestershire	649	No change
Area 10 - Herefordshire	285	No change
Area 11 - Cheshire	292	No change
Area 12 - Devon	563	No change
Area 13 - Devon	433	+ 9.4% in May 2018
Area 14 - Devon	249	No change
Area 15 - Devon	206	+ 0.6% in May 2018
Area 16 - Dorset	1030	No change
Area 17 - Somerset	280	No change
Area 18 - Somerset	198	No change
Area 19 - Wiltshire	623	+ 3.5% in May 2018
Area 20 - Wiltshire	546	+ 1.3% in May 2018
Area 21 - Wiltshire	332	No change
Area 22 - Cornwall	1272	No change
Area 23 - Devon	594	No change
Area 24 - Devon	510	+ 6.1% in February 2019
Area 25 - Devon	311	No change
Area 26 - Devon	303	No change
Area 27 - Devon	210	No change
Area 28 - Devon	194	No change
Area 29 - Gloucestershire	431	No change
Area 30 - Somerset	622	No change
Area 31 - Staffordshire	1180	No change
Area 32 – Cumbria (HS21)	190	+12.7% in January 2019
Area 33 - Avon	480	No change
Area 34 - Cheshire	515	+19.8% in August 2020
Area 35 - Cornwall	1021	+0.3% in August 2021
Area 36 - Staffordshire	289	No change
Area 37 - Devon	548	0.3% in August 2020
Area 38 - Devon	509	No change
Area 39 - Dorset	390	No change
Area 40 - Herefordshire	1119	+0.3% in August 2020
Area 41 - Staffordshire	455	No change
Area 42 - Wiltshire	1076	No change
Area 43 - Wiltshire	547	No change
Area 44 - Avon	561	+24.2% in August 2021
Area 45 - Derbyshire	761	No change
Area 46 - Gloucestershire	222	+4.6% in August 2022
Area 47 - Herefordshire	557	+11.5% in August 2021
Area 48 - Leicestershire	392	No change
Area 49 - Oxfordshire	607	No change
Area 50 - Shropshire	1551	+1.1% in August 2021 +1.2% to 2021 area in August 2022 (2.3% increase from original area)
Area 51 - Somerset	606	+3.0% in August 2021 +1.3% to 2021 area in August 2022 (4.4% increase from original area)
Area 52 - Warwickshire	607	+11.8% in August 2021
Area 53 - Wiltshire	251	+4.6% in August 2021 +1.1% to 2021 area in August 2022 (5.8% increase from original area)
Area 54 - Lincolnshire (HS23)	102	+19.1% in August 2021
Area 55 - Shropshire	181	+9.8% in August 2022
Area 56 - Hampshire	450	+3.5% in August 2022
Area 57 - Berkshire	133	+0.5% in August 2022
Area 58 - Staffordshire	234	+0.8% in August 2022
Area 59 - Worcestershire	117	No change
Area 60 - Shropshire	547	+31.5% in August 2022
Area 61 - Oxfordshire	324	+23.4% in August 2022
Area 62 - Buckinghamshire	252	No change
Area 63 - Cornwall	103	No change
Area 64 - Cornwall	104	No change
Area 65 - Derbyshire	258	No change
Area 66 - Devon	151	No change
Area 67 - Hampshire	153	No change
Area 68 - Northamptonshire	501	No change
Area 69 - Oxfordshire	211	No change
Area 70 - Somerset	100	No change
Area 71 - Warwickshire	252	No change
Area 72 - Warwickshire	534	No change

APHA-delivered badger vaccination in badger control areas

APHA have been delivering badger vaccination across parts of England since 2010, but until 2020 these projects have been relatively small scale, with the exception of the Badger Vaccine Deployment Project (APHA, 2015). In 2020, APHA vaccination began in Area 32, which is linked to an LRA hotspot. Since 2021, the scale of vaccination operations elsewhere has increased, and APHA-delivered vaccination has now been carried out within the boundaries of some badger control areas located in the HRA and Edge areas. Up to the end of 2023, APHA badger vaccination operations covering at least 1km² had been carried out in parts of 16 badger control areas.

Badger vaccination requires a separate licence to badger culling under the Protection of Badgers Act 1992, which are issued by Defra and NE (Licences to cage-trap and mark badgers for bovine TB vaccination). Licences permit cage trapping of badgers for the purpose of vaccination between 1 May and 30 November each year. You can find further details of badger vaccination licensing criteria and field operations on Bovine TB control: licence to take and mark badgers to enable vaccination.

The extent of land within the boundaries of each badger control area where landowners had signed up for APHA-delivered badger vaccination by 31 December each year is given in the accompanying ODS spreadsheet, Badger control areas overview. This includes any land where landowners had signed up for badger vaccination, even if vaccination did not subsequently take place due to an absence of badger activity. Where the amount of land signed up to vaccination was very small within an area, this primarily occurred at area margins and was associated with a larger badger vaccination effort occurring outside of the area’s boundaries.

For ten of the 16 areas, the size of land subject to APHA-delivered vaccination was relatively small, but vaccination operations were more extensive (covering more than 10km²) in six areas. In three of these areas, vaccination took place while badger cull operations were still ongoing: in Area 32 (linked to TB Hotspot 21 in the LRA) in 2020-2021, in Area 19 in 2021-2022, and in Area 30 in 2022-2023. Vaccination was also applied to parts of five of the six areas once badger culling operations had ended: in Areas 01, 02 and 32 in 2022-2023, and in Areas 19 and 20 in 2023.

Licensed badger vaccination projects delivered by non-government organisations have also been carried out in parts of England since 2010. Activity has taken place across all TB risk areas, including within the boundaries of some badger control areas. However, most of this activity has been small scale. Detailed information about which land was signed up to badger vaccination by non-government organisations is not currently routinely available to APHA. Data on the occurrence of non-APHA-delivered badger vaccination are therefore not included with the data we present here. This may result in a slight under-estimate of the overall land area that was signed up for badger vaccination in some badger control areas.

The total number of badgers vaccinated per county across England in 2023 can be found on: Summary of badger vaccination in 2023.

Comparison of badger control operations in each area over time

The ODS spreadsheet, Badger control areas overview, provides an overview of the badger control activities occurring in each area up to the end of 2023, including the years in which badger culling took place, and the extent (km²) of APHA-delivered badger vaccination occurring within each area.

Information about badger culling and badger vaccination is presented on a calendar year basis to enable simple comparison, but it should be noted that the badger culling and badger vaccination seasons do not start on 1 January. Occurrence of culling is depicted as having first occurred in an area in the year that it was first licensed, even though it will have generally begun around late August to early September of that year. The extent of badger vaccination in an area for a given year is shown as the total km² of land parcels (rounded to the nearest whole number) signed up for APHA-delivered badger vaccination between 1 January and 31 December of that year.

Due to differences in licence conditions, badger culling and badger vaccination activities took place at different times during each calendar year, though potentially with some temporal overlap. Therefore, even if both types of badger control took place in the same badger control area during the same year, they may not have always occurred in parallel. It should also be noted that since not all land within the boundary of a badger control area may have been accessible for culling, badger vaccination occurring within an area may not necessarily have been deployed on land that was always itself previously culled.

Changes to TB surveillance that can affect TB incidence and prevalence

Reported incidence and prevalence of TB reflects the background force of infection but also surveillance and control policies, which affect the detection of disease. Surveillance and control policies, including the frequency of routine testing for TB in cattle and the types of tests applied, can differ across the TB risk areas and therefore can differ between badger control areas. The main changes to TB surveillance and control policies up to the end of 2023 affecting cattle in badger control areas are listed below. Further information about TB tests and surveillance and control policies can be found on the TBhub.

1. Prior to 2013, when the badger control policy started, most cattle herds in counties now in the HRA were subject to routine annual field surveillance for TB using the tuberculin skin test. Most counties in the Edge Area, as it is now known, were subject to field surveillance every two years, although there was some variation in this.
2. In 2013 all herds in the Edge Area became subject to routine annual surveillance.
3. In 2015 part of the county of Cheshire in the Edge Area became subject to routine 6-monthly testing because the area was recognised as having a particularly high risk of infection.
4. In 2018 routine 6-monthly testing was applied to all of Cheshire, Oxfordshire and Warwickshire, and parts of Berkshire, Hampshire and Derbyshire in the Edge Area (Expansion of the Edge Area and cattle testing arrangements).
5. In September 2020 routine 6-monthly testing was applied to the HRA counties of Staffordshire and Shropshire.
6. In July 2021 routine 6-monthly testing was applied to the remainder of the HRA (Animal and Plant Health Agency, 2021a; Six-monthly surveillance testing of cattle herds in the HRA). Herds in counties subject to 6-monthly testing can revert to annual testing upon meeting criteria which demonstrates a lower risk of infection (Earned Recognition).
7. From 2017 to 2021, mandatory interferon (IFN) gamma testing to detect and remove infection was applied to persistent confirmed TB incident herds in all risk areas, and to all new confirmed TB incidents in the LRA and Edge Area. In the HRA, IFN gamma testing was also applied to herds with a new confirmed TB incident where cattle to cattle transmission was considered the most likely route of infection or when herds were located in areas that had been subject to two or more years of badger culling.
8. Since July 2021, the gamma testing policy has changed in the HRA and six-monthly testing Edge Area, where IFN gamma testing is now applied to all herds experiencing a new confirmed TB incident within 18 months of the herd regaining OTF status following a previous incident (Refinements to the IFN gamma testing policy in the HRA and Edge Area). The policy remains the same for the annual testing Edge Area and the LRA.
9. From 23 March 2020, skin testing for select purposes was not mandatory for cattle under 180 days old due to the COVID-19 outbreak (Advice for OVs on a temporary amendment to testing bovine animals under 180 days old in Officially TB-Free herds in England and Wales during the COVID-19 outbreak). Short interval tests, which are required to restore a herd’s OTF status, were not originally included in this derogation. However, herds were considered on a case-by-case basis with extensions granted to time windows to perform short interval tests (Advice for OVs undertaking TB testing during the COVID-19 outbreak in England). These temporary amendments to TB skin testing due to COVID-19 were discontinued in July and August 2021 (Discontinuing Covid-19 temporary amendments to TB skin testing in GB).
10. During the winter of 2022/2023, a large-scale outbreak of highly pathogenic avian influenza (HPAI) meant that substantial numbers of APHA personnel were redeployed from usual TB surveillance activities to help control the outbreak. However, there were established contingency plans in place to minimise disruption to TB control activities in England (Delivery of TB surveillance & controls during the HPAI outbreak (England)).
11. From 1 August 2023, post-movement TB testing became compulsory for cattle moved to annual surveillance testing parts of the Edge Area from higher TB incidence areas of England, and from Wales. A small number of exemptions apply (Post-movement testing in annual surveillance testing parts of the Edge Area).

Monitoring methods

Data source and quality

TB data are extracted from Sam, the APHA database, which records the results from TB tests conducted in cattle herds throughout Great Britain. Data were downloaded on 10 April 2024.

These data are compiled from TB surveillance activities and control policies, and historical data may be updated or corrected over time. Corrections may include removal of a herd that has become inactive, inclusion of a herd that has become active, and revisions to the geographical location of the herd. Herd TB incident designation may also change from unconfirmed infection (Officially Tuberculosis Free- Suspended, OTF-S) to confirmed infection (Officially Tuberculosis Free- Withdrawn, OTF-W) due to confirmatory information about the presence of M. bovis infection becoming available since the previous report was published. Data corrections and routine validation can affect the counts of incidents and the calculated time at risk. The corrections in the past have generated minor differences in statistics between annual reports, particularly in relation to the year prior to the most recent year in the report. The most recently published monitoring data contain the most accurate current and historical data known to the project team.

Time period

Monitoring data are provided for calendar years and intervention years. Each badger control area has its own associated baseline date, which is the start date of the first cull in that area. An intervention year is the period of 12 months starting from the same day and month of the baseline date for each year in the reporting period and is defined separately for each area. Note that intervention years are always based on the start date of culling and are not influenced by the occurrence of any badger vaccination occurring in an area.

The starting year reported, and the number of follow-on years is dependent on when the start date of the first cull in that area took place. Data up to four years prior to the baseline date for each badger control area are also included.

Monitoring herd populations

Data are reported for two different cattle populations: cohort and herds in existence (HIE). The populations represent alternative definitions of cattle herds exposed to badger culling. Each is subject to potential sources of bias.

Cohort

Cohort herds are herds recorded as active in badger control areas on the baseline date for that area. The number of herds in the cohort population is affected by changes in the active status of herds in the original cohort over time, for example, the loss of herds from farms that are no longer operating. This means the number of herds in the cohort can decrease but not increase between years following the first year of culling in that badger control area. The cohort population is not affected by changes to cull area boundaries.

By their definition, we can assume that cohort herds are exposed to badger control operations for the full follow-up period whilst they remain active. However, loss of herds from the cohort population over time appears to be non-random and may be a substantial source of bias, as herds most likely to cease to exist tend to have lower TB incidence rates than herds that remain in the cohort (Birch et al., 2024).

Herds in existence (HIE)

HIE provides an annual snapshot of active herds located within each badger control area in each reporting year. This group of herds includes active cohort herds plus other herds recorded as active within an area each year based on contemporary herd location map reference data. The size of the HIE population may therefore fluctuate over time and herd identity is not static. HIE may therefore include herds that were not in a badger control area for the entire follow-up period (for example, if they only became active after the baseline date), or at all (for example, if they were only active before the baseline date).

When the annual monitoring data are compiled, HIE are retrospectively redefined for each reporting year for each area to account for ongoing data validation (see Data Source and Quality). In addition, HIE for all reporting years is based on the most up-to-date boundary information provided by NE so that it always includes active herds located within the maximum area to have been culled under licence for each badger control area. This means that HIE for all years are also retrospectively redefined annually at the time of data compilation to account for any changes to badger control area boundaries that may have occurred up to the preceding year. Note, however, that updates to HIE resulting from a boundary extension are not implemented in the dataset until one season of badger culling has taken place within the extended area. These retrospective changes may result in minor differences in the HIE data reported between data releases.

HIE aims to represent all herds currently exposed to badger control operations at a given point in time. However, herds included in HIE each year were not all active on the baseline date for the area. Some herds may therefore have not been exposed to badger control operations for the entire follow-up period and the inclusion of herds that only recently became active may be a source of bias.

Individual area monitoring data

The monitoring data include the following metrics, calculated for each badger control area: total number of incidents, number of OTF-W incidents, number of herds, herd years at risk, OTF-W incidence, OTF-W prevalence and numbers of reactors. Each metric is calculated for two different annual surveillance units: intervention years and calendar years. Each metric is calculated for two different cattle populations: cohort herds and HIE. 

Values in cells representing data for areas with fewer than 10 herds in total have been omitted to ensure the confidentiality of individual herd owners. This cut-off value is used by the Office for National Statistics (ONS) (Office for National Statistics, n.d.; Welpton, 2019).

Glossary of definitions for the monitoring data

Baseline date 

The baseline date is the start date of the cull in each area.

All incidents and OTF-W incidents

All incidents refer to the total number of TB incidents (newly detected infection) in a herd during the reporting period, that is the intervention year or calendar year. It is the sum of Officially Tuberculosis Free-Withdrawn (OTF-W) and Officially Tuberculosis Free-Suspended (OTF-S) incidents detected. Both OTF-W and OTF-S are incidents of TB in a herd that have been disclosed through TB surveillance. However, in OTF-W incidents, M. bovis infection has been confirmed through post-mortem tests in at least one animal from the herd. For incidence data, incidents refers to the number of incidents detected throughout the reporting period. For prevalence data, the incidents refers to the number of incidents on the last day of the reporting period (intervention year or calendar year).

Number of herds

The number of herds refers to the number of active herds in a badger control area for each group (cohort or HIE) at either the start (for incidence) or end (for prevalence) of each reporting period, that is the intervention or calendar year.

Time at risk (TAR)

The TAR is the total period of time the herds in a badger control area were considered at risk of TB infection (Defra, 2015; Downs et al., 2013). Herds are considered to be at risk of infection when they are not under trading restrictions because of TB infection (that is, an incident) in the herd. The TAR is reported in years and is calculated from day one of the reporting period to the final day of the reporting period.

OTF-W incidence rate

The OTF-W incidence rate is the rate of occurrence of new OTF-W incidents over the reporting period. The rate is calculated as the number of new OTF-W incidents divided by the TAR and is reported as incidents per 100 herd years at risk (Defra, 2015; Downs et al., 2013). OTF-W incidence rate is used as the primary outcome for monitoring rather than total TB incidence rate (which includes OTF-W and OTF-S incidents). Stronger associations have previously been shown between OTF-W incidence rate and badger culling (Donnelly et al., 2007, Downs et al 2019). OTF-W incidence rate is less sensitive to variation in surveillance intensity than OTF-S incidence rate. Temporal changes to OTF-W incidence rate are also countered to some extent by linked and opposite changes to OTF-S incidence rate and monitoring total incidence rate disguises these underlying dynamics.

OTF-W prevalence

The OTF-W prevalence is a point prevalence measurement indicating the proportion of herds under trading restrictions due to an OTF-W incident on the last day of each reporting period. OTF-W prevalence provides an indication of the burden of disease in a badger control area.

Skin test reactors

Skin test reactors are cattle that reacted to the Single Intradermal Comparative Cervical Tuberculin (SICCT) test, which is the primary screening test for TB in cattle in the UK. The yearly count of reactors relates to the date reactors were detected, not necessarily the year the incident started. Therefore, the count can include reactors from incidents which started in previous years.

The data do not include any cattle removed as “Direct Contacts (DC)”. These are non-reactor animals which are slaughtered because they are considered to be at high risk of being infected, normally as a result of contact with infected cattle.

Interferon (IFN) gamma reactors

IFN gamma reactors are cattle that tested positive to the IFN gamma assay, which is a rapid whole blood in-vitro assay to detect immune response to M. bovis infection for the diagnosis of bovine TB.

Antibody test reactors

Antibody test reactors are cattle that tested positive to an antibody detection assay, which detects whether the animal is generating an immune response to a current M. bovis infection.

Reactors to the SICCT test, the IFN gamma assay and the Antibody test are included within the count of skin test reactors but are not included within the count of IFN gamma or Antibody test reactors. Reactors to both the IFN gamma assay and the Antibody test (but not the SICCT test) are included within the count of IFN gamma reactors but are not included within the count of Antibody test reactors. These counts include all reactors detected during a breakdown, including any at a short interval skin test.

Changes to the monitoring data and background information over time

1. Since the 2018 publication, no data from unculled comparison areas are included because of the loss of land (to culling) which might have been used to compare TB incidence rates in cattle to rates in badger control areas.
2. Since the 2021 publication, TB and herd data are no longer reported for buffer areas surrounding central badger control areas. This is because over time the proportion of the buffer area remaining around badger control areas has decreased, with substantial deductions in some areas (Animal and Plant Health Agency 2021b, Table 1) due to the licensing of new badger control areas. Additionally, remaining buffer is often comprised of small, separated areas of land which contain small numbers of herds. The overall reduction of available buffer land and the division of remaining buffer into small segments diminishes its value in an analysis of effects from culling.
3. Since the 2022 publication, figures are no longer included to display the monitoring data due to the large number of areas now reported. All data which were displayed in the figures are still available in the OpenDocument Spreadsheets.
4. Since the 2022 publication, 95% confidence intervals are no longer provided with the monitoring data. This is to allow data users to calculate confidence intervals using their preferred method.
5. Since the 2024 publication, an additional OpenDocument spreadsheet is provided to give an overview on the different badger control operations (badger culling and APHA-delivered badger vaccination) that have occurred in each area over time.

Bibliography

Animal and Plant Health Agency (2015) Badger Vaccine Deployment Project. Final Lessons Learned Report.

Animal and Plant Health Agency (2021a) Approach to Setting Routine Surveillance TB Testing Intervals in 2021 Policy Document for England.

Animal and Plant Health Agency (2021b) Bovine TB: incidence of TB in cattle in licensed badger control areas in 2013 to 2020.

Birch, C.P.D., Bakrania, M., Prosser, A., Brown, D., Withenshaw, S.M., Downs, S.H. (2024). Difference in differences analysis evaluates the effects of the badger control policy on bovine tuberculosis in England. Sci Rep 14, 4849.

Brunton, L. A., Donnelly, C. A., O’Connor, H., Prosser, A., Ashfield, S., Ashton, A., Upton, P., Mitchell, A., Goodchild, A. V, Parry, J. E., & Downs, S. H. (2017). Assessing the effects of the first 2 years of industry-led badger culling in England on the incidence of bovine tuberculosis in cattle in 2013–2015. Ecology and Evolution, 7(18), 7213–7230.

Defra. (2015). Headline statistic on herd incidence : incidents per 100 herd-years at risk.

Defra. (2021). Guidance to Natural England Licences to kill or take badgers for the purpose of preventing the spread of bovine TB under section 10 (2) (a) of the Protection of Badgers Act 1992.

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Downs, S. H., Clifton-Hadley, R. S., Upton, P. A., Milne, I. C., Ely, E. R., Gopal, R., Goodchild, A. V, & Sayers, A. R. (2013). Tuberculin manufacturing source and breakdown incidence rate of bovine tuberculosis in British cattle, 2005–2009. Veterinary Record, 172(4), 98 LP-98.

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