Edge areas of England

These TB cattle control enhancements were introduced by Defra from January 2018 following a public consultation in August 2016.

Background

The Edge Area was established in January 2013 as part of the government’s Strategy for achieving Officially Bovine Tuberculosis Free (OTF) status for England by 2038.

For the purposes of bovine TB control, England is split into three different management regions:

  • High Risk Area (HRA) relatively high levels of bovine TB when compared with the Edge Area and LRA.  There are proportionally more repeat cases among herds and there is a recognised reservoir of infection in wildlife (badgers)
  • Low Risk Area (LRA) – very low levels of bovine TB and no recognised significant reservoir of the disease in wildlife. Most, if not all TB breakdowns are the result of undetected infection brought in through cattle movements. The government has applied for OTF status for the LRA of England
  • Edge Area – the buffer zone between the HRA and LRA which contains local disease fronts advancing eastwards from the HRA towards the LRA. The level of bovine TB in the majority of the Edge Area is much lower than in the HRA, but higher than in the LRA

The level of bovine TB varies between regions and that is why different control measures are applied in different parts of the country. Cattle herds in the Edge Area are subject to enhanced disease control measures to try to halt the spread of disease from the HRA, with the longer term aim of achieving OTF status for counties in the Edge Area.

Why are additional cattle controls required in the Edge Area?

Despite Defra implementing enhanced cattle controls in the Edge Area from 2013, the overall level of bovine TB is still increasing. In all Edge Area counties, infection is being introduced into herds as a result of purchase of undisclosed infected cattle, usually from the HRA but also from other parts of the Edge Area1.  Exposure to infected badgers or contamination from them is also believed to play a role in several counties.  For more information about bovine TB in the Edge Area counties and part counties, visit GOV.UK to access the Edge Area Summary Descriptive Epidemiology Reports.

In most Edge Area counties there is evidence that infected herds are being discovered sooner after infection is introduced than in the past, indicating some success in control measures1. However, it is essential that cattle measures are strengthened to reverse the trend of rising levels of bovine TB, and halt the spread of disease.

Edge Area changes

The following changes were implemented from January 2018.

1. Re-classification of Edge Area counties

The following part Edge, part HRA split counties were re-classified as fully in the Edge Area:

  • Cheshire
  • Derbyshire
  • East Sussex
  • Oxfordshire
  • Warwickshire

The previous HRA parts of split counties were incorporated fully into the Edge Area. Herds in these counties are subject to mandatory interferon gamma blood testing in TB breakdowns with lesion and/or culture positive animals.

Eligibility for support from the Badger Edge Vaccination Scheme also applies.

2. Cattle testing arrangements in the Edge Area

Herds in some parts of the Edge Area are subject to six-monthly routine surveillance testing, while others remain on annual testing supplemented with 3km radial testing around TB breakdown herds with lesion and/or culture positive animals.

The table below shows the previous surveillance testing regime and current testing regime for each Edge Area county.

County Previous boundaries Previous testing regime(s) Changes to boundaries and current surveillance testing regime
Berkshire Fully Edge Annual Berkshire West is on six monthly testing
All other areas in Berkshire are on annual with radial testing
Buckinghamshire Fully Edge Annual Annual with radial testing
Cheshire Part Edge & part HRA Cheshire South (HRA) Annual Fully Edge and six monthly testing
Cheshire North (Edge) six monthly testing NO CHANGE in testing regime
Derbyshire Part Edge & part HRA Derbyshire West (HRA) Annual Fully Edge and six monthly testing
Derbyshire (Edge) Annual with radial testing NO CHANGE in testing regime
East Sussex Part Edge & part HRA Annual Fully Edge – Annual with radial testing
Hampshire Fully Edge Annual Hampshire North West is on six monthly testing
All other areas are on annual with radial testing
Leicestershire, Northamptonshire and Nottinghamshire Fully Edge Annual Annual with radial testing
Oxfordshire and Warwickshire Part Edge & part HRA Annual Fully Edge on six monthly testing

In summary, these changes amount to:

  • Routine six-monthly herd testing in Warwickshire, Oxfordshire, Cheshire, the west of Berkshire, northwest Hampshire and west Derbyshire – i.e. where the level of disease is highest and where radial testing may be impractical or administratively complex
  • Radial testing around TB breakdowns with lesion and/or culture positive animals in all other parts of the Edge Area, as currently happens in the LRA

Different testing regimes in parts of Berkshire, Derbyshire and Hampshire reflect differences in the level of disease across these counties. For a list of parishes subject to six-monthly testing in these counties see the TB information note.

How will these changes help control bovine TB in the Edge Area?

Incorporating the previous HRA parts of split counties fully into the Edge Area means that herds in these counties with higher levels of bovine TB are subject to the enhanced surveillance testing regime. Additionally, mandatory interferon-gamma blood testing applies to new TB breakdown herds with lesion and/or culture positive animals in the Edge Area.

Six monthly testing in Edge Area counties with higher levels of bovine TB aims to identify infected herds earlier and reduce the risk of TB spreading. Routine six monthly testing has proved useful in finding disease earlier in the Cheshire Edge Area, and greater certainty around TB testing dates means it is easier for cattle keepers to plan and manage their resources throughout the year.  Six monthly testing also means that keepers have a second Defra-funded test each year that could be used as a pre-movement test for cattle that they wish to sell or move to another holding.

Annual testing in Edge Area counties with lower levels of bovine TB is supplemented with radial testing to check for spread to neighbouring cattle herds within a 3km radius of TB breakdown herds with lesion and/or culture positive animals.

The enhanced surveillance and control measures in the Edge Area will protect other cattle herds and reduce the risk of establishment of new infection in badgers.

Q&A

General

What has changed?

The previously part Edge, part HRA split counties of Cheshire, Derbyshire, East Sussex, Oxfordshire and Warwickshire were re-classified as fully in the Edge Area.  TB breakdown herds with lesion and/or culture positive animals in these counties are now subject to mandatory interferon-gamma blood testing.

Additionally, herds in some parts of the Edge Area are subject to six-monthly routine surveillance testing, while others remain on annual testing supplemented with 3km radial testing around TB breakdown herds with lesion and/or culture positive animals.

Please refer to the table above and the TB information note for more details on the surveillance testing regimes.

Why were these Edge Area changes introduced?

There is an overall trend of rising levels of bovine TB in the Edge Area despite enhanced surveillance testing and cattle controls introduced in 2013.  This trend needs to be reversed so that there remains a good prospect of Edge Area counties obtaining OTF status as soon as possible as part of the government’s Strategy for eventually obtaining OTF status for the whole of England.

If the disease is endemic in wildlife in the Edge Area and is not being controlled, why has Defra introduced more cattle measures?

Although wildlife involvement is suspected in some parts of the Edge Area, there is no evidence that bovine TB is endemic in wildlife in all of the Edge Area counties. The Edge Area Badger Survey of road kill badgers carried out by the University of Surrey and the University of Nottingham will provide further information about levels of TB infection in badgers.

Licensed badger culling has been carried out in the Edge Area from 2017 in areas where the predominant source of infection for TB breakdown herds is infected badgers. Natural England will consider new applications for licensed badger culling in Edge Area counties. Additionally, all Edge Area counties are eligible to apply for the Badger Edge Vaccination Scheme.

In 2016, purchase of undisclosed infected cattle was the main source of infection for TB breakdown herds in four of the Edge Area counties, and an important source for all other counties except Derbyshire1.  Cattle controls have been demonstrated to detect infection earlier and reduce spread of disease, which is why they are being enhanced further in the Edge Area.  In addition, cattle keepers are encouraged to protect their herds by improving on-farm biosecurity and considering TB risk when purchasing animals.

Why are there split testing regimes in some Edge Area counties?

The levels of bovine TB vary considerably across some Edge Area counties.  Therefore different surveillance testing regimes and cattle control measures are needed to strike a balance between robust disease control and too much testing of cattle herds.

Who pays for the six monthly and radial tests?

These are government funded TB tests.

What routine testing is required in Approved Finishing Units in the Edge Area? Were these units affected by the changes?

Approved Finishing Units (AFU) are high biosecurity units and provide an outlet for rearing/finishing of clear tested cattle from TB restricted holdings without such facilities. Only AFUs without grazing are permitted in the Edge Area and the default position is that no routine surveillance testing is required in these units.  However, APHA retain the option to test in exceptional circumstances, for example if there is extensive evidence of TB found at slaughter.  Further information on AFUs is available on the TB Hub and GOV.UK

Will my herd be eligible for interferon gamma blood testing?

The interferon gamma blood test supplements the tuberculin skin test to maximise the probability of detecting infected animals in TB breakdown herds.  Gamma testing is a mandatory test for all TB breakdown herds located in the Edge Area which have animals that are lesion and/or culture positive.  For more information about the gamma test see the detailed guidance on the TB Hub.

Will holdings in the Edge Area be subject to six monthly testing or radial testing requirements forever?

No. Defra is developing criteria which will determine when switches from radial to six monthly testing (and vice versa) in Edge Area counties should be triggered.  We hope that improvements in the disease situation in counties (or part counties) subject to six monthly testing will allow these counties to eventually revert to annual testing.

Six monthly testing

What is the testing window for a six monthly test?

60 days, the same window as a routine whole herd test.

How do I know if my herd requires six monthly surveillance testing?

Please see the table above which outlines the previous testing regime in Edge Area counties, and the current testing regime. If your herd is located in one of the split counties (Berkshire, Derbyshire and Hampshire) then please see the TB information note for a list of parishes that are subject to six monthly surveillance testing. APHA will advise you in writing if your herd will be subject to six monthly testing.  

Can my six monthly surveillance test count as a pre-movement test?

Yes.

Radial testing

What is a radial test?

It is a TB surveillance test around all new TB breakdowns with lesion and/or culture positive animals.  The purpose of the test is to check neighbouring cattle herds for spread and to help identify any undetected source of infection in the locality.  All cattle holdings falling within, or straddling, a 3km radius circle from the new TB breakdown will be identified and required to undertake an immediate radial test of all the cattle on the holding aged 42 days or older.  Herds are not placed under TB restrictions whilst awaiting radial testing.

How will I know if my herd needs a radial test?

Cattle keepers receive a test notification letter from APHA informing them that their herd requires an immediate radial test, specifying the date by which the test is due.

What is the testing window for a radial test?

60 days. The window for a radial test usually starts immediately on receipt of the notification from APHA unless a clear herd test has been completed within the previous two months.  In such cases, the radial test would be deferred until six months from the date of the last herd test.

When will the next test be due after the immediate radial test?

Providing the immediate radial test (RAD) is completed with negative results, the herd will require a further radial test (RAD6) six months after the immediate test was carried out.  Thereafter the herd will revert to routine annual surveillance testing.

Can a radial test count as a pre-movement test?

Yes.

For more information about radial testing in the Edge Area, see the TB hub.

 

Testing for holdings spanning areas undergoing different testing regimes

What testing regime applies to a herd if it is grazing on land which spans areas undergoing different testing regimes e.g. grazing an area subject to annual testing supplemented with radial testing but their permanent CPH is in a six monthly testing area?

The six monthly testing regime applies, as the default testing regime across a border is for the more rigorous regime to apply.

What testing regime applies to a herd if it is grazing in an area subject to six monthly testing but their permanent CPH is in an annual testing (with radial) area?

Again, the six monthly testing regime applies, as the default testing regime across a border is for the more rigorous regime to apply. 

If a TB breakdown occurs in a six monthly testing area but is within 3km of holdings in a radial testing area, are those holdings subject to radial testing?

No. Radial testing is only carried out on holdings in the radial testing area.  However, contiguous testing (CON) may be required if deemed necessary, at case vet discretion e.g. where a new TB breakdown poses a very high risk to neighbouring herds, particularly where the breakdown is close to the boundary of a different testing regime.

Reference

  1. Bovine Tuberculosis in England in 2016 Edge area summary descriptive epidemiology report