Policy paper

Principles that apply to calculate the current routine herd testing frequency in England

Published 16 December 2020

Applies to England

1. Routine surveillance TB testing intervals are based on the regional level of bovine TB risk.

2. Default routine surveillance testing frequencies are generally applied to whole counties, except in the Edge Area counties of Derbyshire, Hampshire and Berkshire where there is annual and six-monthly testing in different parts of the counties. Parishes are only used to ensure tests are evenly distributed throughout the four years of the TB testing cycle in the Low Risk Area (refer to ‘temporal smoothing’ below).

3. The following whole counties in the South West and West Midlands of England represent the High Risk Area (HRA): Cornwall, Devon, Somerset, Dorset, Avon, Gloucestershire, Wiltshire, Worcestershire, Herefordshire, West Midlands, Staffordshire, and Shropshire.

4. Default six-monthly surveillance testing applies to cattle herds in the HRA of England.

5. Cattle herds can qualify for annual surveillance testing if they meet either of the following criteria:

• the herd has been in existence for at least six years and has not had a TB breakdown in that six year period (including breakdowns where no lesion and/or PCR/culture positive animals were disclosed). A single break from keeping cattle of less than four months during the six year period is permitted

• the herd is registered to a bovine TB health scheme licensed by CHECS and accredited at level 1 or above (CHECS bTB entry level membership does not qualify)

6. Counties which are at risk of geographic spread of bovine TB in the short to medium term are placed on annual or six-monthly surveillance testing and constitute the Edge Area of England:

• six-monthly testing in the whole of Cheshire, Oxfordshire, Warwickshire and parts[1] of Derbyshire (West), Berkshire (West) and Hampshire (North West). Some cattle herds in these parts of the Edge Area are eligible for annual surveillance testing if they meet either criterion specified in paragraph 5 above
• annual testing in all other parts of the Edge Area (i.e. Nottinghamshire, Northamptonshire, Leicestershire, Buckinghamshire, East Sussex and remaining parts[1] of Derbyshire, Berkshire and Hampshire) supplemented with radial testing around lesion and/or PCR/culture positive TB breakdowns. Radial testing consists of an immediate herd test followed by another herd test six months later. If these radial tests are completed with negative results, the herd goes back to its default annual testing frequency

7. Cattle herds in the rest of the North and East of England (referred to as the Low Risk Area (LRA)), where the incidence and risk of TB has historically been very low and there is no evidence of a wildlife reservoir of TB, are subject to four-yearly routine testing. The LRA covers the counties of Bedfordshire, Cambridgeshire, Cleveland, County Durham, Cumbria, Essex, Greater London, Greater Manchester, Hertfordshire, Humberside, Isle of Wight, Isles of Scilly, Kent, Lancashire, Lincolnshire, Merseyside, Norfolk, Northumberland, North, South and West Yorkshire, Suffolk, Surrey, Tyne and Wear and West Sussex.

8. Defra has demonstrated that the majority of lesion and/or PCR/culture positive TB breakdowns in four-yearly testing areas can be attributed directly to movements of undetected infected cattle from the endemic TB areas in England and Wales without further consequences for other cattle herds in the locality.

9. However, any individual herds in the LRA that are considered to be at a higher risk of acquiring or spreading TB infection (because of management practices or recent disease history) are placed on annual or more frequent testing. This includes:

• herds at risk because of management practices, for example: bull hirers, producer retailers of raw milk, city or open farms, herds with high-risk trading practices
• breakdown herds, or herds that have regained Officially Tuberculosis Free (OTF) status but still require a post-breakdown testing regime
• herds that fall within (or straddle) a 3km radius around a lesion and/or PCR/culture positive TB breakdown, or are considered to be epidemiologically relevant to that breakdown
• in response to changes in the local disease situation e.g. herds in a TB hotspot placed on six-monthly testing

10. To optimise the effectiveness of TB surveillance in the LRA, the routine four-yearly testing of herds is organised so that an equal proportion of herds in a parish are tested every year of the four-year cycle. This ‘temporal smoothing’ ensures that routine herd tests are distributed equally across the parish over time, thus increasing the probability of detecting infection in the area as early as possible.

11. Mandatory interferon gamma blood testing applies in all new lesion and/or PCR culture positive TB breakdowns in the LRA and annual surveillance testing parts of the Edge Areas. In the HRA this test is applied more selectively in certain herds with lesion and/or PCR/culture-positive breakdowns that satisfy certain criteria. For more information refer to interferon-gamma blood testing of cattle.

12. All keepers of cattle herds on annual or more frequent testing must also comply with statutory pre-movement testing requirements, unless an exemption applies to the animal being moved or the type of movement. This includes herds in the LRA that are tested more frequently than the default four-yearly interval as in paragraph 9 above.

13. Compulsory post-movement testing applies to cattle entering the LRA of England from annual or more frequent TB testing areas of GB unless a specific exemption applies. From 1 August 2023, compulsory post-movement testing will apply to cattle moved to annual surveillance testing parts of the Edge Area from the HRA, six-monthly surveillance testing parts of the Edge Area and from Wales The aim of the post-movement testing policy is to further reduce the risk of introducing TB infected cattle into lower incidence areas of England.

14. For the whole of England, forward and backward tracing tests are required for animals from lesion and/or PCR/culture-positive TB breakdowns.

TB Programme Defra
May 2023

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[1] The list of parishes on six-monthly and annual testing in the counties of Derbyshire, Berkshire and Hampshire can be found on the Bovine TB testing intervals page on GOV.UK