Guidance

Testing for TB in your herd: what this means to you (Wales)

Updated 14 February 2024

Section 1: Why we test

Bovine TB

Bovine tuberculosis (TB) is a chronic, infectious disease of bovine animals (cattle, buffalo and bison) that mainly affects the respiratory system. It is caused by the bacterium Mycobacterium bovis (M. bovis), which can also infect and cause TB in badgers, deer, goats, pigs and many other mammals, including people.

Bovine TB can spread to cattle in a number of ways, including contact with:

• an infected domestic animal (usually other cattle)
• infected wild animals (including badgers)
• contaminated equipment, feedstuffs, slurry

The risks to people from bovine TB

While people can be infected with M.bovis, most cases of TB in humans in Great Britain arise from infection with the human tubercle bacillus (M. tuberculosis). This bacillus is closely related to M. bovis but it is transmitted through close contact between people rather than from cattle. The risk of people contracting bovine TB from cattle in Great Britain is currently considered very low, but cases have been recorded in the last few years. The risk is increased where unpasteurised milk or milk products are consumed.

Get further information on managing the public health consequences of bovine TB.

Testing cattle for bovine TB

The Welsh Government has testing programmes in place for:

• surveillance (screening cattle for the presence of infection)
• breakdown management, (where a herd is known to have infection present) and
• where there is suspicion of infection

These testing programmes determine the TB status of the herd and facilitate trade in cattle and products, both domestic and international. Testing is carried out to:

• protect public health
• identify TB infected cattle and prevent it spreading and
• make sure that cattle do not suffer because of TB

Anyone who keeps cattle is required by law to have their cattle tested for bovine TB. Cattle are tested at an interval that is appropriate to both the incidence of TB infection in the area the herd is located in and the risk that the herd presents, which is related to the type of enterprise. All cattle herds in Wales are currently tested at least once a year. Herds in the Intensive Action Area in West Wales are tested at least twice a year. See the Welsh Government Bovine TB: intensive action area map for details.

Effective surveillance is essential to identify TB infection early. This is necessary so that steps can be taken to stamp out disease in the infected herd, reduce the spread of disease and to facilitate trade with other countries.

Surveillance does not rely on testing alone. There are also requirements for:

• reporting of suspicious clinical cases
• reporting of suspicious lesions at routine inspection in the slaughterhouse and at private post-mortem examinations

Reports will result in investigation, restrictions where necessary and additional testing.

Once infection has been identified in a herd, testing is then increased, in order to identify other infected animals within the herd and to return the herd to TB free status as quickly and effectively as possible. This will reduce the opportunity for further spread of the disease both within and around a herd.

Additional testing is carried out where there is suspicion of infection, either in an individual animal or a herd due to:

• a report from the slaughterhouse of lesions that are suspected to be due to infection with M bovis
• an animal that has been identified as moving from a farm on which TB is present
• infection in another herd which may have spread to animals in your herd, either due to location or due to management, such as sharing equipment

A report from the slaughterhouse

Sometimes lesions suggestive of TB are found in animals at routine slaughter inspection. These are known as slaughterhouse cases. If such lesions are found, your herd will be placed under movement restrictions pending further investigation and your local APHA office will discuss your testing requirements with you.

Inconclusive Reactors (IRs)

Finding only Inconclusive Reactors (IRs), with no reactors in your annual herd or other surveillance test may be an early indication that you have infection in your herd. Your herd will be restricted and the IRs must be isolated. They will be subjected to further tests and if all are clear herd restrictions can be lifted.

APHA will send you a letter explaining the restrictions and the testing necessary.

Pre- and post-movement testing

Cattle moving from all herds in Wales must be skin tested with negative results within 60 days prior to the movement. This is to reduce the risk of spreading TB from one herd to another.

Cattle must be post-movement tested between 60 and 120 days after their arrival to the low TB area of Wales, if they come from:

• other areas of Wales
• the high risk areas of England
• the edge areas of England
• Northern Ireland

Cattle must also be post-movement tested between 60 and 120 days after their arrival to the intermediate TB areas of Wales if they come from:

• the high TB areas of Wales
• the high risk area of England
• Northern Ireland

This is to reduce the risk of spreading TB from areas of higher TB incidence to the low and intermediate TB areas.

Get information on pre- and post-movement testing in Great Britain and the bovine TB eradication programme.

Requirement to test

APHA will send you a notice to tell you when your herd or a specific animal requires testing and you must arrange a bovine TB test before the date that this test is due. Your herd will be placed under movement restrictions (TB2) immediately if testing becomes overdue as the TB status of your herd will be unknown. The restrictions prevent movements of cattle on or off your premises and will remain in force until your testing has been completed and there is no evidence of TB. Where testing is overdue, licences authorising low risk moves will not be issued (zero tolerance).

The compensation payable for any reactors identified in tests which are overdue may be reduced.

APHA do not send notices for pre- and post-movement tests. You need to arrange and pay for these yourself when required.

The TB status of your herd

Herds giving negative results at routine surveillance testing are classed as Officially TB Free (OTF).

In all cases where animals are removed from your herd following a skin test finding of reactors (or inconclusive reactors at consecutive tests), the OTF status of your herd will be withdrawn (OTFW). There are scenarios listed below, where the status will be suspended, but in these cases if lesions typical of bovine TB are found at post-mortem examination, or the Mycobacterium bovis (M.bovis) organism is identified by the PCR (polymerase chain reaction) test (or culture, in the absence of PCR), or reactors are found on further skin testing, then the status will be withdrawn. This is important as it means your herd will require additional testing before restrictions can be lifted.

Suspension: Officially TB Free status Suspended (OTFS)

The OTF status of your herd will be suspended when either:

• a tuberculin skin test is completed and inconclusive reactors are identified with no skin test reactors
• suspect lesions of TB are detected in animals at routine slaughter inspection
• clinical signs of TB are detected in animals
• the TB status of the herd is unknown because a routine tuberculin skin test is overdue

In all cases, your herd will be placed under movement restrictions (TB2) and further testing done.

Withdrawal: Officially TB Free status Withdrawn (OTFW)

The OTF status of your herd will be withdrawn when:

• a tuberculin skin test is completed with positive results in one or more animals
• an animal with an IR result is an IR at the retest
• lesions typical of TB are found at the post mortem examination of tuberculin skin or TB blood test reactors or IRs
• resolved inconclusive reactors illegally moved from England to Wales test positive to TB blood test
• M. bovis is identified by PCR, or culture, from tissue samples from any animal in the herd
• a gamma interferon blood test is completed on an inconclusive reactor in your herd with positive results
• your herd’s status is suspended for one of the reasons listed in the OTFS section above and is considered high risk

Your herd will be placed under movement restrictions (TB2) and further testing done.

Enforcement of TB policy

When your herd is put under movement restrictions either as a result of suspicion or confirmation of TB or as a result of a TB test being overdue, APHA informs your local authority and sends them copies of the notice.

Any non-compliance with the conditions of notices, pre-movement testing, post-movement testing, licences or TB testing requirements is a breach of the legislation and the local authority or Welsh Government may consider taking appropriate enforcement action.

If the Welsh Ministers decide that there has been a breach of the TB Order, the way in which compensation is calculated for reactors and cattle slaughtered for TB control purposes will be affected for a period of six months following the breach.

Enforcement action by the Animal and Plant Health Agency (APHA)

If an APHA vet thinks that a cattle keeper should do something or stop doing something for the purpose of preventing the spread of bovine TB, they may serve a Veterinary Requirements Notice (VRN) or a Biosecurity Requirements Notice (BRN) on the keeper.

Enforcement action by your local authority

Your local authority will follow its enforcement policy and take action as appropriate. This ranges from verbal advice and written warnings to prosecution.

Offences are covered under the Animal Health Act 1981 and penalties include the following:

• compulsory TB testing at the expense of the owner
• written warning
• fine not exceeding £5,000 per offence
• a custodial sentence

A failure to comply with the TB legislation may also be considered an intentional breach of cross compliance and could result in a reduction in payment on a number of schemes, including the Basic Payment Scheme (BPS) for your farm.

Read more about the Basic Payment Scheme on the Welsh Government website.

Section 2: How we carry out the TB test

The Single Intradermal Comparative Cervical Tuberculin (SICCT) test, commonly known as the tuberculin skin test, is the primary bovine TB test used throughout Europe.

The gamma interferon TB blood test is used alongside the skin test in certain circumstances to help identify animals at an earlier stage of infection. Since May 2018, the IDEXX Antibody blood test has also been increasingly used, mainly in herds with longer duration TB breakdowns.

The tuberculin skin test

The tuberculin skin test is the internationally accepted standard for detection of infection with M. bovis. It is considered the best test currently available.

It is designed to test the animal’s immune response and involves injecting a small amount of tuberculin (a harmless protein extract of M. bovis) into the skin of the animal. In most cattle infected with M. bovis, this will cause the animal’s immune system to react to the tuberculin and result in a localised allergic reaction (swelling) of the skin a few days after the injection.

Cattle are sometimes infected with other types of mycobacteria which may also cause the animal to react to the test. To distinguish between animals infected with M. bovis and those infected by other mycobacteria, each animal is also injected with an extract from the organism that can cause TB in birds (avian TB) at the same time.

The test is read 72 hours after the injections have been carried out. The size and nature of the reaction to both types of tuberculin (‘avian’ and ‘bovine’) are compared to determine whether the test result is considered positive, negative or inconclusive.

The person carrying out your test will be an approved tester trained to carry out the tuberculin skin test. This will either be a vet or an Approved Tuberculin Tester (ATT) from your nominated veterinary practice, an APHA vet or an APHA Animal Health Officer.

Preparation for the test

APHA will send you a test notification letter giving details of the test that is required.

You are required by law to provide appropriate facilities and assistance to enable the tester to carry out the test.

A properly planned test, using well designed and constructed handling facilities, will avoid unnecessary stress for you and your cattle, save time and, most importantly, be safer for all involved.

If you have any questions about the test, please contact APHA Wales or your vet for advice.

What animals to test

The test notification letter from APHA will specify which animals need testing. You must ensure that all eligible animals are presented for testing.

Identification

Ensure your cattle are correctly identified. This is a legal requirement but will also make it easier and quicker to identify individuals and record skin measurements or blood samples against the correct animal.

Gathering

To avoid delays, your cattle should be gathered in readiness for the test. If it is not possible to test all your eligible cattle on a single day, you must be able to keep them in the same, separate groups until all cattle have been tested.

Records

You should make sure that the record of the cattle present in your herd is correct and up-to-date on the Cattle Tracing System (CTS) run by the British Cattle Movement Service (BCMS). This record is often used by the tester to download a list of the cattle that are eligible for testing and all animals on this list must be accounted for.

You may be asked to provide your herd register/cattle movement records and veterinary medicines records, so please have these available for inspection.

Veterinary treatment and other tasks

While you have the cattle gathered you may wish to undertake other management tasks but these should not interfere with the test. Routine veterinary medicines, such as wormers or vaccines, should only be given to animals once they have tested clear.

Previously tested animals

Animals that have recently moved onto your premises may have been skin tested for TB in the previous 60 days. If you can provide evidence of this test you will need to notify the person doing the test and these animals will not be tested. If you are unable to provide evidence, they will need to be tested at a date that is at least 60 days after the movement on to your herd. If in doubt, ask your vet.

Facilities

Handling facilities will be needed for both days of the test to allow safe movement of, access to and good restraint of the animal being tested. The tester must have safe and well-lit access to:

• read and record the animal’s identification tag
• clip the test areas on the neck
• measure the skin thickness of the clipped areas and
• inject the tuberculin

You will need to provide suitable handling facilities for the cattle to be tested, such as a crush and penning system, ideally linked by a securely constructed race.

The facilities should be in good working order and appropriate for the size and breed of cattle to be tested, for example specially adapted if handling Highland or Longhorn cattle. If you do not own a crush or penning system, you should arrange to borrow or hire one. To make sure you do not compromise the biosecurity of your herd, or anyone else’s, all equipment should be cleansed and disinfected before and after use.

Get advice on suitable handling, restraint and housing of cattle on the Health and Safety Executive website.

Assistance

By providing sufficient and appropriately experienced help to move groups of cattle into and through the handling facilities, the test will go more quickly with less stress to your animals and less risk of injury to all involved. APHA staff will not routinely be able to help gather or move animals.

If you fail to present your cattle for testing safely and the tester considers the facilities and assistance provided to be inadequate, the test will not proceed until the issues are resolved. This could mean your test will become overdue and, if this is the case, movement restrictions will be applied.

Procedures for the test

For each test:

• the animal is identified (by its official ear tag) and its identification recorded
• the hair is clipped to mark two injection sites in the middle of the side of the neck, one above the other
• the thickness of a fold of skin at each site is measured with callipers and recorded in mm
• tuberculin is injected into the skin; avian tuberculin into the upper site, bovine tuberculin in the lower site
• after 72 hours, the tester returns, re-checks each animal’s identity, palpates the skin at the injection sites and re-measures and records any reactions, and records the results of the test against each animal
• cattle that have been injected with tuberculin are not permitted to move off the holding until the results of that test have been read 72 hours later - in exceptional cases, APHA will issue a licence to allow such moves

The gamma interferon blood test for TB

In specific circumstances, the gamma interferon test is used in combination with the skin test to help with early identification and removal of TB infected animals and reduce the risk of further spread of disease.

The tuberculin skin test is the primary test used across the world for the mass screening of cattle. The gamma interferon test is an additional approved test and is used based on veterinary advice in herds with severe breakdowns, persistent or recurrent TB problems, or in areas where TB incidence is low. Some of these tests have to be completed before the movement restrictions can be removed from the herd.

In Wales, gamma interferon tests can only be carried out by APHA. Usually it will be an Animal Health Officer who will take blood samples from your cattle.

Cattle testing positive to the gamma interferon test will be classed as reactors and will be valued and slaughtered in the same way as skin test reactors.

Cattle that have had a sample taken for a TB blood test cannot be moved off until the results of the test are received. In exceptional cases, APHA will issue a licence to allow such moves.

The IDEXX Antibody test

The IDEXX Antibody test is also now increasingly used alongside the skin test and the gamma interferon test in Wales to identify TB infected animals, particularly in herds with long duration TB breakdowns.

An animal’s immune response to infection with M.bovis, the organism responsible for bovine TB, is a very complex one and not all TB infected animals respond positively to the skin test or the gamma interferon test.

The IDEXX test aims to detect antibodies, proteins that the immune system makes to help fight infection. Before the blood sample is taken, the animal must have had a skin test 10-30 days earlier to stimulate release of these specific antibodies to M.bovis.

Cattle that have had a sample taken for a TB blood test cannot be moved off until the results of the test are received. In exceptional cases, APHA will issue a licence to allow such moves.

Further information

Read about Bovine TB on the Welsh Government website.

Contact APHA Wales for further practical advice and guidance.

Devolution of animal health and welfare power has resulted in a number of significant differences in the policies regarding bovine TB in Wales, England and Scotland. GOV.UK and the Welsh Government, Defra and Scottish Government websites provide up to date detail on these policies.

If you farm on the border of England and Wales, or England and Scotland, you should be aware that the location of your animals at the time of the test will influence which protocols are relevant to you.