Quality assurance of tuberculin skin testing in Great Britain - Veterinary Practice
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Quality assurance of tuberculin skin testing in Great Britain

The cornerstone of tuberculosis (TB) control in cattle and other species is the accurate detection and removal of animals infected with Mycobacterium bovis. The single intradermal comparative cervical tuberculin test (SICCT) is the internationally accepted standard and primary screening test for TB in cattle in Great Britain (GB).

Surveillance TB testing of cattle herds is the foundation of the bovine TB eradication programmes in England and Wales, and integral to maintaining Scotland’s officially TB free (OTF) status. It is vital that the SICCT test is performed carefully and accurately to identify TB-infected cattle and remove them rapidly before they can transmit the disease to other cattle and wildlife. In England and Wales, statutory TB skin testing is carried out by delivery partner Official Veterinarians (OV) and a small number of independent OV practices. In Scotland the work is delivered through OV practices.

Quality assurance programme

Quality assurance of bovine TB controls is essential for a successful eradication programme and is also required to give confidence to export partners. An enhanced field audit programme of TB skin testing conducted by OVs was introduced in 2013 and aims to:

  • provide transparent TB skin-testing procedures and standards
  • encourage good health and safety practice for undertaking TB skin tests
  • maximise the probability of accurate detection of TB-infected animals
  • improve working relationships between APHA, delivery partners, OV practices and TB testers
  • support shared responsibility for setting and improving TB testing standards
  • assist with meeting third party and international requirements for assurance of TB skin testing to enable trade

In England and Wales, the delivery partners are responsible for ensuring that TB skin testing is carried out to a high standard. The delivery partners have their own quality management systems which incorporate a random selection of OVs for field audits on a rolling basis to quality assure delivery of TB skin testing. In Scotland, quality assurance is the responsibility of the OV practices. In England only, since 2 November 2020, para-professional Approved Tuberculin Testers (ATTs) can carry out TB skin testing of cattle (excluding pre-export tests) and are subject to the same quality assurance programme as OVs. The Animal & Plant Health Agency (APHA)’s contracted training provider carries out audits for the non-delivery partner OVs and ATTs. Regular revalidation is mandatory for OVs undertaking TB skin testing in GB, and for ATTs in England.

As the competent authority, APHA is responsible for auditing the delivery partners in England and Wales, and OV practices in Scotland, to quality assure delivery of TB skin testing across GB. APHA also carries out risk-based unannounced audits of TB testers across GB to check that TB skin testing is being carried out correctly in line with agreed standard operating procedures (SOPs). An SOP for conducting the SICCT test is published in the instructions for OVs and ATTs on the APHA Vet Gateway. All field audits, whether conducted by the delivery partners or APHA, are carried out in accordance with the published Tuberculin Skin Test Audit – Minimum Requirements (TR586).

Individual TB testers are routinely selected for audit on a rolling programme, and on the basis of intelligence and/or data that raises potential concerns about their TB-testing performance. Both routine and targeted audits will continue as part of the existing field audit programme.

Where non-compliance with the TB skin testing SOP is found at field audits, appropriate corrective action is taken depending on the nature and severity of the non-compliance(s). This is assessed on a case-by-case basis, taking into account possible rectification in situ and/or mitigating factors. Possible actions taken are described in part 2 of the published Tuberculin Skin Test Audit – Minimum Requirements (TR586).

Information regarding any non-compliance is shared with the relevant OV practice and delivery partner. All cases are passed to APHA for review with the responsible OV practice and delivery partner in England and Wales. APHA assesses any sanctions proposed and provides advice regarding future conduct.

APHA pilot

To further enhance the existing field audit programme of TB skin testing, APHA is conducting a six-month pilot in England and Wales to assess use of data to better inform selection of individual TB testers for further investigation.

The flow chart below describes the process of selection and investigation of outliers by APHA.

The APHA pilot will run from 1 June 2021 for six months after which APHA will review the outcome and communicate this to delivery partners and OV practices. The results of the pilot will be used to inform and enhance quality assurance of TB skin testing in GB.

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