WOAH rules for official confirmation of BSE in bovines
Introduction
The World Organisation of Animal Health (WOAH) Manual (12th Edition 2023), Chapter 3.4.5. on Bovine Spongiform Encephalopathy (BSE) describes how cases of BSE should be detected and confirmed.
Confirmation should always be carried out in a National Reference Laboratory (NRL).
Test methods available and purposes
Table: Test methods available for the diagnosis of BSE and their purpose.
Purpose⇒ ⇓ Method | Contribute to eradication policies | Confirmation of clinical cases | Prevalence of infection – surveillance |
Immunohisto-chemistry | Recommended but has limitations | Recommended for this purpose | Recommended but has limitations |
Western immunoblot | Recommended but has limitations | Recommended for this purpose | Recommended but has limitations |
Rapid screening tests | Recommended for this purpose | Suitable in very limited circumstances | Recommended for this purpose |
Key: ‘–’ means the method is not appropriate for this purpose.
Whether BSE-infected animals are to be identified by passive or active surveillance, it is good practice to detect and confirm disease by a combination of at least 2 test methods. So, whether the primary test is one of the confirmatory methods (i.e. immunohistochemistry or western immunoblot), or a rapid test, it is important to apply a secondary test to confirm a positive or inconclusive result by the primary test. This is not necessary if the primary test is negative. Where there is a conflict between primary and secondary test results, samples should be submitted to a WOAH reference laboratory for resolution.
For further advice on suitable primary and secondary test combinations please contact: TSE.GlobalNet@apha.gov.uk