# Commission Delegated Regulation (EU) 2020/689 of 17 December 2019 supplementing Regulation (EU) 2016/429 of the European Parliament and of the Council as regards rules for surveillance, eradication programmes, and disease-free status for certain listed and emerging diseases (Text with EEA relevance), Division 3: When a suspicion of infection with Bonamia exitiosa is required to be confirmed or ruled out in accordance with Article 58, the following visit, sampling and testing procedure must be complied with:

Extent: E+W+S+N.I.

(a) the investigation must include at least one sampling of 30 molluscs of susceptible species if the suspicion is based on a mortality report, or if not, 150 molluscs of susceptible species after the beginning of the transmission period of Bonamia exitiosa. When the transmission period is not known, the sampling shall be carried out twice a year, in spring and autumn;
(b) the samples must be tested using the diagnostic methods set out in point (i) following the detailed diagnostic methods and procedures which have been approved by the EURL for Mollusc Diseases:
(i) the presence of Bonamia exitiosa must be considered as confirmed when a positive result by histopathology, tissue imprints or in situ hybridisation is combined with a positive result by PCR followed by sequencing. If biological material is not available for histopathology, tissue imprints or in situ hybridisation, the presence of Bonamia exitiosa must be considered as confirmed when positive results are obtained using two PCR assays targeting different fragments of the parasite genome and completed by sequencing;
(ii) the suspicion of the presence of infection with Bonamia exitiosa must be ruled out, if those tests reveal no further evidence of the presence of Bonamia exitiosa.

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Source: https://www.legislation.gov.uk/eur/2020/689/annex/VI/chapter/4/section/5/division/3 (the official version)
Page: https://openlegislation.uk/eu-regulation-2020-689/annex-VI/chapter-4/section-5/division-3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.