Division II.3 Official investigation and diagnostic methods to rule out or to confirm the presence of ISA

When a suspicion of ISA shall be confirmed or ruled out in accordance with F1Part 4 of the Aquatic Animal Health Regulations, the following inspection, sampling and testing procedure shall be complied with:

1. (a)

   the official investigation which shall include at least one health inspection and one sampling of 10 moribund fish, when clinical signs or post-mortem signs consistent with ISA are observed. If no clinical signs or post-mortem signs consistent with ISA are observed, the health inspection shall be followed by targeted sampling of minimum 30 moribund fish or fresh post-mortems with normal constitution in accordance with point I.1. Samples shall be tested in accordance with the diagnostic methods set out in point (b);

2. (b)

   in the case of a positive result of RT-qPCR for HPR-deleted ISAV, further samples shall be tested before the implementation of the initial control measures provided in F2Part 4 of the Aquatic Animal Health Regulations. A suspected case of infection with ISA shall be confirmed in accordance with the following criteria using the detailed methods and procedures set out in Part 3 of Annex II:

   1. (i)

      Detection of ISAV by RT-qPCR, including sequencing of the HE-gene to verify HPR-deletion, and detection of ISAV in tissue preparations by means of specific antibodies against ISAV (namely IHC on fixed sections or IFAT on tissue imprints)

      or

   2. (ii)

      detection of ISAV by RT-qPCR, including sequencing of the HE-gene to verify HPR-deletion, and

      isolation and identification of ISAV in cell culture from at least one sample from any fish from the farm;

3. (c)

   where the presence of clinical, gross pathological changes or histopathological findings consistent with ISA are observed, the findings must be corroborated by virus detection by two diagnostic methods with independent principles of detection, such as RT-qPCR and IHC, in accordance with Part 3 of Annex II.

   The suspicion of ISA may be ruled out, if tests and inspections over a period of 12 months from the date of the suspicion are found to reveal no further evidence of the presence of ISA.