Sites under
suspicion of infection were automatically issued a temporary
statutory notice prohibiting the movement of fish
on or off the site until the results of diagnostic testing
were known. These restrictions were also placed on any
water not deemed as being epidemiologically distinct from
a suspect site. Testing was conducted on susceptible fish
species (as listed by the OIE) using cell culture with confirmation
by reverse transcription polymerase chain reaction
(RT-PCR) (Stone et al., 2003), as described and validated in
accordance to the standards documented by the OIE (Office
International des Epizooties, 2009). In line with the criteria
set out under EU directive 2001/183/EC (and 92/532/EEC
prior to that), 30 samples, each comprised of pooled tissues
from five individual fish would be taken by a Cefas
Fish Health Inspector from units across the site, focussing
on moribund and diseased fish. This approach provided a
95% chance of detecting the pathogen if present in the population
at
≥10%, assuming the test method is 100% sensitive
and specific.