He added: "For example, there is a disproportionate reaction to an identified case of West Nile Virus as to an identified case of an impaired-driving death".
The practice is not in itself illegal or unsafe, the experts said, but in the event of a problem, like an identified case of E. coli, the mixing of several days' production makes it harder for officials to know the extent of the contamination.
This secondary definition of a source population on the basis of an identified case series complicates control selection as it is then difficult to demonstrate that controls are members of the same population as cases at the time of sampling.
When an identified case had >1 type of positive influenza test, we used the test type with the highest sensitivity RT-PCR, viral culture, DFA, RIDT (ordered from highesensitivity RT-PCRtiviral—for the analysis.
If an identified case had no other test type and a positive result from an unspecified laboratory test documented in the medical chart, we assumed 100% sensitivity for that test.
However, the fact that GPs will be given the opportunity to respond to an identified case of depression following the treatment phase of the PROMISE-D trial, means that this trial will provide a stringent test of the long-term efficacy of these two interventions.
