When a decision has been made to conduct an investigation into a reported non-bacterial TTI case, it may be possible to obtain sufficient information by reviewing results of testing of subsequent donations from the involved donor(s). If this is not the case, consideration should be given as to which donors require further investigation, and whether this can be satisfactorily carried out with samples already available at the Blood Centre from the index or any subsequent donation. This decision is dependent on the premise that subsequent samples may conclusively demonstrate the development of infectious markers (e.g. antibodies) in one of the implicated donors. It is expected that Blood Establishments will retain samples from each donation for a minimum period of 3 years in a suitable frozen archive. The retrieval of samples from this archive must be fully documented and be restricted mainly to such investigations.
If further investigation is required, and suitable blood samples are not available from the donor, then the decision may be made to contact the donor(s) and request further samples.
Decisions for each case and each donor will be on an individual basis depending upon the circumstances, timing, assessed likelihood of TTI and resources required. In cases of doubt, there should be a mechanism to ensure that there is a system for review and agreement on the way forward.
In instances where there is doubt whether a donor has been the source of a TTI, specialised molecular genotyping of both implicated donor and infected recipient may be necessary to prove conclusively whether TTI did indeed occur.