Current perspectives in transfusion-transmitted infectious diseases: emerging and re-emerging infections.

backgroundIn August 2009, a group from the AABB (Stramer et al., Transfusion 2009;99:1S-29S, Emerging Infectious Disease Agents and their Potential Threat to Transfusion Safety; http://www.aabb.org/resources/bct/eid/Pages/default.aspx) published a Supplement to Transfusion that reviewed emerging infectious disease (EID) agents that pose a real or theoretical threat to transfusion safety, but for which an existing effective intervention is lacking. The necessary attributes for transfusion transmission were outlined including: presence of the agent in blood during the donor's asymptomatic phase, the agent's survival/persistence in blood during processing/storage, and lastly that the agent must be recognized as responsible for a clinically apparent outcome in at least a proportion of recipients who become infected. Without these attributes, agents are not considered as a transfusion-transmission threat and were excluded. Sixty-eight such agents were identified with enough evidence/likelihood of transfusion transmission (e.g., blood phase) and potential for clinical disease to warrant further consideration. In the Supplement, Fact Sheets (FS) were published providing information on: agent classification; disease agent's importance; clinical syndromes/diseases caused; transmission modes (including vectors/reservoirs); likelihood of transfusion transmission, and if proven to be transfusion-transmitted, information on known cases; the feasibility/predicted success of interventions for donor screening (questioning) and tests available for diagnostics/ adapted for donor screening; and finally, the efficacy, if known, of inactivation methods for plasma-derived products. The Supplement included a separate section on pathogen reduction using published data. Agents were prioritized relative to their scientific/epidemiologic threat and their perceived threat to the community including concerns expressed by the regulators of blood. Agents given the highest priority due to a known transfusion-transmission threat and severe/fatal disease in recipients were the vCJD prion, dengue viruses and the obligate red-cell parasite that causes babesiosis ( NEXT STEPS: Since the publication of the Supplement, six new FSs (yellow fever viruses-including vaccine breakthrough infections, miscellaneous arboviruses, XMRV, human parvoviruses/bocaviruses other than B19, and most recently the Middle East respiratory syndrome coronavirus, MERS-CoV) were added and 14 existing FSs updated (Anaplasma, Babesia, Bartonella, Erhlichia, chronic wasting disease-CWD, human prions other than vCJD, vCJD,

conclusionsThe process and final product (toolkit) including methods to monitor EID agent emergence, identification/recognition of a transfusion-transmission threat, methods for quantitative risk assessments, and the appropriate management of such threats should be considered for implementation by all blood systems.