Assessing infectious threats – trick or threat?

Abstract

BackgroundEffective surveillance for, and response to, emerging infectious disease (EID) agents is a pivotal component of blood safety risk management policy. The rate of emergence of new potential agents is increasing which demands a robust risk management strategy for rapidly assessing and ranking potential threats. This review discusses the general principles of threat assessment for EID agents.MethodsVarious schema for the management of the risk posed by EID agents have been proposed. Examples are the AABB ‘toolkit’ for EIDs which includes a framework for recognition, assessment and management of EID agents, and the Australian Red Cross Blood Service's EID management strategy. Both systems incorporate EID agent ‘templates’ to assist with ranking the threat level and formulating an appropriate response.ResultsThreats are primarily assessed based on three main criteria: prevalence in donor population, transmissibility by blood and the severity of clinical disease in recipients. Where the threat is deemed significant, quantitative risk assessment and cost‐effectiveness analysis for potential interventions can assist in defining the most appropriate mitigation strategy. Hepatitis E virus (HEV) is an excellent contemporary case study with transfusion–transmissibility now proven, but further studies required to define the extent of clinically significant disease in immunocompetent recipients.ConclusionsThe emergence of vCJD and subsequently West Nile virus underscored the importance of an effective EID risk management framework. However, not all EIDs necessarily pose a significant threat to blood safety, and therefore, an effective ranking system is required which we suggest should primarily assess prevalence, transmissibility and recipient disease outcome.