Assessing dengue outbreak risks to blood donation safety, beyond significant outbreak areas in Australia

Dengue can cause mild or no symptoms, meaning infected individuals can donate blood during the viraemic phase. Although transfusion transmission is rare, globally many blood operators restrict or test donors returning from dengue transmission areas before donating in non-endemic regions. While Australia does not have endemic dengue, it has receptive areas with established competent mosquitoes, and local transmission has occurred. We assessed the residual risk to transfusion safety posed by travellers from outbreak-affected receptive areas to other areas of Australia to inform evidence-based blood safety policies.

Dengue outbreaks were identified using National Notifiable Disease Surveillance System data, spatial classification, outbreak thresholds and literature-based parameters. We used the European Up-Front Risk Assessment Tool alongside national surveillance and population data to model transfusion risk at national and sub-national levels during significant local outbreak periods in Australia.

The estimated risk of severe outcomes from dengue-infected blood components was extremely low-between 1 in 13.4 billion and 1 in 1.34 trillion at the national level. The risk differed regionally but still had only a negligible absolute impact.

The residual risk of transfusion-transmitted dengue from travellers returning from outbreaks in Australia to non-receptive regions is extremely low. These findings support that additional travel questions, restrictions or testing are unnecessary beyond the outbreak areas. This study provides a robust, evidence-based framework for geographically targeted, risk-based policies and concludes that additional restrictions outside the outbreak areas are not required to maintain negligible blood safety risk in Australia.