[The expansion of vector-borne diseases and the implications for blood transfusion safety: The case of West Nile Virus, dengue and chikungunya].

Arbovirus infections are increasing in prevalence worldwide. This presents new risks for blood transfusion. This article describes the epidemiology and surveillance of West Nile Virus, dengue and chikungunya and their role in the risk management of transfusions. Arboviruses are RNA viruses and very adaptable by nature. The majority of arbovirus infections are zoonoses. The risk of transmission is multifactorial and concerns the virus, vectors, animal reservoirs, the environment and human behaviour. In recent years, West Nile Virus has become established and widespread in North America, the number of cases of dengue worldwide has increased dramatically, and major epidemics of chikungunya have occurred in the Indian Ocean and Asia. The transmission of dengue and chikungunya is demonstrated in temperate zones. All arboviruses are potentially transmissible by transfusion due to their capacity to induce an asymptomatic viremic phase. The risk of West Nile Virus transmission via transfusion is recognised and prevention measures are well established. The risk of transmission via transfusion of dengue and chikungunya is real but difficult to quantify and the optimum prevention strategy is currently the subject of research. Access to up-to-date epidemiological data is an essential aid to decision-making, especially for donors returning from endemic areas to Europe. The challenge is to define and implement appropriate measures in unpredictable situations.