In central Europe, West-Nile-Virus (WNV) infections are endemic in small regions and only seasonal small outbreaks occur outside these regions. Therefore, WNV infection risk for blood donors is difficult to assess. One can test all donors by WNV PCR, but that is extremely costly and far more than 99% will be tested negative. However, in the U.S. with their high prevalence of WNV, the WNV PCR has proven cost effective. Alternatively, European blood transfusion centers defer blood donors travelling through "WNV regions" for 4 weeks. What is the strategy, you and your Institution prefers?