USUV in Europe is detected in vectors (mosquitoes) and has a reservoir in vertebrates. There are known fatal epidemics among birds, especially blackbirds. Currently, USUV also causes rare infections in humans. However, the emergence of clinical cases, including severe neurological symptoms, and the finding of seroprevalence in asymptomatic people (e.g. blood donors, forest workers), indicate that USUV, due to its neurotropism, may become a potential public health problem. Therefore, it is very important to monitor cases infections in humans, migratory and resident birds and other animals that may constitute a reservoir of the virus, but also detection of the virus in mosquitoes (vectors), including alien and invasive species, as well as the impact of climatic factors on the ability to spread the virus in the Europe. There is currently no evidence of virus transmission during transfusion or transplantation, but the potential risk of virus transmission from an asymptomatic blood donor to an mmunocompromised recipient must be considered. Although the occurrence of USUV in European countries is currently not a significant threat, surveillance and screening of blood donors for USUV should be carried out during the period of vector activity and during WNV epidemics, as well as in patients with symptoms of meningitis and encephalitis.