The Usutu virus reaches Mallorca: first confirmed case in Spain

PalmThe Balearic Islands Blood Bank (BSTIB) has participated in a study confirming the detection of the first case of Usutu virus infection in Spain, in a donor from Mallorca. The case was identified in June 2024 in a donor residing in Mallorca. The sample tested reactive in routine tests for West Nile virus. After being sent to the national reference laboratory for arboviruses at the Carlos III Health Institute, specific tests confirmed that it was an infection with the Usutu virus, an emerging arbovirus in Europe transmitted by mosquitoes of the Culex genus. In addition to the Mallorca case, the study detected two additional infections in Catalonia, confirmed using molecular biology techniques and genomic sequencing. All three cases appeared in donors who had not traveled outside their autonomous community, demonstrating local circulation of the virus. The work was published in Transfusion It has been developed by a multidisciplinary team that includes the Balearic Islands Blood Bank, the Blood and Tissue Bank of Catalonia, the Institute of Agrifood Research and Technology (CReSA), the National Center for Microbiology of the Carlos III Health Institute, and the Bernhard Nocht Institute for Tropical Medicine in Germany. The authors have highlighted that the techniques commonly used for West Nile virus screening also allow for the detection of Usutu infections, thanks to the cross-reactivity between the two viruses. This facilitates the early identification of infected donors and strengthens transfusion safety. The Usutu virus was first detected in Africa in 1959, and in recent years it has shown progressive expansion into several European countries. Most infections are asymptomatic, but they can affect immunocompromised individuals.