A new scientific review by the European Centre for Disease Prevention and Control (https://www.ecdc.europa.eu/en/publications-data/transmission-selected-arboviruses-through-substances-human-origin-soho-scoping) has identified a total of 77 cases of possible or confirmed transmission of arboviruses through blood, hematopoietic cells or breastfeeding in Europe.
Arboviruses are usually transmitted by mosquitoes or ticks. The ECDC report confirms, however, that some can rarely pass from one person to another through substances of human origin.
Of the 77 recorded cases, 71 involved transfusions of blood or blood derivatives. Three were linked to haematopoietic stem cell transplantation and another three to possible transmission through breastfeeding.
The review covered scientific publications from January 2000 to June 2025. These are recorded cases in the international literature and not an estimate of the overall frequency of the phenomenon.
West Nile virus in first place
Most transmissions, a total of 47, were linked to the West Nile virus. Of these, 45 were performed through platelets, red blood cells, plasma or granulocytes.
Dengue fever was associated with 26 cases, of which 23 were transfusions. Four cases of Zika were recorded, with three related to platelets.
A common feature of several cases was that the donors had no symptoms when they donated blood or were at a very early stage of the infection. In some cases, the concentration of the virus was lower than the detection limit of the tests used.
The most severe effects occurred mainly in immunocompromised patients and children, i.e. recipients who were already more vulnerable to infections.
The cases of Greece
Among the European records are four confirmed blood transmissions of West Nile virus in Greece, which were detected from data from the period 2010-2021.
Two cases involved patients with thalassemia who received infected red blood cells and developed severe disease. In another case, the blood donation had taken place a week before the preventive measures to protect the blood supply were put in place.
The Greek incidents highlight the importance of quickly informing blood donation services when the virus is detected in a specific area.
Cyprus is "clean", but surveillance is required
The review does not record an incident of arbovirus transmission through blood or haematopoietic cells in Cyprus. However, this does not constitute proof of zero future risk, nor does it mean that surveillance can be limited.
The Aedes aegypti mosquito is established in the country, which can transmit dengue fever, Chikungunya and Zika. Aedes albopictus, known as the tiger mosquito, is also present.
The presence of these mosquitoes does not mean that viruses are circulating in Cyprus. It does, however, create the conditions for local transmission if a virus is introduced, for example via an infected traveller, and the right conditions prevail.
The ECDC emphasizes risk-appropriate surveillance, sensitive molecular testing, donor monitoring, and prompt action during outbreaks. The report does not argue that universal testing of every blood donation is required for all arboviruses.
For Chikungunya, Usutu and Crimean-Congo haemorrhagic fever, no cases of transmission through substances of human origin were identified. Scientists clarify that this may reflect a really low risk, but also incomplete recognition or investigation of incidents.
