L¿INFEZIONE DA WEST NILE VIRUS IN LOMBARDIA: STUDIO DI INCIDENZA E DI PREVALENZA NEI DONATORI DI SANGUE

In August 2008, the infection of WNV (West Nile Virus) was reported in animals and humans for the first time in Italy. WNV can potentially be transmitted with blood and blood components transfusion. We have performed a study of incidence of WNV in the area of Mantova (considered at high risk) and a study of prevalence of anti-WNV in Lombardia in blood donors. For the first study, in August-October 2009 and July-November 2010 periods, all donors consecutively admitted to the DMTE (Department of Transfusion Medicine and Haematology) of Mantova were screened for WNV RNA by NAT test. In the same periods, for the second study around 15000 plasma samples of donors per year were collected in the 15 DMTE in Lombardia and tested for antibodies anti-WNV IgG by test EIA. Samples repeatedly positive for anti-WNV IgG were tested for anti-WNV IgM (EIA and IFA), anti-WNV IgG avidity and WNV RNA. In the incidence study, in 2009 one (0.012%) of the 8193 plasma samples screened was found positive for WNV RNA; in 2010 no one of 11371 plasma samples was found positive. Regarding the prevalence study, 104 (0.67%) of 15209 plasma samples resulted positive for anti-WNV IgG; 10 (0.06%) samples were positive also for anti-WNV IgM. In 2010, 123 (0.79%) of 15542 plasma samples were positive for anti-WNV IgG; 4 samples (0.02%) were positive also for anti-WNV IgM. All positive samples were tested for WNV RNA by PCR: none of them resulted positive. The data obtained from this study show the presence of WNV in Lombardia, with some geographical differences.