Overt and occult hepatitis B among immigrants and native blood donors in Madrid, Spain

The risk of transfusion-transmitted viral infections is very low in developed countries. Recent massive migration flows from highly hepatitis B virus (HBV), hepatitis C virus (HCV) and/or HIV endemic regions to Europe may have changed this scenario.

During 2017 and 2018, a total of 491,753 blood donations (291,762 donors) were evaluated at the Madrid Regional Transfusion Center. All were tested for hepatitis B surface antigen (HBsAg), anti-HCV and anti-HIV, as well as for HBV-DNA, HCV-RNA and HIV-RNA.

Overall, 35 donors were positive for HIV-RNA and 26 for HCV-RNA. HBV markers were found in 111 (0.022%) donors, split out into three categories: HBsAg+ (n = 93; 0.019%), occult B infection (OBI) (n = 17; 0.003%), and acute HBV window period (n = 1; 0.0002%). All 17 OBI donors were positive for anti-HBc and confirmed as viremic in repeated testing. Viral load amounts were uniformly below 100 IU/mL. Ten OBI donors were repeated donors and look-back studies could be completed for eight of them. Fortunately, none of all prior recipients experienced transfusion transmitted hepatitis B. Compared with HBsAg+ donors, OBI donors were more frequently native Spaniards (76% versus 40%) and older (median age 52 versus 42 years old).

Active HBV infection is currently found in 0.022% of blood donations (0.038% of donors) in Madrid. This rate is 3-fold greater than for HIV and/or HCV. On the other hand, HBsAg+ donors are 3-fold more frequent than OBI donors and more often immigrants than native Spaniards. No transfusion-transmitted HBV infections were identified during the study period, including retrospective checking of former recipients of OBI donors.