Juhl David, Hennig Holger
Institute of Transfusion Medicine, University Hospital of Schleswig-Holstein, Lübeck, Germany.
Front Med (Lausanne). 2018 Feb 1;5:4. doi: 10.3389/fmed.2018.00004. eCollection 2018.
Parvovirus B19 (B19V) has been discovered in 1975. The association with a disease was unclear in the first time after the discovery of B19V, but meanwhile, the usually droplet transmitted B19V is known as the infectious agent of the "fifth disease," a rather harmless children's illness. But B19V infects erythrocyte progenitor cells and thus, acute B19V infection in patients with a high erythrocyte turnover may lead to a life-threatening aplastic crisis, and acutely infected pregnant women can transmit B19V to their unborn child, resulting in a hydrops fetalis and fetal death. However, in many adults, B19V infection goes unnoticed and thus many blood donors donate blood despite the infection. The B19V infection does not impair the blood cell counts in healthy blood donors, but after the acute infection with extremely high DNA concentrations exceeding 10 IU B19V DNA/ml plasma is resolved, B19V DNA persists in the plasma of blood donors at low levels for several years. That way, many consecutive donations that contain B19V DNA can be taken from a single donor, but the majority of blood products from donors with detectable B19V DNA seem not to be infectious for the recipients from several reasons: first, many recipients had undergone a B19V infection in the past and have formed protective antibodies. Second, B19V DNA concentration in the blood product is often too low to infect the recipient. Third, after the acute infection, the presence of B19V DNA in the donor is accompanied by presumably neutralizing antibodies which are protective also for the recipient of his blood products. Thus, transfusion-transmitted (TT-) B19V infections are very rarely reported. Moreover, in most blood donors, B19V DNA concentration is below 1,000 IU/ml plasma, and no TT-B19V infections have been found by such low-viremic donations. Cutoff for an assay for B19V DNA blood donor screening should, therefore, be approximately 1,000 IU/ml plasma, if a general screening of blood donors for single donation blood components is considered at all: for the overwhelming majority of transfusion recipients, B19V infection is not relevant as well as for the blood donors. B19V DNA screening of vulnerable patients after transfusion seems to be a more reasonable approach than general blood donor screening.
细小病毒B19（B19V）于1975年被发现。在B19V被发现后的最初阶段，其与疾病的关联尚不清楚，但与此同时，通常通过飞沫传播的B19V被认为是“第五病”的病原体，这是一种对儿童危害较小的疾病。然而，B19V会感染红细胞祖细胞，因此，红细胞更新率高的患者发生急性B19V感染可能会导致危及生命的再生障碍危象，而急性感染的孕妇可将B19V传播给未出生的胎儿，导致胎儿水肿和死亡。然而，在许多成年人中，B19V感染未被察觉，因此许多献血者在感染后仍献血。B19V感染不会影响健康献血者的血细胞计数，但在急性感染后，当极高的DNA浓度（超过10 IU B19V DNA/ml血浆）消失后，B19V DNA会在献血者血浆中持续低水平存在数年。这样，同一个献血者可能会有多次含有B19V DNA的连续献血，但由于多种原因，来自检测到B19V DNA的献血者的大多数血液制品似乎对受血者没有传染性：首先，许多受血者过去曾感染过B19V并已形成保护性抗体。其次，血液制品中的B19V DNA浓度通常过低，无法感染受血者。第三，急性感染后，献血者体内B19V DNA的存在伴随着可能具有中和作用的抗体，这些抗体对其血液制品的受血者也有保护作用。因此，输血传播（TT-）B19V感染的报道非常罕见。此外，在大多数献血者中，B19V DNA浓度低于1000 IU/ml血浆，通过这种低病毒血症的献血未发现TT-B19V感染。因此，如果考虑对单一献血成分进行献血者普遍筛查，那么B19V DNA献血者筛查检测的临界值应约为1000 IU/ml血浆：对于绝大多数输血受血者和献血者来说，B19V感染都无关紧要。对输血后易感患者进行B19V DNA筛查似乎比普遍的献血者筛查更为合理。
