1. Most viral infections after SCT are caused by the endogenous reactivation of persistent pathogens such as adenovirus (ADV), cytomegalovirus (CMV), and Epstein-Barr-virus (EBV), whereas invasive infections due to Aspergillus spp. are mostly exogenous.

Adeno-, Zytomegalie- und Epstein-Barr-Viren reaktivieren meist endogen, während Aspergillusinfektionen v. a. exogen entstehen.