CD52 and graft versus host disease: There are several well-known risk factors for severe adenovirus infections, including: allogeneic stem cell (or solid-organ) transplantation, particularly with T-cell depletion; treatment with anti-CD52 monoclonal antibody (alemtuzumab or Campath) or anti-thymocyte globulin (ATG); severe immunosuppression used to treat graft-versus-host disease; and any other cause of severe lymphopaenia that reduces the ability of the host’s cell-mediated immunity to defend against adenovirus infection [1].