Non-CMV Viral Infections Following Solid-Organ Transplantation – Focus on Human T-Cell Lymphotropic Virus Type-1 and Human Herpesviruses-6,-7 and-8

In non-endemic regions of the world, human T-cell lymphotropic virus type-1 (HTLV-1) is an uncommon pathogen in the transplant host, but can be associated with significant morbidity and mortality. Careful assessment for risk factors, targeted screening and heightened awareness of the clinical presentation of HTLV-1 associated disease is necessary for timely recognition and management in the transplant host. The use of antiretroviral agents in the management of symptomatic disease due to HTLV-1 remains controversial. Human herpesvirus-6 (HHV-6) has long been recognized as a pathogen in the transplant host however, establishing pathogenicity remains a challenge in clinical situations. Chromosomally integrated HHV-6 has been reported in ~1% of the solid-organ and allogeneic stem cell transplant population; and is often mistaken for active infection. Increased recognition of this entity is needed to avoid unnecessary use of antiviral medications. Current guidelines recommend against screening and treatment of asymptomatic HHV-6 infection in the solid-organ transplant host. Human herpesvirus-7 (HHV-7) is often diagnosed as co-infection with other beta-herpesviruses, but pathogenicity is less clear. There continues to be no clinical syndrome solely attributable to HHV-7. Human herpesvirus-8 (HHV-8) infection following organ transplantation can be due to primary acquisition from donor or non-donor derived exposures; or secondary to reactivation of latent infection in a seropositive recipient. Kaposi sarcoma is the most common HHV-8 associated post-transplant complication however, there is increasing recognition of non-neoplastic syndromes of febrile illness with bone marrow suppression and hemophagocytic syndrome. Lack of standardized laboratory assays for HHV-8 remains an impediment to targeted screening of high risk organ donors and recipients. A multi-disciplinary approach is needed for management of HHV-8 associated diseases.