Human herpes virus 8 (HHV8) or Kaposi's sarcoma associated herpes virus (KSHV) is a member of the gamma-herpes virus subfamily. HHV8 is distributed worldwide with five distinct subtypes (A to E). Seroprevalence of HHV8 varies widely, being highest in Africa and Mediterranean regions and relatively low in western countries. HHV8 is regarded as the causative agent of Kaposi's sarcoma and it is also found in a small group of lymphoproliferative disorders namely primary effusion lymphoma, (PEL) multicentric Castleman's disease (MCD) and MCD- associated plasmablastic lymphoma.
Infection with HHV8 is generally without consequence in immunocompetent hosts. In patients who are immunodeficient either through infection (HIV) or transplant associated immunosuppression, HHV8 may reactivate and cause lymhoproliferative disease. Kaposi's sarcoma (KS) occurs in 0.5 %- 5% of organ transplant recipients, depending on the patient's geographic origin and the immunosuppressive regimen used .
Assessment of HHV8 viral load in WBC and plasma provides a useful tool for detection of HHV8 reactivation and therefore risk of HHV8 disease and for monitoring response to intervention.