VIRAL INFECTIONS TRANSMITTED THROUGH TISSUE TRANSPLANTATION

The incidence of tissue allograft-transmitted infection is unknown and can best be inferred from prospective studies – that have not yet been performed and reported. Viral infections have been transmitted via tissue allografts such as bone, skin, cornea, and heart valves. Bone allografts have transmitted hepatitis C, human immunodeficiency virus (HIV-1), and human T-cell leukaemia virus. Corneas have transmitted rabies, hepatitis B virus, cytomegalovirus (CMV), and herpes simplex virus. Heart valves have been implicated in transmitting hepatitis B. HIV-1 and CMV have been transmitted by skin allografts. Use of comprehensive donor eligibility criteria; excluding potential donors with behaviours risky for HIV-1 and hepatitis infection, and donor blood testing have greatly reduced the risk. Recent reports of HIV transmitted from a seronegative donors prompts the addition of viral nucleic acid testing of the donor. During tissue processing, many allografts are exposed to disinfectants and sterilisation steps such as gamma irradiation, which further reduce or remove the risk of transmitted disease. Some viruses are fairly resistant to gamma irradiation and the high doses needed may be harmful to the tissue allografts. Because the effectiveness of some tissue grafts depends on cellular viability, not all can be subjected to sterilisation steps, and, therefore, the risk of infectious disease transmission remains. For these, preventing the transmission of viral infection relies mostly on careful donor selection and viral testing, but processing with mild disinfectant can be useful. To further assure safety in the use of allografts, the physician and hospital should select tissue banks that follow national professional standards as their source for allografts.