Xenozoonoses and the xenotransplant recipient

The use of animal cells, tissues, or organs for humans is being investigated as an alternative to allotransplantation and as therapy for a broad range of disease states including diabetes, Parkinson's disease, and neurologic pain control. The risk of transmitting novel infections with these tissues, xenozoonoses, has led to much debate. It is well recognized that infections are a hazard with the use of all biologic agents. In addition, infections from human donors remain a major cause of morbidity and mortality after allotransplantation. Accordingly the potential for animal microbial agents to be pathogenic in the human recipient after xenotransplantation and be transmissible to others must be critically examined. Along with laboratory-based research, clinical trials must be conducted in a manner to evaluate the transmission of potential animal infections. Pretransplant evaluation should include discussions with the candidate and, if possible, with close contacts. Information must be provided as to the potential risks of infection and transmission to others. Behavioral modifications which can decrease spread of infections should be emphasized. Serial samples should be obtained from the patients at defined intervals and if recipients become ill. In addition, archiving samples for future evaluation is critical. Prospective evaluation will enhance the ability to define and understand the spectrum of xenogeneic infections.