Emerging viral infections in transplant recipients

Transplant patients are uniquely predisposed to emerging infections for a number of reasons. Two outbreaks, West Nile virus and severe acute respiratory syndrome, have recently provided important lessons on how transplant patients are affected, and how transplant programmes must adapt and evolve in the face of emerging infections. An update of emerging infections in transplant patients, using West Nile virus and severe acute respiratory syndrome as specific examples, is summarized here.

Exogenous immunosuppression, specific allograft factors, and extensive contact with the healthcare system all predispose transplant patients to emerging infections. Transplant patients may acquire West Nile virus through blood transfusion, donor transmission, or community exposure. Seroprevalence data in transplant populations suggest the risk of severe neurological disease is several fold higher in transplant recipients who acquire West Nile virus compared with immunocompetent individuals. Prevention strategies are critical in this population. These include nucleic acid testing of blood products and potentially also screening organ donors in a similar manner. During the outbreak of severe acute respiratory syndrome, transplant patients with severe and rapidly progressive disease were reported. Higher viral burdens appeared to be present in transplant patients and may have implications for the increased infectivity of these patients. Transplant programmes in severe acute respiratory syndrome areas were also adversely affected because of donor concerns, recipient issues and resource problems.

Transplant patients are uniquely predisposed to emerging infections. Lessons learned from West Nile virus and severe acute respiratory syndrome in transplantation should be applicable to future outbreaks of other emerging infectious diseases.