BK virus in solid organ transplant recipients: An emerging syndrome

BK virus is a human polyomavirus associated with a range of clinical presen tations from asymptomatic viruria with pyuria to ureteral ulceration with u reteral stenosis in renal transplant patients or hemorrhagic cystitis in bo ne marrow transplant recipients. Infection of renal allografts has been ass ociated with diminished graft function in some individuals. Fortunately, ho wever, the majority of patients with BK virus infections are asymptomatic. The type, duration, and intensity of immunosuppression are major contributo rs to susceptibility to the activation of BK virus infection. Histopatholog y is required for the demonstration of renal parenchymal involvement; urine cytology and viral polymerase chain reaction methods are useful adjunctive diagnostic tools. Current, treatment of immunosuppressed patients with pol yomavirus viruria is largely supportive and directed toward minimizing immu nosuppression. Improved diagnostic tools and antiviral therapies are needed for polyomavirus infections.